Environmental Science › Nature and Landscape Conservation

Fish Ecology and Management Studies

Works Count: 165058

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Description

This cluster of papers focuses on the importance, threats, status, and conservation challenges related to freshwater biodiversity. It covers topics such as flow regulation, hydropower dam construction, environmental flows, invasive species, climate change impacts, fisheries sustainability, and habitat fragmentation in river ecosystems.

Keywords

Freshwater Biodiversity; Conservation Challenges; Flow Regulation; Hydropower Dam Construction; Environmental Flows; Invasive Species; Climate Change; Fisheries Sustainability; Habitat Fragmentation; River Ecosystems

Physiology and Climate Change

2008-10-30

Hans‐Otto Pörtner , Anthony P. Farrell

Endurance Swimming Is Related to Summer Lake Survival of Rainbow Trout in a Warm Lake with Avian Piscivores, Endurance Swimming Is Related to Summer Lake Survival of Rainbow Trout in a Warm Lake with Avian Piscivores,

Growth Rates and Models

1979-01-01

W. E. Ricker

Predation: Direct and Indirect Impacts on Aquatic Communities

1988-05-18

Larry B. Crowder , W. Charles Kerfoot , Andrew Sih

Landscapes to Riverscapes: Bridging the Gap between Research and Conservation of Stream Fishes

2002-01-01

Kurt D. Fausch , Christian E. Torgersen , Colden V. Baxter +1 more

The Role of Disturbance in Stream Ecology

1988-12-01

Vincent H. Resh , Arthur V. Brown , Alan P. Covich +7 more

We define disturbance in stream ecosystems to be: any relatively discrete event in time that is characterized by a frequency, intensity, and severity outside a predictable range, and that disrupts … We define disturbance in stream ecosystems to be: any relatively discrete event in time that is characterized by a frequency, intensity, and severity outside a predictable range, and that disrupts ecosystem, community, or population structure and changes resources or the physical environment. Of the three major hypotheses relating disturbance to lotic community structure, the dynamic equilibrium hypothesis appears to be generally applicable, although specific studies support the intermediate disturbance hypothesis and the equilibrium model. Differences in disturbance frequency between lentic and lotic systems may explain why biotic interactions are more apparent in lakes than in streams. Responses to both natural and anthropogenic disturbances vary regionally, as illustrated by examples from the mid-continent, Pacific northwest, and southeastern United States. Based on a generalized framework of climatic-biogeochemical characteristics, two features are considered to be most significant in choosing streams for comparative studies of disturbance: hydrologic regimes and comparable geomorphology. A method is described for quantifying predictability of the hydrologic regime based on long-term records of monthly maximum and minimum stream flows. Different channel forms (boulder and cobble, alluvial gravelbed, alluvial sandbed) have different responses to hydrologic disturbance from spates. A number of structural and functional components for comparing disturbance effects within regions and across biomes are presented. Experimental approaches to studying disturbance involve spatial-scale considerations, logistic difficulties, and ethical questions. General questions related to disturbance that could be addressed by stream ecologists are proposed.

Primary Production in Flowing Waters1

1956-04-01

Howard T. Odum

Respiration, photosynthetic production, and diffusion interact to produce the daily curve of oxygen change in a segment of flowing water. Conversely, the observed curves of oxygen in streams can be … Respiration, photosynthetic production, and diffusion interact to produce the daily curve of oxygen change in a segment of flowing water. Conversely, the observed curves of oxygen in streams can be used to calculate the component rates of production, respiration, and diffusion. New production values obtained with these analyses of oxygen curves from various sources, as well as a few previously existing estimates of primary production, indicate a generally higher rate of production in flowing waters than in other types of aquatic environments. The ratio of total primary production to total community respiration is used to classify communities quantitatively according to their predominantly heterotrophic or autotrophic characteristics. Longitudinal succession within a stream tends to modify the ratio towards unity from higher values for autotrophic and from lower values for heterotrophic communities. The behavior of this ratio is described for the annual cycle in a stream, for the sequence of pollution recovery, and for diverse types of communities.

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Basic Principles and Ecological Consequences of Altered Flow Regimes for Aquatic Biodiversity

2002-10-01

Stuart E. Bunn , Angela H. Arthington

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A global perspective on environmental flow assessment: emerging trends in the development and application of environmental flow methodologies for rivers

2003-09-01

Rebecca E. Tharme

Abstract Recognition of the escalating hydrological alteration of rivers on a global scale and resultant environmental degradation, has led to the establishment of the science of environmental flow assessment whereby … Abstract Recognition of the escalating hydrological alteration of rivers on a global scale and resultant environmental degradation, has led to the establishment of the science of environmental flow assessment whereby the quantity and quality of water required for ecosystem conservation and resource protection are determined. A global review of the present status of environmental flow methodologies revealed the existence of some 207 individual methodologies, recorded for 44 countries within six world regions. These could be differentiated into hydrological, hydraulic rating, habitat simulation and holistic methodologies, with a further two categories representing combination‐type and other approaches. Although historically, the United States has been at the forefront of the development and application of methodologies for prescribing environmental flows, using 37% of the global pool of techniques, parallel initiatives in other parts of the world have increasingly provided the impetus for significant advances in the field. Application of methodologies is typically at two or more levels. (1) Reconnaissance‐level initiatives relying on hydrological methodologies are the largest group (30% of the global total), applied in all world regions. Commonly, a modified Tennant method or arbitrary low flow indices is adopted, but efforts to enhance the ecological relevance and transferability of techniques across different regions and river types are underway. (2) At more comprehensive scales of assessment, two avenues of application of methodologies exist. In developed countries of the northern hemisphere, particularly, the instream flow incremental methodology (IFIM) or other similarly structured approaches are used. As a group, these methodologies are the second most widely applied worldwide, with emphasis on complex, hydrodynamic habitat modelling. The establishment of holistic methodologies as 8% of the global total within a decade, marks an alternative route by which environmental flow assessment has advanced. Such methodologies, several of which are scenario‐based, address the flow requirements of the entire riverine ecosystem, based on explicit links between changes in flow regime and the consequences for the biophysical environment. Recent advancements include the consideration of ecosystem‐dependent livelihoods and a benchmarking process suitable for evaluating alternative water resource developments at basin scale, in relatively poorly known systems. Although centred in Australia and South Africa, holistic methodologies have stimulated considerable interest elsewhere. They may be especially appropriate in developing world regions, where environmental flow research is in its infancy and water allocations for ecosystems must, for the time being at least, be based on scant data, best professional judgement and risk assessment. Copyright © 2003 John Wiley & Sons, Ltd.

The Population Consequences of Life History Phenomena

1954-06-01

LaMont C. Cole

Ecology: From Individuals to Ecosystems

2006-07-28

Rob Briers

Methods in Stream Ecology.

1997-04-01

Mark S. Wipfli , F. Richard Hauer , Gary A. Lamberti

Methods in Stream Ecology provides a complete series of field and laboratory protocols in stream ecology that are ideal for teaching or conducting research. This new edition is updated to … Methods in Stream Ecology provides a complete series of field and laboratory protocols in stream ecology that are ideal for teaching or conducting research. This new edition is updated to reflect recent advances in the technology associated with ecological assessment of streams, including remote sensing. In addition, the relationship between stream flow and alluviation has been added, and a new chapter on riparian zones is also included.With a student-friendly price, this Second Edition is a key for all students and researchers in stream and freshwater ecology, freshwater biology, marine ecology, and river ecology. This text is also supportive as a supplementary text for courses in watershed ecology/science, hydrology, fluvial geomorphology, and landscape ecology. It includes: exercises in each chapter; detailed instructions, illustrations, formulae, and data sheets for in-field research for students; taxanomic keys to common stream invertebrates and algae; website with tables; and, link from chapter 22: Fish Community Composition to an interactive program for assessing and modeling fish numbers.

The Respiratory Metabolism and Swimming Performance of Young Sockeye Salmon

1964-05-01

J. R. Brett

The rate of oxygen consumption in young sockeye salmon (Oncorhynchus nerka) was determined for various swimming speeds, including fatigue levels, at temperatures of 5, 10, 15, 20, and 24 °C. … The rate of oxygen consumption in young sockeye salmon (Oncorhynchus nerka) was determined for various swimming speeds, including fatigue levels, at temperatures of 5, 10, 15, 20, and 24 °C. A logarithmic increase in oxygen demand with increase in swimming speed characterized each acclimation temperature. Extrapolation to zero activity (standard metabolism) and maximum activity (active metabolism) provided differences of the order of 10 to 12 times the minimum rate.The greatest scope for activity occurred at 15 °C with an average active metabolic rate of 895 mg O 2 /kg/hr for a swimming speed of 4.1 body lengths per second, just maintained for 1 hr. Above 15 °C active metabolism was limited, apparently by oxygen availability.Rate of replacement of oxygen debt following fatigue was determined by tracing the return to a resting state of metabolism, and confirmed by re-tests at fatigue velocities. In most instances the rate declined logarithmically with time; in some there was an initial or secondary slump. Times to recovery (return of spontaneous activity) averaged 3.2 hr, independent of acclimation temperature.Swimming speed–fatigue tests indicated a sustained level of performance at about 200–300 min. Comparison with other fish suggests a marked change in slope of the fatigue curve at about 20 sec. The effect of temperature was greatest on sustained speeds and least on burst speeds.

Predation, Body Size, and Composition of Plankton

1965-10-01

John Langdon Brooks , Stanley I. Dodson

Landscape Filters and Species Traits: Towards Mechanistic Understanding and Prediction in Stream Ecology

1997-06-01

N. LeRoy Poff

A heuristic framework for understanding and predicting the distribution and categorical abundance of species in stream communities is presented. The framework requires that species be described in terms of their … A heuristic framework for understanding and predicting the distribution and categorical abundance of species in stream communities is presented. The framework requires that species be described in terms of their functional relationships to habitat selective forces or their surrogates, which constitute "filters" occurring at hierarchical landscape scales (ranging from microhabitats to watersheds or basins). Large-scale filters are viewed as causative or mechanistic agents that constrain expression of local selective forces or biotic potential at lower scales. To join a local community, species in a regional pool must possess appropriate functional attributes (species traits) to "pass" through the nested filters. Biotic interactions are also a potential filter on local community composition, and they are invoked at the lower hierarchical levels, after species have passed through the physicochemical habitat filters. Potential landscape filters and their associated selective properties are identified, as are prospective species traits (for invertebrates and fish) that correspond with filters. A categorical niche model is used to illustrate how relative abundances of species in local communities might be predicted from habitat data collected at different scales. The framework emphasizes a biologically based approach to understanding and predicting species distribution and abundance and local community composition by explicitly considering environmental constraints imposed at different scales. As such, it can complement non-mechanistic, correlative approaches to community prediction that often lack generality. Operationalizing the framework will require additional research to specify more clearly 1) the degree to which habitat features at different scales are linked functionally or statistically, 2) what species traits are possessed by strongly interactive species (e.g., keystones) and which habitat filters most strongly constrain the distribution of these species, and 3) the functional significance of a range of species traits and the extent to which these traits are correlated and hence respond in concert to the presence, or modification, of a particular filter. Multi-scale, mechanistic understanding of species-environment relations will likely contribute to better predictions about large scale problems, such as the establishment and spread of exotic species or alterations in community composition with changing land use or climate.

New tetranucleotide microsatellites for fine‐scale discrimination among endangered chinook salmon (Oncorhynchus tshawytscha)

2003-06-05

Carolyn Greig , David P. Jacobson , Michael A. Banks

Abstract The unambiguous identification of Central Valley spring‐run chinook salmon has become imperative since their proposed listing in 1998. The accuracy of methods used to assign individuals to their stock … Abstract The unambiguous identification of Central Valley spring‐run chinook salmon has become imperative since their proposed listing in 1998. The accuracy of methods used to assign individuals to their stock of origin is critical for understanding juvenile migration patterns and determining the success of protection measures. Existing microsatellites discriminate between the endangered winter‐run and other chinook but are insufficient to characterize phylogenetically less distinct runs. Here, we isolated and developed highly variable tetranucleotide microsatellites for the specific goal of increasing discriminatory power among closely related populations, providing a new power towards the reliable differentiation of nonwinter runs

The micronucleus test

1975-02-01

Werner Schmid

Fresh-water invertebrates of the United States

1954-01-01

Robert W. Pennak

Freshwater biodiversity conservation: recent progress and future challenges

2010-03-01

David L. Strayer , David Dudgeon

Freshwater habitats occupy <1% of the Earth's surface, yet are hotspots that support ∼10% of all known species, and ∼⅓ of vertebrate species. Fresh waters also are hotspots for human … Freshwater habitats occupy <1% of the Earth's surface, yet are hotspots that support ∼10% of all known species, and ∼⅓ of vertebrate species. Fresh waters also are hotspots for human activities that have led to widespread habitat degradation, pollution, flow regulation and water extraction, fisheries overexploitation, and alien species introductions. These impacts have caused severe declines in the range and abundance of many freshwater species, so that they are now far more imperiled than their marine or terrestrial counterparts. Here, we review progress in conservation of freshwater biodiversity, with a focus on the period since 1986, and outline key challenges for the future. Driven by rising conservation concerns, freshwater ecologists have conducted a great deal of research over the past 25 y on the status, trends, autecology, and propagation of imperiled species, threats to these species, the consequences of biodiversity loss for ecosystem functioning, metapopulation dynamics, biodiversity hotspots, reserve design, habitat restoration, communication with stakeholders, and weaknesses of protective legislation. Nevertheless, existing efforts might be insufficient to stem the ongoing and coming multitude of freshwater extinctions. We briefly discuss 4 important challenges for freshwater conservation. First, climate change will imperil both freshwater species and human uses of fresh water, driving engineering responses that will further threaten the freshwater biota. We need to anticipate both ecological and human responses to climate change, and to encourage rational and deliberate planning of engineering responses to climate change before disasters strike. Second, because freshwater extinctions are already well underway, freshwater conservationists must be prepared to act now to prevent further losses, even if our knowledge is incomplete, and engage more effectively with other stakeholders. Third, we need to bridge the gap between freshwater ecology and conservation biology. Fourth, we suggest that scientific societies and scholarly journals concerned with limnology or freshwater sciences need to improve their historically poor record in publishing important papers and influencing practice in conservation ecology. Failure to meet these challenges will lead to the extinction or impoverishment of the very subjects of our research.

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Assessment of Biotic Integrity Using Fish Communities

1981-11-01

James R. Karr

Man's activities have had profound, and usually negative, influences on freshwater fishes from the smallest streams to the largest rivers. Some negative effects are due to contaminants, while others are … Man's activities have had profound, and usually negative, influences on freshwater fishes from the smallest streams to the largest rivers. Some negative effects are due to contaminants, while others are associated with changes in watershed hydrology, habitat modifications, and alteration of energy sources upon which the aquatic biota depends. Regrettably, past efforts to evaluate effects of man's activities on fishes have attempted to use water quality as a surrogate for more comprehensive biotic assessment. A more refined biotic assessment program is required for effective protection of freshwater fish resources. An assessment system proposed here uses a series of fish community attributes related to species composition and ecological structure to evaluate the quality of an aquatic biota. In preliminary trials this system accurately reflected the status of fish communities and the environment supporting them.

Glacial history and colonization of Europe by the blue tit Parus caeruleus

2004-06-25

Laura Kvist , Keijo Viiri , Paula C. Dias +2 more

Mitochondrial control region sequences from European populations of the blue tit Parus caeruleus were used to reveal the Pleistocene history and the post‐glacial recolonization of Europe by the species. The … Mitochondrial control region sequences from European populations of the blue tit Parus caeruleus were used to reveal the Pleistocene history and the post‐glacial recolonization of Europe by the species. The southern subspecies, P. c. ogliastrae was found to represent a stable population with isolation‐by‐distance structure harboring a lot of genetic variation, and the northern subspecies P. c. caeruleus a recently bottlenecked and expanded population. We suggest that after the last Ice Ages, the subspecies have colonized Europe from two different southern refuges following previously proposed general recolonization routes from the Balkans to northern and Central Europe, and from the Iberian Peninsula north‐ and eastwards. The two subspecies form a wide secondary contact zone extending from southern Spain to southern France.

The Natural Flow Regime

1997-12-01

N. LeRoy Poff , J. David Allan , Mark B. Bain +5 more

H umans have long been fascinated by the dynamism of free-flowing waters. Yet we have expended great effort to tame rivers for transportation, water supply, flood control, agriculture, and power … H umans have long been fascinated by the dynamism of free-flowing waters. Yet we have expended great effort to tame rivers for transportation, water supply, flood control, agriculture, and power generation. It is now recognized that harnessing of streams and rivers comes at great cost: Many rivers no longer support socially valued native species or sustain healthy ecosystems that provide important goods and services (Naiman et al. 1995, NRC 1992).

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High‐resolution mapping of the world's reservoirs and dams for sustainable river‐flow management

2011-05-31

Bernhard Lehner , Catherine Reidy Liermann , Carmen Revenga +7 more

Despite the recognized importance of reservoirs and dams, global datasets describing their characteristics and geographical distribution are largely incomplete. To enable advanced assessments of the role and effects of dams … Despite the recognized importance of reservoirs and dams, global datasets describing their characteristics and geographical distribution are largely incomplete. To enable advanced assessments of the role and effects of dams within the global river network and to support strategies for mitigating ecohydrological and socioeconomic costs, we introduce here the spatially explicit and hydrologically linked Global Reservoir and Dam database (GRanD). As of early 2011, GRanD contains information regarding 6862 dams and their associated reservoirs, with a total storage capacity of 6197 km 3 . On the basis of these records, we estimate that about 16.7 million reservoirs larger than 0.01 ha – with a combined storage capacity of approximately 8070 km 3 – may exist worldwide, increasing Earth's terrestrial surface water area by more than 305 000 km 2 . We find that 575 900 river kilometers, or 7.6% of the world's rivers with average flows above 1 cubic meter per second (m 3 s −1 ), are affected by a cumulative upstream reservoir capacity that exceeds 2% of their annual flow; the impact is highest for large rivers with average flows above 1000 m 3 s −1 , of which 46.7% are affected. Finally, a sensitivity analysis suggests that smaller reservoirs have substantial impacts on the spatial extent of flow alterations despite their minor role in total reservoir capacity.

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Population diversity and the portfolio effect in an exploited species

2010-06-01

Daniel E. Schindler , Ray Hilborn , Brandon E. Chasco +4 more

Freshwater biodiversity: importance, threats, status and conservation challenges

2005-12-12

David Dudgeon , Angela H. Arthington , Mark O. Gessner +7 more

Freshwater biodiversity is the over-riding conservation priority during the International Decade for Action -'Water for Life' - 2005 to 2015. Fresh water makes up only 0.01% of the World's water … Freshwater biodiversity is the over-riding conservation priority during the International Decade for Action -'Water for Life' - 2005 to 2015. Fresh water makes up only 0.01% of the World's water and approximately 0.8 % of the Earth's surface, yet this tiny fraction of global water supports at least 100 000 species out of approximately 1.8 million - almost 6% of all described species. Inland waters and freshwater biodiversity constitute a valuable natural resource, in economic, cultural, aesthetic, scientific and educational terms. Their conservation and management are critical to the interests of all humans, nations and governments. Yet this precious heritage is in crisis. Fresh waters are experiencing declines in biodiversity far greater than those in the most affected terrestrial ecosystems, and if trends in human demands for water remain unaltered and species losses continue at current rates, the opportunity to conserve much of the remaining biodiversity in fresh water will vanish before the 'Water for Life' decade ends in 2015. Why is this so, and what is being done about it? This article explores the special features of freshwater habitats and the biodiversity they support that makes them especially vulnerable to human activities. We document threats to global freshwater biodiversity under five headings: overexploitation; water pollution; flow modification; destruction or degradation of habitat; and invasion by exotic species. Their combined and interacting influences have resulted in population declines and range reduction of freshwater biodiversity worldwide. Conservation of biodiversity is complicated by the landscape position of rivers and wetlands as 'receivers' of land-use effluents, and the problems posed by endemism and thus non-substitutability. In addition, in many parts of the world, fresh water is subject to severe competition among multiple human stakeholders. Protection of freshwater biodiversity is perhaps the ultimate conservation challenge because it is influenced by the upstream drainage network, the surrounding land, the riparian zone, and - in the case of migrating aquatic fauna - downstream reaches. Such prerequisites are hardly ever met. Immediate action is needed where opportunities exist to set aside intact lake and river ecosystems within large protected areas. For most of the global land surface, trade-offs between conservation of freshwater biodiversity and human use of ecosystem goods and services are necessary. We advocate continuing attempts to check species loss but, in many situations, urge adoption of a compromise position of management for biodiversity conservation, ecosystem functioning and resilience, and human livelihoods in order to provide a viable long-term basis for freshwater conservation. Recognition of this need will require adoption of a new paradigm for biodiversity protection and freshwater ecosystem management - one that has been appropriately termed 'reconciliation ecology'.

VASCULAR PLANT BREAKDOWN IN FRESHWATER ECOSYSTEMS

1986-11-01

Jackson R. Webster , E. F. Benfield

Species distribution models (SDMs) are numerical tools that combine observations of species occurrence or abundance with environmental estimates. They are used to gain ecological and evolutionary insights and to predict … Species distribution models (SDMs) are numerical tools that combine observations of species occurrence or abundance with environmental estimates. They are used to gain ecological and evolutionary insights and to predict distributions across landscapes, ...Read More

Landscapes and Riverscapes: The Influence of Land Use on Stream Ecosystems

2004-11-02

J. David Allan

▪ Abstract Local habitat and biological diversity of streams and rivers are strongly influenced by landform and land use within the surrounding valley at multiple scales. However, empirical associations between … ▪ Abstract Local habitat and biological diversity of streams and rivers are strongly influenced by landform and land use within the surrounding valley at multiple scales. However, empirical associations between land use and stream response only varyingly succeed in implicating pathways of influence. This is the case for a number of reasons, including (a) covariation of anthropogenic and natural gradients in the landscape; (b) the existence of multiple, scale-dependent mechanisms; (c) nonlinear responses; and (d) the difficulties of separating present-day from historical influences. Further research is needed that examines responses to land use under different management strategies and that employs response variables that have greater diagnostic value than many of the aggregated measures in current use. In every respect, the valley rules the stream. H.B.N. Hynes (1975)

Synthesizing U.S. River Restoration Efforts

2005-04-28

Emily S. Bernhardt , Margaret A. Palmer , J. David Allan +7 more

3,4085MetricsTotal Downloads3,408Last 6 Months498Last 12 Months1,067Total Citations5Last 6 Months0Last 12 Months0View all metrics 3,4085MetricsTotal Downloads3,408Last 6 Months498Last 12 Months1,067Total Citations5Last 6 Months0Last 12 Months0View all metrics

An Experimental Test of the Effects of Predation Risk on Habitat Use in Fish

1983-12-01

Earl E. Werner , James F. Gilliam , Donald J. Hall +1 more

We present an experiment designed to test the hypothesis that fish respond to both relative predation risk and habitat profitability in choosing habitats in which to feed. Identical populations of … We present an experiment designed to test the hypothesis that fish respond to both relative predation risk and habitat profitability in choosing habitats in which to feed. Identical populations of three size—classes of bluegill sunfish (Lepomis macrochirus) were stocked on both sides of a divided pond (29 m in diameter), and eight piscivorous largemouth bass (Micropterus salmoides) were introduced to one side. Sizes of both species were chosen such that the small class of bluegills was very vulnerable to the bass, whereas the largest class was invulnerable to bass predation. We then compared mortality, habitat use, and growth of each size—class in the presence and absence of the bass. Only the small size—class suffered significant mortality from the bass (each bass consumed on average about one small bluegill every 3.8 d); the two larger size—classes exhibited similar mortality rates on both sides of the pond. In the absence of the bass, we found that habitat use of all size—classes was similar and that the pattern of habitat use maximized foraging return rates (Werner et al. 1983). In the presence of the bass the two larger size—classes chose habitats to maximize return rates, but the small size—class obtained a greater fraction of its diet from the vegetation habitat, where foraging return rates were only one—third of those in the more open habitats. The small size—class further exhibited a significant depression in individual growth in the presence of the bass; the growth increment during the experiment was 27% less than that for small bluegills in the absence of the bass. Because of the reduced utilization of more open habitats by the small fish in the presence of bass, resources in these habitats were released to the larger size—classes, which showed greater growth in the presence of the bass than in its absence. We develop methods to predict the additional mortality expected on a cohort due to a reduction in growth rate (because individuals are spending a longer time in vunerable sizes), and discuss and potential for predation risk to enforce size—class segregation, which leads de facto to resource partitioning.

A working guide to boosted regression trees

2008-04-08

Jane Elith , John R. Leathwick , Trevor Hastie

1 Ecologists use statistical models for both explanation and prediction, and need techniques that are flexible enough to express typical features of their data, such as nonlinearities and interactions. 2 … 1 Ecologists use statistical models for both explanation and prediction, and need techniques that are flexible enough to express typical features of their data, such as nonlinearities and interactions. 2 This study provides a working guide to boosted regression trees (BRT), an ensemble method for fitting statistical models that differs fundamentally from conventional techniques that aim to fit a single parsimonious model. Boosted regression trees combine the strengths of two algorithms: regression trees (models that relate a response to their predictors by recursive binary splits) and boosting (an adaptive method for combining many simple models to give improved predictive performance). The final BRT model can be understood as an additive regression model in which individual terms are simple trees, fitted in a forward, stagewise fashion. 3 Boosted regression trees incorporate important advantages of tree-based methods, handling different types of predictor variables and accommodating missing data. They have no need for prior data transformation or elimination of outliers, can fit complex nonlinear relationships, and automatically handle interaction effects between predictors. Fitting multiple trees in BRT overcomes the biggest drawback of single tree models: their relatively poor predictive performance. Although BRT models are complex, they can be summarized in ways that give powerful ecological insight, and their predictive performance is superior to most traditional modelling methods. 4 The unique features of BRT raise a number of practical issues in model fitting. We demonstrate the practicalities and advantages of using BRT through a distributional analysis of the short-finned eel (Anguilla australis Richardson), a native freshwater fish of New Zealand. We use a data set of over 13 000 sites to illustrate effects of several settings, and then fit and interpret a model using a subset of the data. We provide code and a tutorial to enable the wider use of BRT by ecologists.

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Adaptation to natural flow regimes

2003-10-22

David A. Lytle , N. LeRoy Poff

Freshwater Ecoregions of the World: A New Map of Biogeographic Units for Freshwater Biodiversity Conservation

2008-05-01

Robin Abell , Michele Thieme , Carmen Revenga +7 more

We present a new map depicting the first global biogeographic regionalization of Earth's freshwater systems. This map of freshwater ecoregions is based on the distributions and compositions of freshwater fish … We present a new map depicting the first global biogeographic regionalization of Earth's freshwater systems. This map of freshwater ecoregions is based on the distributions and compositions of freshwater fish species and incorporates major ecological and evolutionary patterns. Covering virtually all freshwater habitats on Earth, this ecoregion map, together with associated species data, is a useful tool for underpinning global and regional conservation planning efforts (particularly to identify outstanding and imperiled freshwater systems); for serving as a logical framework for large-scale conservation strategies; and for providing a global-scale knowledge base for increasing freshwater biogeographic literacy. Preliminary data for fish species compiled by ecoregion reveal some previously unrecognized areas of high biodiversity, highlighting the benefit of looking at the world's freshwaters through a new framework.

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MECHANISMS CREATING COMMUNITY STRUCTURE ACROSS A FRESHWATER HABITAT GRADIENT

1996-11-01

Gary A. Wellborn , David K. Skelly , Earl E. Werner

▪ Abstract Lentic freshwater habitats in temperate regions exist along a gradient from small ephemeral ponds to large permanent lakes. This environmental continuum is a useful axis for understanding how … ▪ Abstract Lentic freshwater habitats in temperate regions exist along a gradient from small ephemeral ponds to large permanent lakes. This environmental continuum is a useful axis for understanding how attributes of individuals ultimately generate structure at the level of the community. Community structure across the gradient is determined by both (a) physical factors, such as pond drying and winter anoxia, that limit the potential breadth of species distributions, and (b) biotic effects mediated by ecological interactions, principally predation, that determine the realized success of species. Fitness tradeoffs associated with a few critical traits of individuals often form the basis for species turnover along the gradient. Among species that inhabit temporary ponds, distributions are often constrained because traits that enhance developmental rate and competitive ability also increase susceptibility to predators. In permanent ponds, changes in the composition of major predators over the gradient limit distributions of prey species because traits that reduce mortality risk in one region of the gradient cause increased risk in other regions of the gradient. Integrated across the gradient, these patterns in species success generate distinct patterns in community structure. Additionally, spatial heterogeneity among habitats along the gradient and the fitness tradeoffs created by this heterogeneity may hold important evolutionary implications for habitat specialization and lineage diversification in aquatic taxa.

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How much water does a river need?

1997-02-01

Brian D. Richter , Jeffrey V. Baumgartner , Robert Wigington +1 more

1. This paper introduces a new approach for setting streamflow‐based river ecosystem management targets and this method is called the ‘Range of Variability Approach’ (RVA). The proposed approach derives from … 1. This paper introduces a new approach for setting streamflow‐based river ecosystem management targets and this method is called the ‘Range of Variability Approach’ (RVA). The proposed approach derives from aquatic ecology theory concerning the critical role of hydrological variability, and associated characteristics of timing, frequency, duration, and rates of change, in sustaining aquatic ecosystems. The method is intended for application on rivers wherein the conservation of native aquatic biodiversity and protection of natural ecosystem functions are primary river management objectives. 2. The RVA uses as its starting point either measured or synthesized daily streamflow values from a period during which human perturbations to the hydrological regime were negligible. This streamflow record is then characterized using thirty‐two different hydrological parameters, using methods defined in Richter et al . (1996). Using the RVA, a range of variation in each of the thirty‐two parameters, e.g. the values at ± 1 standard deviation from the mean or the twenty‐fifth to seventy‐fifth percentile range, are selected as initial flow management targets. 3. The RVA targets are intended to guide the design of river management strategies (e.g. reservoir operations rules, catchment restoration) that will lead to attainment of these targets on an annual basis. The RVA will enable river managers to define and adopt readily interim management targets before conclusive, long‐term ecosystem research results are available. The RVA targets and management strategies should be adaptively refined as suggested by research results and as needed to sustain native aquatic ecosystem biodiversity and integrity.

Atlantic salmonSalmo salarL., brown troutSalmo truttaL. and Arctic charrSalvelinus alpinus(L.): a review of aspects of their life histories

2003-02-13

Anders Klemetsen , Per‐Arne Amundsen , J. Brian Dempson +4 more

Abstract – Among the species in the family Salmonidae, those represented by the genera Salmo , Salvelinus , and Oncorhynchus (subfamily Salmoninae) are the most studied. Here, various aspects of … Abstract – Among the species in the family Salmonidae, those represented by the genera Salmo , Salvelinus , and Oncorhynchus (subfamily Salmoninae) are the most studied. Here, various aspects of phenotypic and life‐history variation of Atlantic salmon Salmo salar L., brown trout Salmo trutta L., and Arctic charr Salvelinus alpinus (L.) are reviewed. While many strategies and tactics are commonly used by these species, there are also differences in their ecology and population dynamics that result in a variety of interesting and diverse topics that are challenging for future research. Atlantic salmon display considerable phenotypic plasticity and variability in life‐history characters ranging from fully freshwater resident forms, where females can mature at approximately 10 cm in length, to anadromous populations characterised by 3–5 sea‐winter (5SW) salmon. Even within simple 1SW populations, 20 or more spawning life‐history types can be identified. Juveniles in freshwater can use both fluvial and lacustrine habitats for rearing, and while most smolts migrate to sea during the spring, fall migrations occur in some populations. At sea, some salmon undertake extensive oceanic migrations while other populations stay within the geographical confines of areas such as the Baltic Sea. At the other extreme are those that reside in estuaries and return to freshwater to spawn after spending only a few months at sea. The review of information on the diversity of life‐history forms is related to conservation aspects associated with Atlantic salmon populations and current trends in abundance and survival. Brown trout is indigenous to Europe, North Africa and western Asia, but was introduced into at least 24 countries outside Europe and now has a world‐wide distribution. It exploits both fresh and salt waters for feeding and spawning (brackish), and populations are often partially migratory. One part of the population leaves and feeds elsewhere, while another part stays as residents. In large, complex systems, the species is polymorphic with different size morphs in the various parts of the habitat. Brown trout feed close to the surface and near shore, but large individuals may move far offshore. The species exhibits ontogenetic niche shifts partly related to size and partly to developmental rate. They switch when the amount of surplus energy available for growth becomes small with fast growers being younger and smaller fish than slow growers. Brown trout is an opportunistic carnivore, but individuals specialise at least temporarily on particular food items; insect larvae are important for the young in streams, while littoral epibenthos in lakes and fish are most important for large trout. The sexes differ in resource use and size. Females are more inclined than males to become migratory and feed in pelagic waters. Males exploit running water, near‐shore and surface waters more than females. Therefore, females feed more on zooplankton and exhibit a more uniform phenotype than males. The Arctic charr is the northernmost freshwater fish on earth, with a circumpolar distribution in the Holarctic that matches the last glaciation. Recent mtDNA studies indicate that there are five phylogeographic lineages (Atlantic, Arctic, Bering, Siberian and Acadian) that may be of Pleistocene origin. Phenotypic expression and ecology are more variable in charr than in most fish. Weights at maturation range from 3 g to 12 kg. Population differences in morphology and coloration are large and can have some genetic basis. Charr live in streams, at sea and in all habitats of oligotrophic lakes, including very deep areas. Ontogenetic habitat shifts between lacustrine habitats are common. The charr feed on all major prey types of streams, lakes and near‐shore marine habitats, but has high niche flexibility in competition. Cannibalism is expressed in several cases, and can be important for developing and maintaining bimodal size distributions. Anadromy is found in the northern part of its range and involves about 40, but sometimes more days in the sea. All charr overwinter in freshwater. Partial migration is common, but the degree of anadromy varies greatly among populations. The food at sea includes zooplankton and pelagic fish, but also epibenthos. Polymorphism and sympatric morphs are much studied. As a prominent fish of glaciated lakes, charr is an important species for studying ecological speciation by the combination of field studies and experiments, particularly in the fields of morphometric heterochrony and comparative behaviour.

The thermal regime of rivers: a review

2006-07-10

Daniel Caissie

Summary 1. The thermal regime of rivers plays an important role in the overall health of aquatic ecosystems, including water quality issues and the distribution of aquatic species within the … Summary 1. The thermal regime of rivers plays an important role in the overall health of aquatic ecosystems, including water quality issues and the distribution of aquatic species within the river environment. Consequently, for conducting environmental impact assessments as well as for effective fisheries management, it is important to understand the thermal behaviour of rivers and related heat exchange processes. 2. This study reviews the different river thermal processes responsible for water temperature variability on both the temporal (e.g. diel, daily, seasonal) and spatial scales, as well as providing information related to different water temperature models currently found in the literature. 3. Water temperature models are generally classified into three groups: regression, stochastic and deterministic models. Deterministic models employ an energy budget approach to predict river water temperature, whereas regression and stochastic models generally rely on air to water temperature relationships. 4. Water temperature variability can occur naturally or as a result of anthropogenic perturbations, such as thermal pollution, deforestation, flow modification and climate change. Literature information is provided on the thermal regime of rivers in relation to anthropogenic impacts and such information will contribute to the better protection of fish habitat and more efficient fisheries management.

Habitat Structural Complexity and the Interaction Between Bluegills and Their Prey

1982-12-01

Larry B. Crowder , William E. Cooper

Structural complexity of the habitat often reduces predatory efficiency by reducing prey capture rates. Prey density is often positively correlated with habitat structure because it pro- vides food and substrate … Structural complexity of the habitat often reduces predatory efficiency by reducing prey capture rates. Prey density is often positively correlated with habitat structure because it pro- vides food and substrate to the prey as well as a relative refuge from predators. Dense structure inhibits foraging, allowing abundant, highly profitable prey to coexist with predators. Sparse structure allows efficient foraging and generally contains few highly profitable prey. This suggests that feeding rates of predators may be maximized at intermediate structure. If this is true, we might also expect predator growth rates to be higher in intermediate structure habitats. Since diet breadth is thought to be related to rates of encounter with profitable prey, we also expect diets of predators to be narrower at intermediate structure than in either sparsely or densely structured habitats. Bluegill sunfish (Lepomis macrochirus) restricted to experimental ponds varying in vegetation density grew better and consumed more prey at intermediate macrophyte density than fish held at either low or high macrophyte densities. Fish at low macrophyte density had narrower diets than expected due to high initial prey availability relative to prey available at intermediate and high macro- phyte density. Fish at high macrophyte density ate fewer, but larger, prey and thus had a narrower diet than expected. Fish predation reduced total prey biomass as well as mean prey size and altered the prey community structure by removing large active invertebrate predators and herbivores with subsequent release of smaller invertebrate predators and herbivores. These changes in prey com- munity structure were also mediated by habitat structure. Habitat structure-food density interactions may be added to temperature and presence of predators as variables that influence the use of resources by fishes.

Pacific Salmon Life Histories

1992-08-18

Thomas P. Quinn , C. Groot , Leo Margolis

Preface / C. Groot and L. Margolis Life History of Sockeye Salmon / Robert L. Burgner, University of Washington Life History of Pink Salmon / William R. Heard, Auke Bay … Preface / C. Groot and L. Margolis Life History of Sockeye Salmon / Robert L. Burgner, University of Washington Life History of Pink Salmon / William R. Heard, Auke Bay Fisheries Laboratory, Alaska Life History of Chum Salmon / E.O. Salo, University of Washington Life History of Chinook Salmon / M.C. Healey, University of British Columbia Life History of Coho Salmon / F.K. Sandercock, Department of Fisheries and Oceans, Canada Life Histories of Masu and Amago Salmon / Fumihiko Kato, National Institute of Fisheries Science, Japan Indexes

The Length-Weight Relationship and Seasonal Cycle in Gonad Weight and Condition in the Perch (Perca fluviatilis)

1951-11-01

E. D. Le Cren

Biological Integrity: A Long‐Neglected Aspect of Water Resource Management

1991-02-01

James R. Karr

Water of sufficient quality and quantity is critical to all life. Increasing human population and growth of technology require human society to devote more and more attention to protection of … Water of sufficient quality and quantity is critical to all life. Increasing human population and growth of technology require human society to devote more and more attention to protection of adequate supplies of water. Although perception of biological degradation stimulated current state and federal legislation on the quality of water resources, that biological focus was lost in the search for easily measured physical and chemical surrogates. The "fishable and swimmable" goal of the Water Pollution Control Act of 1972 (PL 92—500) and its charge to "restore and maintain" biotic integrity illustrate that law's biological underpinning. Further, the need for operational definitions of terms like "biological integrity" and "unreasonable degradation" and for ecologically sound tools to measure divergence from societal goals have increased interest in biological monitoring. Assessment of water resource quality by sampling biological communities in the field (ambient biological monitoring) is a promising approach that requires expanded use of ecological expertise. One such approach, the Index of Biotic Integrity (IBI), provides a broadly based, multiparameter tool for the assessment of biotic integrity in running waters. IBI based on fish community attributes has now been applied widely in North America. The success of IBI has stimulated the development of similar approaches using other aquatic taxa. Expanded use of ecological expertise in ambient biological monitoring is essential to the protection of water resources. Ecologists have the expertise to contribute significantly to those programs.

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Emerging threats and persistent conservation challenges for freshwater biodiversity

2018-11-22

Andrea J. Reid , Andrew K. Carlson , Irena F. Creed +7 more

ABSTRACT In the 12 years since Dudgeon et al . (2006) reviewed major pressures on freshwater ecosystems, the biodiversity crisis in the world's lakes, reservoirs, rivers, streams and wetlands has … ABSTRACT In the 12 years since Dudgeon et al . (2006) reviewed major pressures on freshwater ecosystems, the biodiversity crisis in the world's lakes, reservoirs, rivers, streams and wetlands has deepened. While lakes, reservoirs and rivers cover only 2.3% of the Earth's surface, these ecosystems host at least 9.5% of the Earth's described animal species. Furthermore, using the World Wide Fund for Nature's Living Planet Index, freshwater population declines (83% between 1970 and 2014) continue to outpace contemporaneous declines in marine or terrestrial systems. The Anthropocene has brought multiple new and varied threats that disproportionately impact freshwater systems. We document 12 emerging threats to freshwater biodiversity that are either entirely new since 2006 or have since intensified: ( i ) changing climates; ( ii ) e‐commerce and invasions; ( iii ) infectious diseases; ( iv ) harmful algal blooms; ( v ) expanding hydropower; ( vi ) emerging contaminants; ( vii ) engineered nanomaterials; ( viii ) microplastic pollution; (i x ) light and noise; ( x ) freshwater salinisation; ( xi ) declining calcium; and ( xii ) cumulative stressors. Effects are evidenced for amphibians, fishes, invertebrates, microbes, plants, turtles and waterbirds, with potential for ecosystem‐level changes through bottom‐up and top‐down processes. In our highly uncertain future, the net effects of these threats raise serious concerns for freshwater ecosystems. However, we also highlight opportunities for conservation gains as a result of novel management tools (e.g. environmental flows, environmental DNA) and specific conservation‐oriented actions (e.g. dam removal, habitat protection policies, managed relocation of species) that have been met with varying levels of success. Moving forward, we advocate hybrid approaches that manage fresh waters as crucial ecosystems for human life support as well as essential hotspots of biodiversity and ecological function. Efforts to reverse global trends in freshwater degradation now depend on bridging an immense gap between the aspirations of conservation biologists and the accelerating rate of species endangerment.

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Mapping the world’s free-flowing rivers

2019-05-08

Günther Grill , Bernhard Lehner , Michele Thieme +7 more

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Freshwater Fishes of Canada

1974-12-31

J. E. M. , W. B. Scott , E. J. Crossman

Ecological Methodology

1984-01-01

Geraint Parry , Michael S. Johnson , R. M. Bell +2 more

Commissioned surveys and staff surveys and reports for Scottish Wildlife Trust reserves - Verified data

2022-01-01

Registry-Migration.Gbif.Org

This dataset comprises species recorded on Scottish Wildlife Trust reserves through individual surveys commissioned or undertaken by the Trust. Records in this dataset have undergone a level of verification, either … This dataset comprises species recorded on Scottish Wildlife Trust reserves through individual surveys commissioned or undertaken by the Trust. Records in this dataset have undergone a level of verification, either using the rules provided by national recording schemes and societies available via the NBN Record Cleaner, or other experts, such as Vice County Recorders. These data are provided "as is" and Scottish Wildlife Trust do not have the resources to interpret these data. The Trust would recommend using a Local Record Centre for interpretation purposes and to gain a clear picture of all datasets available, many of which will not yet be on the NBN Atlas.

The Influence of Multiple Delays on the Dynamics of Plankton‐Fish System

2025-06-25

Renxiang Shi | Mathematical Methods in the Applied Sciences

ABSTRACT This paper studies the dynamics of a plankton‐fish system with three delays. First, we prove the positivity and boundedness of solutions. Then, under three cases: one delay, two delays, … ABSTRACT This paper studies the dynamics of a plankton‐fish system with three delays. First, we prove the positivity and boundedness of solutions. Then, under three cases: one delay, two delays, and three delays, we discuss the influence of multiple delays on the dynamics by theoretical analysis and simulation. At last, in absence and presence of delays, we give the influence of fear effect on the dynamics by simulations. Our results reveal that both delays and fear effect bring rich dynamics for plankton‐fish system, such as periodic oscillation and chaos.

Aquatic insect functional traits indicate spatiotemporal changes in potential aquatic prey availability to terrestrial consumers after small dam removal

2025-06-24

Peter Carlson | Journal of Freshwater Ecology

Seasonal movements of adult Gizzard Shad Dorosoma cepedianum in a Missouri River reservoir

2025-06-24

Kayla Reed , Justin A. VanDeHey , Hilary Morey +3 more | Journal of Freshwater Ecology

Estimating drivers and identifying uncertainties in smallmouth bass population dynamics in an invaded river network

2025-06-24

Lindsey A. Bruckerhoff , Charles B. Yackulic , Drew E. Eppehimer +3 more | Canadian Journal of Fisheries and Aquatic Sciences

Smallmouth bass (Micropterus dolomieu) is an important recreational sportfish and destructive non-native species when introduced into freshwater habitats. There is therefore a need to understand the drivers of, and uncertainties … Smallmouth bass (Micropterus dolomieu) is an important recreational sportfish and destructive non-native species when introduced into freshwater habitats. There is therefore a need to understand the drivers of, and uncertainties in, smallmouth bass population dynamics for various management objectives. We combined long-term smallmouth bass catch-effort and early life history data from a non-native population in the Green River sub-basin of the upper Colorado River to develop a demographic model that links interannual variability in environmental conditions to recruitment in three river reaches. We used the model to quantify how hydrology, river temperature, and exploitation drive smallmouth bass population dynamics. Early life stages were influenced by timing of hatching and discharge. Dispersal of age-0 fish and density-dependent dynamics were identified as primary sources of uncertainty. Determining the true nature of density-dependent dynamics is important, as the impact of exploitation-based management actions is dependent on the strengths of any density-dependent feedbacks. Our model provides a framework to predict smallmouth bass population responses to future climate conditions, reservoir operations, and exploitation levels.

Editor's Note: Three Decades of World Recreational Fishing Conferences: What Have We Learned About the Dynamics of Recreational Fisheries?

2025-06-24

| Fisheries Management and Ecology

A Comparison of Trap-Baiting Methods for Sampling Aquatic and Semi-Aquatic Fauna in the Southeastern United States

2025-06-23

Evan S. Grimes , Matthew W. H. Chatfield | Southeastern Naturalist

The long-term effect of non-invasive sampling on the genetic diversity and growth performance of cultured Gymnocypris chilianensis (Cyprinidae) population: an evaluation based on 70 days

2025-06-23

B. Liu , Qiqun Cheng , Zhongyu Lou +3 more | Israeli Journal of Aquaculture - Bamidgeh

Non-invasive and non-lethal sampling methods are widely employed in conservation biology, but their long-term effects on sampled organisms remain understudied. To evaluate these impacts on fish and establish a scientific … Non-invasive and non-lethal sampling methods are widely employed in conservation biology, but their long-term effects on sampled organisms remain understudied. To evaluate these impacts on fish and establish a scientific framework for ethical sampling practices, we conducted a dual investigation using the plateau-endemic species Gymnocypris chilianensis (Cyprinidae). First, genetic diversity in a cultured population was analyzed using non-invasive mucus sampling. Sequencing of mitochondrial Cytb (1098 bp) and D-loop (696 bp) regions revealed low genetic diversity, with Cytb showing six polymorphic sites, seven haplotypes (haplotype diversity H = 0.354; nucleotide diversity π = 0.0004), and D-loop displaying 10 polymorphic sites, 9 haplotypes (H = 0.787; π = 0.00315). The D-loop region demonstrated higher variability, supporting its utility as a marker for population genetic studies. Second, 180 individuals were divided into three groups, i.e., groups N (macus), Q (fin), and C (control), and monitored for 70 days to assess growth parameters (standard length, body weight), condition factor (K), and mortality. Generalized additive models (GAMs) revealed no significant differences in morphological indicators (p > 0.05) or mortality rates among groups, with a nonlinear standard length–weight regression relationship identified. Notably, all groups exhibited K values exceeding 200%, indicating excellent body condition. Comparative analyses confirmed minimal sequence divergence between non-invasive and traditional sampling methods, validating methodological reliability. This study provides the first long-term evaluation of non-invasive and non-lethal sampling impacts on fish growth, the results showed that non-invasive sampling had no significant impact on the growth or survival of fish, which was very important for future research and protection, combined with genetic diversity insights, offering critical guidelines for conserving vulnerable species like G. chilianensis in the Qinghai-Tibet Plateau.

NUCLEAR ANOMALIES AND MICRONUCLEI IN PERIPHERAL BLOOD ERYTHROCYTES OF CYPRINID FISH IN RIVERS WITH NATURAL AND ALTERED THERMAL REGIMES (BERYOZOVKA AND TEPLAYA RIVERS, YENISEI RIVER BASIN)

2025-06-23

N. A. Yablokov | Ekosistemy

The paper presents data on the occurrence of micronuclei and nuclear anomalies in peripheral blood erythrocytes of three carp species: the gudgeon Gobio gobio (Linnaeus, 1759), the Eurasian minnow Phoxinus … The paper presents data on the occurrence of micronuclei and nuclear anomalies in peripheral blood erythrocytes of three carp species: the gudgeon Gobio gobio (Linnaeus, 1759), the Eurasian minnow Phoxinus phoxinus (Linnaeus, 1758), and the sunbleak Leucaspius delineatus (Heckel, 1843)). These species inhabit rivers with both natural (Beryozovka River) and altered thermal regimes (Teplaya River). During the study, an extensive list of nuclear anomalies – 20 and 22 types, respectively – was found in the erythrocytes of fish from both the Teplaya and Beryozovka Rivers. The occurrence of abnormal nuclei in erythrocytes of the three studied fish species from the Teplaya River averaged 1.52±0.25–2.61±0.91 %, while in fish from the Beryozovka River, it ranged from 2.27±0,63–3.53±0.97 %. The assessment of the significance of differences between the occurrences of anomalies revealed no statistically significant differences among individuals of each of the fish species from the two studied watercourses. The values of the Mann-Whitney test (U) for the gudgeon samples were 74.0 (p=0.45), for the Eurasian minnow were 39.0 (p=0.43), and for the sunbleak were 29.0 (p= 0.96). Despite the absence of statistically significant differences, variations in the occurrence of specific types of anomalies were observed among the erythrocyte samples. Based on the obtained data, an assumption was made that the intensity of anomalies in the erythrocyte nuclei of carp fish living in the Teplaya River was influenced more by hydrochemical factors than by the altered thermal regime.

Restoring free‐flowing rivers: Planning for longitudinal and lateral connectivity recovery

2025-06-23

Virgilio Hermoso | Journal of Applied Ecology

Abstract Spatial–temporal connectivity is a key feature defining functional freshwater ecosystems but has been deeply transformed worldwide by longitudinal barriers, like dams, weirs or culverts and lateral barriers such as … Abstract Spatial–temporal connectivity is a key feature defining functional freshwater ecosystems but has been deeply transformed worldwide by longitudinal barriers, like dams, weirs or culverts and lateral barriers such as levees or channels, which have interrupted longitudinal continuity and disconnected rivers from their floodplains, respectively. There is growing interest in restoring the natural functionality of rivers and streams recovering free‐flowing rivers, as these infrastructures threaten the maintenance of ecological processes that sustain biodiversity and ecosystem services. This recovery must be supported by adequate planning, often in entire catchments, to overcome the limitations of traditional opportunistic decisions, which have dragged the effectiveness of past river restoration. Most of the restoration planning efforts have focused on longitudinal connectivity. However, the recovery of free‐flowing rivers demands that future restoration efforts also consider other dimensions of connectivity. I demonstrate how to plan for the recovery of longitudinal and lateral connectivity by identifying priority longitudinal and lateral barriers for restoration, to recover connectivity between populations of freshwater fish and floodplain habitats, while minimising the opportunity cost of restoration efforts. I test the approach under four alternative scenarios, including a coordinated vs. an uncoordinated scenario, where both types of barriers are simultaneously or individually prioritised. I also explored a null cost scenario where all barriers had the same opportunity cost, and a locked out scenario where barriers with a high opportunity cost were not allowed for selection, both under coordinated conditions. The results show that coordinated planning taking into account the opportunity costs of barriers leads to recommendations with the best perspective for the ecological recovery of free‐flowing rivers, with lateral barriers selected in combination with longitudinal barriers upstream to allow recovery of the functionality of floodplains reconnected to rivers, while minimising the opportunity cost of restoration. Synthesis and Applications . Adequate planning should guide decision making in complex scenarios like river restoration, where opportunistic approaches have proven ineffective. This includes setting clear objectives and constraints and using adequate data. Restoring free‐flowing rivers will also need the restoration of more than longitudinal connectivity, which will benefit from integrated planning of multiple types of barriers simultaneously.

Quantitative Assessment of Local Siltation Dynamics in Multi-Anabranching River System: Case Studies of Representative Port in the Lower Yangtze River and Engineering Interventions

2025-06-23

Ke Zheng , Yuncheng Wen , Fanyi Zhang +4 more | Water

The Ma’anshan section of the lower Yangtze River features a complex multi-anabranching system, where the river divides into several branches around mid-channel sandbars, with distinct point bars alternately developing along … The Ma’anshan section of the lower Yangtze River features a complex multi-anabranching system, where the river divides into several branches around mid-channel sandbars, with distinct point bars alternately developing along both banks. Within this morphologically active system, Zhengpu Harbor suffered severe operational disruptions by accelerated siltation at its approach channel, primarily due to its vulnerable location downstream of the expanding Niutun River point-bar on the left bank. To systematically diagnose the mechanisms of siltation, this study integrates multi-method investigations: decadal-scale morphodynamic analysis using long-term bathymetric surveys, numerical modeling to quantify engineering impacts on flow dynamics, and multiple linear regression analysis for the contributions of key influencing factors. The result identifies three primary drivers of siltation, collectively responsible for 70% of the sediment accumulation, including the rightward shift of the thalweg in the Ma’anshan left branch, reduced flow diversion of the left Branch of Central bar, and the expansion of the Niutun River point bar. River engineering structures, such as bridges, contribute approximately 12%, while changes in upstream flow-sediment supply account for approximately 18%. To mitigate siltation at Zhengpu Harbor’s approach channel, this study proposes targeted engineering interventions to enhance local hydrodynamic conditions. The spur dikes were designed to enhance the morphological stabilization of the Central bar head to regulate flow distribution. A diversion channel could also be excavated at the tail of the Niutun River shoal, and emergency dredging was recommended at the harbor front. Numerical modeling indicates that these measures will increase flow velocity by over 0.1 m/s at the harbor front, mitigating the siltation situation. The study concludes that the proposed engineering measures can reduce annual siltation by approximately 30% under normal-year hydrological conditions, demonstrating their feasibility in mitigating siltation trends in multi-anabranching river systems. This research provides a reference for addressing siltation issues in harbors within complex anabranching river systems.

How microhabitat characteristics influence the females’ nest site selection of the invasive alien species Trachemys scripta in the Angitola Lake (Calabria, Southern Italy)

2025-06-23

Francesco Luigi Leonetti , Antonio Crescente , C. Valerioti +4 more | The European Zoological Journal

Niche Partitioning Among Three Apex Piscivorous Fishes: Evidence of Limited Intraguild Predation

2025-06-21

Robert W. Eckelbecker , Christopher S. Guy , Paul C. Gerrity +3 more | Ecology Of Freshwater Fish

ABSTRACT This study aimed to understand the ecological relationship among burbot Lota lota , brown trout Salmo trutta and lake trout Salvelinus namaycush , with a focus on burbot, a … ABSTRACT This study aimed to understand the ecological relationship among burbot Lota lota , brown trout Salmo trutta and lake trout Salvelinus namaycush , with a focus on burbot, a species of greatest conservation need in Wyoming. While we hypothesised a reciprocal intraguild predation dynamic, where competition and predation occur between predators based on size or age structure, our findings provided limited support for this hypothesis. Both dietary overlap and trophic position were minimal among burbot, brown trout and lake trout. Instances of reciprocal predation were rare; no predation between burbot and lake trout was observed; and brown trout was the only species consumed by all predators (burbot 0.02 mean proportion by weight; lake trout 0.09 mean proportion by weight). Predation by brown trout on burbot was negligible, contributing only 0.01 to the mean proportion by weight and frequency of occurrence. Additionally, both burbot and brown trout were less piscivorous than expected, with fish comprising 0.36 and 0.17 of their mean proportion by weight in their overall diets, respectively. Overall, our findings suggest that these predators coexist with limited competitive or predatory interactions, likely due to differences in prey selection.

Environmental factors regulating temporal pattern of fish community and declining threats in the Khaliajuri haor wetland of Bangladesh

2025-06-21

Md. Nahiduzzaman , Ehsanul Karim , Anuradha Bhadra +1 more | Environmental Science and Pollution Research

The Biwa salmon, a new species of Oncorhynchus (Salmonidae) endemic to Lake Biwa, Japan

2025-06-21

Yasuhiro Fujioka , Masayuki Kuwahara , Ryoichi Tabata +2 more | Ichthyological Research

A Simplified Method for Extracting the Movement Trajectories of Small Aquatic Animals

2025-06-20

Xin Liu , Huanan Gao , Aimin Hao +1 more | Methods and Protocols

Understanding the motion behaviors of animals is crucial for unraveling the mechanisms underlying ethology across various domains, such as movement patterns, food detection, and defense strategies. In this study, we … Understanding the motion behaviors of animals is crucial for unraveling the mechanisms underlying ethology across various domains, such as movement patterns, food detection, and defense strategies. In this study, we devised a simplified method enabling the movement of small animals to be tracked conveniently using high-resolution smartphone videos and freely available tracking software. Employing a laboratory video setup, we traced the swimming trajectory of the small copepod zooplankton Eodiaptomus japonicus, which has a body size of approximately 1 mm. From the tracked position data, we analyzed key motion parameters, including swimming distance, speed, and jump frequency. The results of our video analysis showed that adult female E. japonicus exhibited an average swimming speed of 9.8 mm s−1, displaying a predominant cruising pattern with speeds of around 5.0 mm s−1, punctuated by sporadic jumps, showcasing maximum instantaneous speeds reaching a remarkable 190.1 mm s−1. Our successful tracking of the high-speed swimming copepod not only sheds light on its locomotion dynamics but also underscores the potential to refine this method to study the motion trajectories of diverse animal species.

Empirische Modelle zur Vorhersage der Überlebensraten von Fischen in Kaplan-Turbinen

2025-06-20

Walter Reckendorfer , Josef Schneider | Österreichische Wasser- und Abfallwirtschaft

Zusammenfassung Für den Schutz von Fischpopulationen vor Turbinen bedingten Schädigungen stehen verschiedene Möglichkeiten zur Verfügung, darunter mechanische Barrieren, Verhaltensbarrieren, elektrische Scheuch-Einrichtungen oder ökologische Maßnahmen. Um geeignete Fischschutzmaßnahmen zu identifizieren, sind … Zusammenfassung Für den Schutz von Fischpopulationen vor Turbinen bedingten Schädigungen stehen verschiedene Möglichkeiten zur Verfügung, darunter mechanische Barrieren, Verhaltensbarrieren, elektrische Scheuch-Einrichtungen oder ökologische Maßnahmen. Um geeignete Fischschutzmaßnahmen zu identifizieren, sind Informationen hinsichtlich der Überlebensraten verschiedener Fischarten und Lebensstadien bei Turbinenpassage eine wertvolle Entscheidungsgrundlage. Für Kaplan-Turbinen stehen dafür mehrere empirische Formeln zur Verfügung, deren Anwendung jedoch begrenzt ist, da die zugrunde liegenden Daten und der Entwicklungsprozess unzureichend dokumentiert sind. Das Hauptziel dieser Studie war daher die Entwicklung empirischer Formeln auf Basis eines transparenten Entwicklungsprozesses und unter Verwendung einfacher bzw. bekannter Parameter. Basierend auf Daten aus 276 In-situ-Injektionsversuchen, die in der Fachliteratur und in der „grauen“ Literatur verfügbar sind, haben wir mehrere neue Formeln zur Abschätzung der Überlebensrate von Fischen entwickelt und anhand ihrer Wahrscheinlichkeit gereiht. Die neu entwickelten Formeln können mit ausreichender Genauigkeit Vorhersagen hinsichtlich der Überlebensraten von Fischen bei Turbinenpassage treffen. Sie bestätigen die bekannten Zusammenhänge mit Fischgröße und Turbinenparametern, allerdings gibt es auch Hinweise auf einen Einfluss weiterer Faktoren wie Form und Physiologie der Fische.

Spatial–temporal variation in the vertical behaviour of sea trout kelts during their marine phase

2025-06-20

Céline Artero , Jessica E. Marsh , William A. Beaumont +2 more | Reviews in Fish Biology and Fisheries

Abstract Sea trout, the anadromous form of brown trout ( Salmo trutta ), migrate from freshwater to coastal and offshore habitats for increased feeding and growth opportunities and ultimately, reproductive … Abstract Sea trout, the anadromous form of brown trout ( Salmo trutta ), migrate from freshwater to coastal and offshore habitats for increased feeding and growth opportunities and ultimately, reproductive success. However, knowledge of habitat use and behaviour in the marine environment is limited, particularly for post-spawners (kelts). In this study, we used data collected from 63 sea trout kelts that were double tagged with acoustic and data storage tags, caught in three rivers feeding into the English Channel (rivers Tamar and Frome in southern England and Bresle in northern France) to describe depth use and diving behaviour at sea as a function of a suite of abiotic and biotic variables. Diving activity mostly occurred during daylight hours across all rivers, but we also identified population-specific behaviours with regards to diving frequency and depth as well as the relationship between size of fish and vertical behaviour. While we found distinct diel vertical behaviour consistent with existing literature on sea trout populations at higher latitudes, we showed kelts in this study to use relatively deeper water during the marine phase. This work contributes to limited knowledge of adult sea trout behaviour at sea and indicates necessary considerations for managing anthropogenic impacts at sea on this important life-stage.

Operative tagging of sturgeon brood stock

2025-06-19

S. B. Podushka | Fisheries

The article describes a simple procedure for the rapid tagging of sturgeon producers during spawning season. Tagging is performed by punching holes in the pectoral fins using veterinary forceps. The article describes a simple procedure for the rapid tagging of sturgeon producers during spawning season. Tagging is performed by punching holes in the pectoral fins using veterinary forceps.

Impacts of Rising Water Temperatures on Reproductive Physiology and Spawning Success in Indigenous Riverine Fish Species

2025-06-19

Kush Patel | Asian Journal of Research in Zoology

The increasing global temperatures driven by climate change have significant implications for freshwater ecosystems, particularly impacting the reproductive physiology and spawning success of indigenous riverine fish species. This study investigates … The increasing global temperatures driven by climate change have significant implications for freshwater ecosystems, particularly impacting the reproductive physiology and spawning success of indigenous riverine fish species. This study investigates how rising water temperatures influence key reproductive parameters, including gonadal development, hormonal regulation, spawning behavior, and egg viability in native fish populations. Elevated temperatures were found to disrupt endocrine signaling pathways, notably reducing levels of gonadotropins and sex steroids essential for gametogenesis. Histological examinations revealed delayed oocyte maturation and increased incidence of atretic follicles in females, alongside reduced sperm quality in males. Moreover, altered thermal regimes shortened the reproductive window and shifted spawning seasons, potentially leading to a mismatch with optimal environmental cues required for successful reproduction. Field observations and controlled laboratory experiments across multiple species, including Labeo rohita, Catla catla, and Tor putitora, indicated a marked decline in spawning frequency and fry survival rates at temperatures 2–3°C above historical norms. These changes not only threaten the sustainability of native fish populations but also have cascading effects on aquatic biodiversity and fisheries-based livelihoods. This study underscores the urgency of developing adaptive conservation strategies and thermal management practices to mitigate the effects of climate warming on freshwater reproductive ecology.

Reflections on Canada’s 2005 Wild Pacific Salmon Policy (WSP) With Suggestions Going Forward

2025-06-19

James R. Irvine | Canadian Journal of Fisheries and Aquatic Sciences

This paper highlights the need for more integrated and strategic planning to conserve Canada’s wild Pacific salmon amidst climate change. Two decades after the release of the WSP, which shifted … This paper highlights the need for more integrated and strategic planning to conserve Canada’s wild Pacific salmon amidst climate change. Two decades after the release of the WSP, which shifted management focus away from fisheries to the restoration and maintenance of ecologically and/or genetically distinct units of diversity (i.e., Conservation Units (CUs)), salmon (including steelhead) populations continue to decline. Reasons are diverse but generally well-known. Of many suggestions going forward, the author highlights the need to: 1) expand the vision for domestic salmon management that maintains an overall focus on conservation while acknowledging that socioeconomic benefits sometimes take precedence; 2) set realistic goals for all Conservation and Stock Management Units recognizing the constraints imposed by a changing climate; 3) develop a structured decision-making process that defines measurable actions to achieve these goals while considering individual CU status; 4) strengthen Canadian leadership to build international consensus on density dependent effects of competition in the marine environment and appropriate responses; and 5) ensure adequate stable funding to monitor salmon populations and their ecosystems, with findings readily accessible.

Community science helps digitize 78 years of fish and habitat data for thousands of lakes in Michigan, USA

2025-06-19

Katelyn King , Justin Schell , Kevin E. Wehrly +5 more | Scientific Data

The state of Atlantic salmon stocks (Salmo-SalarL.) of the Tuloma river (Kola Peninsula)

2025-06-19

A. V. Tkachenko , А. В. Зубченко | Fisheries

Long-term abundance dynamics of Atlantic salmon in the Tuloma River were analyzed. It was an opinion given that the Nizhne-Tulomskaya and Verkhne-Tulomskaya hydropower plants have no significant impact on the … Long-term abundance dynamics of Atlantic salmon in the Tuloma River were analyzed. It was an opinion given that the Nizhne-Tulomskaya and Verkhne-Tulomskaya hydropower plants have no significant impact on the reproductive capacity in the river. Ulcerative dermal necrosis causing spawners mortality and illegal fisheries were also considered to have an impact on the abundance dynamics. It was concluded that all these cumulatively have recently had a negative impact on the stock. Being the cause of mass mortality of juveniles in Norwegian rivers and in the Keret’ River (Russia), monogenean Gyrodactylus salaris was detected and identified as a risk factor. A number of practical measures were suggested to restore the stock abundance up to the long-term means.

Evaluating Environmental Predictors of Fish Community Composition in a Semi‐Arid River System Using a Model‐Based Approach

2025-06-19

Mojgan Zare Shahraki , Pejman Fathi , Sami Domisch +4 more | Ecology Of Freshwater Fish

ABSTRACT Understanding how the environment shapes species distribution and affects biodiversity patterns is important in ecology and conservation. Environmental stressors like climate change and anthropogenic impacts may lead to a … ABSTRACT Understanding how the environment shapes species distribution and affects biodiversity patterns is important in ecology and conservation. Environmental stressors like climate change and anthropogenic impacts may lead to a significant decline in aquatic biodiversity. Therefore, it is imperative to characterise the current community structure and explore environmental drivers that may be important for the future community structure, also in biogeographic areas that are largely outside of the main research focus. We investigated how fish species abundances in the Karun River basin, southwest of Iran, respond to environmental predictors along a longitudinal gradient of 108 sampling sites using Generalised Linear Latent Variable Models (GLLVMs). We evaluated the response of 46 fish species to seven environmental predictors and interpreted the bivariate species co‐occurrences in the residual covariance matrix in the light of potential biotic interactions. The latent variable model explained 62% of data variability in fish abundance. We identified temperature as the most important predictor, with alien species responding positively to warmer conditions, suggesting potential distribution shifts due to climate change. In contrast, endemic species showed negative responses to higher temperatures, highlighting their vulnerability. Fish abundance responses to total nitrogen concentration and average precipitation were generally negative, indicating threats from nutrient enrichment and changing rainfall patterns. There were a few systematic negative co‐occurrences between alien and native fish species, which may reflect both differing environmental preferences and potential negative interactions. The model showed high predictive accuracy for the occurrence of native species, while accuracy was lower for endemic and alien species, likely due to their more limited geographical distributions. This study contributes to the global understanding of how environmental drivers shape fish communities in semi‐arid river systems. By highlighting the contrasting responses of endemic and alien species to selected stressors, it provides valuable insights for predicting and managing biodiversity under climate change, offering a framework applicable to similar ecosystems worldwide.

Effects of Nest Exclosure on Nest and Adult Survival of Piping Plover (Charadrius melodus) in the Lower Platte River System, Nebraska

2025-06-19

Elsa M. Forsberg , Joel G. Jorgensen , Rose J. Swift +2 more | Waterbirds

Effects of Biological Characteristics and Environmental Factors on Swimming Performance of Endemic Fish in Southwest China

2025-06-19

J. N. Rao , Zhiguang Zhang , Yuanming Wang +5 more | Animals

Swimming is crucial to fish survival and reproduction, and is usually influenced by species, morphology, habitat environment and physiological condition. Understanding the changes in fish swimming ability and identifying the … Swimming is crucial to fish survival and reproduction, and is usually influenced by species, morphology, habitat environment and physiological condition. Understanding the changes in fish swimming ability and identifying the driving factors behind these changes is vital. In this study, seven endemic fish species from the Qingshui River, an important tributary of the upper Pearl River in Southwest China, were used to explore the effects of biological and environmental factors on fish swimming ability. The results indicated that the body length parameters had a minimal effect on the induced swimming speed (Uind) but played a positive role in critical and burst swimming ability (Ucrit and Uburst). Weight (W) and W/SL (the ratio of weight to standard body length) correlated more highly with swimming ability than body length parameters. Fish preferring the lotic environment exhibited higher Ucrit and Uburst, and fish with a streamlined morphology had a smaller Uind. The Uind, Uind/SL, Uind/W and Uind/(W/SL) of Discogobio yunnanensis (Regan, 1907) and Pseudocrossocheilus tridentis (Cui & Chu, 1986) were significantly higher during the spawning period. Acrossocheilus yunnanensis (Regan, 1904) performed better during the spawning period in Ucrit and Ucrit/SL. The Uburst of fish during the spawning period was smaller than that during the non-spawning period. Generally, the species difference had the greatest contribution to the swimming ability difference, followed by environmental conditions and fish morphology.

First case of parthenogenesis in an intersexual zebra shark (<scp>Stegostoma tigrinum</scp>) having incomplete claspers

2025-06-18

Kazuyuki Momota , Itsuki Kiyatake , Takeshi Izawa +3 more | Journal of Fish Biology

Abstract Parthenogenesis, where reproduction occurs without fertilization by a male, and intersexuality, where an individual exhibits both male and female characteristics, have occasionally been observed in elasmobranchs. Although parthenogenesis has … Abstract Parthenogenesis, where reproduction occurs without fertilization by a male, and intersexuality, where an individual exhibits both male and female characteristics, have occasionally been observed in elasmobranchs. Although parthenogenesis has been previously documented in zebra sharks ( Stegostoma tigrinum ), no individual with intersexuality has been reported. The female S. tigrinum [2060 mm total length (TL)], with incomplete claspers, laid 30 eggs in 2018 at the Osaka Aquarium NIFREL after 2 years and 5 months of monosex rearing. Embryonic development was confirmed in eight of these eggs, resulting in the successful hatching of one individual (253.8 mm TL). Its claspers exhibited incomplete external and internal structures, and its ovary contained scattered sperm duct‐like structures without any evidence of spermatogenesis. Consequently, the present specimen was classified as having basic intersexuality. Furthermore, an analysis of 14 microsatellite loci in the hatching juvenile revealed complete maternal homozygosity across all loci, indicating parthenogenesis. This is the first report of parthenogenesis in an intersex individual. Our results play an important role in enhancing our understanding of the diversity of shark reproduction.

On the behavior of Fish Released Following Fisheries Capture: Methods, Endpoints, and Consequences

2025-06-18

Luc LaRochelle , Lucas P. Griffin , Jacob W. Brownscombe +7 more | Reviews in Fisheries Science & Aquaculture

Culvert baffle design to improve fish passage for small‐bodied fishes: A rapid evidence synthesis

2025-06-18

P.A. Franklin , Cindy F. Baker | Conservation Science and Practice

Abstract Culverts are one of the most prevalent barriers to the upstream movement of small‐bodied fishes. Installation of baffles, structures designed to modify flows, within culverts is one of the … Abstract Culverts are one of the most prevalent barriers to the upstream movement of small‐bodied fishes. Installation of baffles, structures designed to modify flows, within culverts is one of the main solutions for overcoming the impact of high water velocities on fish movements. The objective of this rapid evidence synthesis was to review and summarize the evidence on the effectiveness of different culvert baffle designs for improving the abundance and diversity of small‐bodied fish successfully migrating upstream through culverts. The overall weight of evidence indicates that the addition of baffles generally increases overall passage success compared with control treatments with no baffles. However, effectiveness cannot be determined based on simple passage efficiency metrics alone. Multiple lines of evidence are emerging to indicate that turbulence within baffle arrays can significantly delay upstream movements. A consensus is emerging that baffles that minimize the generation of large recirculation zones while maximizing the area of low‐velocity boundary layers (i.e., spoiler, vertical, and longitudinal baffles) are most suitable for improving the upstream passage of small‐bodied fishes. However, there remain significant knowledge gaps and an urgent need for comparative assessments of baffle performance alongside ongoing innovation to refine and optimize baffle designs for small‐bodied species.

Nymphal biology of Antarctoperla michaelseni (Klapálek, 1904) and Klapopteryx armillata Navás, 1928 in an Andean stream (southern Chile)

2025-06-18

Pablo Fierro , Manuel Jesús López‐Rodríguez , José Manuel Tierno de Figueroa +1 more | Aquatic Insects

Considerations for using tag returns to monitor targeted removal of invasive fishes

2025-06-18

Jessica C. Stanton , Benjamin J. Marcek , Marybeth K. Brey | North American Journal of Fisheries Management

ABSTRACT Objective Targeted removals are used for management of some invasive fish populations. Tag–return studies are one approach that can be used to assess the efficacy of targeted removals. However, … ABSTRACT Objective Targeted removals are used for management of some invasive fish populations. Tag–return studies are one approach that can be used to assess the efficacy of targeted removals. However, there are many decisions to make when designing a tag–return study. We used simulation modeling to outline general guidelines for consideration when designing efficient tag–return studies to measure annual removal rates of invasive fish, particularly invasive carps. Methods We simulated data sets using scenarios with varying numbers of fish tagged per year, removal rates, tag reporting rates, tag retention rates, and study durations. We generated the data sets under a set of “known” parameters with added stochasticity; we then fitted the simulated data sets to a Bayesian tag–return model and measured the precision and accuracy of the model-estimated removal rates. Results We found that the model was able to predict removal rates without bias for most of the scenarios. However, we did find patterns in the precision of the predictions that could help to inform tag–return studies. When the proportion of the population removed through harvest was constant, the proportion of the population removed per year and the probability that harvested tags were reported had the largest effect on precision. The number of tags released per year and the study duration also had moderate effects. For scenarios testing the ability of the model to predict removal rates in stochastic populations, the precision of the model was primarily influenced by the number of fish tagged, the underlying nature of the stochasticity, and whether fish were tagged during the year of the prediction. Conclusions Based on our simulations, we outline how study objectives, the underlying population variability, and the tolerance range for error can guide decisions regarding the number of fish to tag, how to monitor tag return rates, and how long to conduct a study.

Passage performance of three small-sized fish species in a Vertical Slot Fishway with and without overhead cover

2025-06-18

Fabio Tarena , Claudio Comoglio , Michele Spairani +5 more | Ecological Engineering

Navigating Shallow Streams: Effects of Changing Stream Water Depths on Outmigration of Endangered Coho Salmon

2025-06-18

Brian Kastl , Mariska Obedzinski , Stephanie M. Carlson +7 more | River Research and Applications

ABSTRACT Declining streamflow from water management and climate change threatens fish migration. In coastal California, USA, we evaluated the effects of receding streamflow on the seaward migration of juvenile Coho … ABSTRACT Declining streamflow from water management and climate change threatens fish migration. In coastal California, USA, we evaluated the effects of receding streamflow on the seaward migration of juvenile Coho Salmon ( Oncorhynchus kisutch ) in four streams over 10 years (2010–2020). We monitored the movement of juveniles tagged with passive integrated transponders and measured depths at riffle crest thalwegs (RCTs), the shallowest channel feature that fish must navigate. Each stream exhibited a unique relationship between RCT depth and flow, relating to its geomorphic characteristics, producing distinct ranges of water depths among streams. During the peak migration period, juveniles moved over a wide range of depths (interquartile range 5.8–19.2 cm), with greater depths occurring in wet years than in dry years. However, the depths at which fish were detected were significantly deeper than continuous, observed depth measurements during the same period. We found the greatest differences between depth‐at‐movement and observed depths when streams were shallowest (< 10th percentile of observed depths). The timing at which stream depths fell below a regional fish passage criterion (9.1 cm) was also significantly correlated with the end of juvenile migration. In dry years, we observed greater variation in migration timing among streams, highlighting stream‐specific variation in the timing at which depths limit fish movement. Collectively, our study indicates that shallow depths impair salmon outmigration and that flow‐RCT depth relationships can be used to assess flow needs for fish migration and to guide streamflow restoration.

Using cumulative degree-days to refine sampling periods for early life stages of Lake Whitefish

2025-06-17

Steven A. Pothoven | North American Journal of Fisheries Management

ABSTRACT Objective Evaluating recruitment bottlenecks for Lake Whitefish Coregonus clupeaformis in the Great Lakes and inland lakes requires effective sampling of early life stages. The objective of this study was … ABSTRACT Objective Evaluating recruitment bottlenecks for Lake Whitefish Coregonus clupeaformis in the Great Lakes and inland lakes requires effective sampling of early life stages. The objective of this study was to determine whether targeted sampling of Lake Whitefish informed by a simple model relating total length to cumulative degree-days (CDDs; based on air temperature) could improve the precision of CPUE estimates by focusing sampling on specific sizes of larval and early juvenile fish. Methods Early life stages of Lake Whitefish were collected with neuston nets (larvae) or beach seines (juveniles) from southeast Lake Michigan during 2014–2022. Simple models were developed separately for larval and early juvenile Lake Whitefish to explain total length as a function of CDDs, day of year, or in situ water temperature. The CDD model was then used to determine when sampling should have occurred to target specific fish lengths for each life stage. Results Cumulative degree-days were the best predictor of fish total length for both larval fish in the neuston net (R2 = 0.71) and juvenile fish in the beach seine (R2 = 0.76). Restricting catches to the periods when fish lengths were in the target range resulted in a 29% and 26% lower average CV in CPUE for the neuston net and beach seine, respectively. Conclusions As climate change affects fish phenology, a simple model based on CDDs can focus sampling on specific fish lengths and improve precision of catch estimates for both larval and early juvenile Lake Whitefish with less overall sampling effort.

Assessing the cumulative effects of nearshore habitat restoration actions for multiple populations of juvenile salmon in Whidbey Basin, Washington: foundation and approach for synthesis and evaluation

2025-06-17

Kathryn L. Sobocinski , Michael T. LeMoine , Joshua Chamberlin +7 more | Frontiers in Marine Science

Ecosystem restoration is a common tool for re-establishing ecosystem processes, structures, and functions to improve biodiversity and services in coastal and estuarine ecosystems. In the Salish Sea, salmon habitats have … Ecosystem restoration is a common tool for re-establishing ecosystem processes, structures, and functions to improve biodiversity and services in coastal and estuarine ecosystems. In the Salish Sea, salmon habitats have been fragmented, reduced in size, and diminished in quality, and the ecosystem processes that form and sustain these habitats have been degraded and disrupted as well. This loss is especially prevalent in estuaries, where up to 90% of former salmon habitat has been lost or compromised. Salmon species are integral to the identities and cultures of people in the Pacific Northwest, yet salmon abundances remain at historic lows, especially in urbanized areas. Recent investments in restoration are creating rearing habitat and repairing lost ecosystem function. However, restoration efforts in this region have largely proceeded at the site scale, with less attention to big-picture thinking regarding how restoration will effectively recover degraded or lost habitats for target species. As a result, no landscape-scale evaluation program exists, and the cumulative benefits of multiple interventions are unknown. We describe innovative methods for science synthesis related to the evaluation of cumulative effects of ecosystem restoration for Pacific salmon, using years of existing, but disparate data. Building from previous work on cumulative effects evaluation and incorporating a hierarchy of hypotheses approach, we propose using causal inference across numerous hypotheses in a framework to assess the cumulative benefits to Pacific salmon from multiple estuarine restoration projects. We present the framework as a method that can be used to address many complex questions and provide examples from the Salish Sea where the approach is being implemented. The framework draws on science synthesis from numerous fields and uses a hierarchy of hypotheses, causal analysis at multiple scales, and a new hierarchy of synthesis for assessing multiple lines of evidence documenting restoration effects on Pacific salmon. We propose causal inference to synthesize dissimilar data streams, in our case, to identify various manifestations of cumulative effects of restoration and benefits to salmon, and to further inform restoration and recovery planning. A unifying framework would allow for the detection of thresholds at which restoration provides measurable improvement and would greatly advance understanding of the effects of restoration on ecosystems.

Distribution, community composition and vulnerability of fish species in the Algeti River Basin (Georgia)

2025-06-17

Giorgi Epitashvili , Giorgi Ramazashvili , Bella Japoshvili +1 more | Caucasiana

This study presents the first comprehensive survey of fish species’ diversity and distribution in the Algeti River and its reservoir in Georgia, a region within the Caucasus biodiversity hotspot. The … This study presents the first comprehensive survey of fish species’ diversity and distribution in the Algeti River and its reservoir in Georgia, a region within the Caucasus biodiversity hotspot. The research, conducted between 2016 and 2022, identified 19 fish species, including nine native to the Kura River basin and ten introduced or invasive species. The construction of a hydro power plant (HPP) dam in the 1980s and other subsequent anthropogenic activities have significantly altered the river ecosystem, creating distinct upstream, reservoir, and downstream sections with varying fish communities. The study reveals a concerning ongoing impact of anthropogenic factors on the Algeti River's fish fauna and whole ecosystem. The dam impedes fish migration; in addition, pollution, particularly in the mid-downstream section, has led to habitat degradation and a decline in native species. The introduction of non-native species, including predatory and bioturbator species, poses a substantial threat to the native fish populations. Our findings highlight the urgent need for conservation action to mitigate these threats. While the river's headwaters are within a protected area and some species are on the Red List of Georgia, alone these designations are insufficient safeguard. Effective conservation strategies must include stricter enforcement against illegal activities like poaching, as well as better pollution control and habitat management to preserve the Algeti River's biodiversity. This baseline study provides critical data for future research and conservation planning in this ecologically important region.

Revisiting Size Selective Morality in Young Fish: Do Small Teleosts Really Pay a Cost?

2025-06-17

Devon Robert Bath , Levi Newediuk | bioRxiv (Cold Spring Harbor Laboratory)

Small juvenile and larval teleosts are typically more susceptible to starvation and predation, so the largest individuals tend to survive. However, most support for this bigger is better hypothesis is … Small juvenile and larval teleosts are typically more susceptible to starvation and predation, so the largest individuals tend to survive. However, most support for this bigger is better hypothesis is experimental and does not account for the variation in food availability, competition, and other conditions that alter how starvation and predation affect small fish. To assess how natural populations experience size-selective mortality, we reviewed the past 30 years of literature on the subject while compiling 76 effect sizes of longitudinal survival data, which evaluates selection against size classes, to test for evidence that bigger is better. Our meta-analysis shows that the effect of body size on survival is consistently weak across species, populations, times, and locations. We discuss several reasons why larger young teleosts may not have a distinct survival advantage. We argue that they: 1) may be more profitable or noticeable to predators, 2) are unable to outgrow all their predators, and 3) require more resources, increasing their predator exposure out of necessity to forage. We recommend that mortality not be treated as constant across young teleost size classes, as different ecological conditions may favour smaller, larger, or neither size class. We suggest that the relationship between metabolic scope and mortality, geographic gradients in the importance of predation and starvation, and the interactive effects of alternative sources of mortality with predation and starvation in warming oceans are underexplored and could change how we think about the relationship between young teleost size and survival. Investigating these drivers will be important as temperatures rapidly rise, altering growth in wild fish.

Survival Estimates of Endangered Shortnose Sturgeon (Acipenser brevirostrum Lesueur, 1818) from Geographically Disjunct Population Segments

2025-06-17

Evan Ingram , Amanda Higgs , Liam Butler +2 more | Fishes

The complex life history and stock structure of endangered shortnose sturgeon (Acipenser brevirostrum) may hinder recovery efforts for individually managed river populations in the US. Reliable survival estimates are essential … The complex life history and stock structure of endangered shortnose sturgeon (Acipenser brevirostrum) may hinder recovery efforts for individually managed river populations in the US. Reliable survival estimates are essential for evaluating population trends and guiding conservation amid ongoing and emergent threats. However, such estimates are scarce in the recent literature and available for only a few wild populations, with their usefulness in practical management limited. In this study, we leverage multi-year acoustic telemetry data from monitoring projects in the Hudson River, New York (2012–2015), and Altamaha River, Georgia (2011–2014), to develop and compare survival estimates for spawning populations at opposite ends of the species’ US geographic range. Bayesian multistate capture–recapture models indicated high and precise apparent monthly adult survival in both the Hudson (0.991; 95% Bayesian credibility interval [CI]: 0.984–0.996) and Altamaha (0.980; 95% CI: 0.969–0.989) rivers, with implied annual survival rates of 0.897 and 0.787, respectively. Overall, this study advances our understanding of clinal variation in key demographic parameters and underscores the need to develop regionally specific goals for recovery. Broadening the estimates through increased telemetry coverage and integration of additional data will strengthen recovery efforts and support the long-term persistence of shortnose sturgeon across their range.

New insights into the collapse of Upper Lake Constance whitefish (Coregonus wartmanni) and the impact of commercial fisheries management

2025-06-17

Stefanie Haase , Jan Baer , Casper Willestofte Berg +4 more | Canadian Journal of Fisheries and Aquatic Sciences

The whitefish Coregonus wartmanni is the key fishery resource in Upper Lake Constance (ULC), one of Central Europe's largest lakes. A significant stock decline resulted in the closure of the … The whitefish Coregonus wartmanni is the key fishery resource in Upper Lake Constance (ULC), one of Central Europe's largest lakes. A significant stock decline resulted in the closure of the commercial whitefish fishery in 2024. Reasons for the decline have been contested, with suggestions ranging from environmental changes to overfishing. As in many inland fisheries, management in ULC previously lacked standardized protocols for stock assessment, and relied instead on technical measures like regulating mesh size and net numbers. To assess stock dynamics and estimate biomass and fishing mortality over the past 25 years (1997-2022), a surplus production model was applied using scientific gillnet surveys and commercial catch data. The results confirm that the whitefish stock is at a historically low level. Apparently, in 2012, when the stock already showed signs of overfishing, invasion of the pelagial by non-native stickleback (Gasterosteus aculeatus) triggered an ecosystem shift. Additional factors including oligotrophication, other invasive species and climate change also impact stock development, suggesting that reduced fishing pressure alone may not be enough to ensure short-term stock recovery.

Genetic Assessment of Floodplain Habitat Use by Juvenile Chinook Salmon

2025-06-16

Sara A. Hugentobler , J. Louise Conrad , Alisha Goodbla +2 more | San Francisco Estuary and Watershed Science

Climate change is having widespread negative effects on freshwater environments, including an increasing frequency and severity of droughts. Drought conditions present unique challenges for the federally listed Central Valley Chinook … Climate change is having widespread negative effects on freshwater environments, including an increasing frequency and severity of droughts. Drought conditions present unique challenges for the federally listed Central Valley Chinook Salmon (Oncorhynchus tshawytscha), which use the already limited floodplain in the Central Valley as rearing habitat. In this study, we examined how differing hydrologic conditions influence the run composition of juvenile Chinook Salmon in the floodplain (Yolo Bypass) vs. the mainstem of the Sacramento River. Juvenile Chinook Salmon from the Yolo Bypass and areas along the Sacramento River were identified to the genetically distinct runs (fall, late-fall, winter, and spring) from 2013 to 2019. We found overwhelmingly that length-at-date methods are misclassifying fish, particularly late-fall- and spring-run fish, and winter-run fish in the bypass. Using this genetic run-timing, we found that the abundances of endangered runs (spring and winter) are reduced during low flow periods in both the bypass and Sacramento River. Even during drought conditions, juvenile Chinook Salmon rearing in the Yolo Bypass attained significantly larger sizes than those in the Sacramento River. When comparing fish growth across time, during wet years fish in the bypass start smaller and get significantly larger over the course of the year, compared to drought years; while during both wet and dry years fish in the Sacramento River largely attain a smaller size than the Yolo Bypass fish. This suggests that floodplain habitat is critical to maintaining diversity in juvenile Chinook Salmon.

Predicting potential distributions of freshwater invasive species in novel environments

2025-06-16

Eric R. Larson | Freshwater Science

River Invertebrates Show That European Freshwater Habitats Have Stopped Improving

2025-06-16

James S. Sinclair , Peter Haase | Frontiers for Young Minds

Freshwater habitats have been harmed by pollution. People tried to fix this problem by reducing pollution from cities and farms, but we do not know if these efforts worked. To … Freshwater habitats have been harmed by pollution. People tried to fix this problem by reducing pollution from cities and farms, but we do not know if these efforts worked. To find out if they did, a group of scientists caught small animals, called invertebrates, from rivers across many European countries. Invertebrates can tell us if a river is polluted because we catch many different invertebrates in unpolluted rivers, but only a few in polluted rivers. If more invertebrates are caught each year, it means rivers are getting better. Researchers caught more invertebrates during the 1990s and 2000s. This was good news because it showed that reducing pollution helped many rivers. However, they did not catch more invertebrates in the 2010s. This means rivers stopped getting better, maybe because of other problems we have not fixed, like climate change. More work is therefore needed to help freshwater habitats improve again.

Seasonal Community Occupancy of Fishes in a Lowland (Arkansas, <scp>USA</scp>) Headwater Stream

2025-06-16

Tara L. Schnelting , Kyler B. Hecke | Ecology Of Freshwater Fish

ABSTRACT Among lowland fish communities, there is limited knowledge of the importance of headwaters. This information is needed to understand their role in fish communities. We addressed this gap by … ABSTRACT Among lowland fish communities, there is limited knowledge of the importance of headwaters. This information is needed to understand their role in fish communities. We addressed this gap by assessing seasonal changes in fish communities in lowland headwater streams (Arkansas, USA). 16 sites were sampled seasonally (winter, spring, summer and fall) in four events from Jan. to Oct. 2023. Multiple sampling gears (backpack electrofishing, kick nets and seines) were used to increase species detection. Fish presence/absence data, site and survey covariates were analysed using multiseason, community occupancy models to estimate μ , a value between 0 and 1, which represents the likelihood that an individual species is a member of the community and essentially represents that species occupancy (species probability), Ω , a value between 0 and 1, which represents the average occupancy probability across all species in the community across sites (community occupancy mean), and p , a value between 0 and 1, which is the probability of observing a species at a site given that the species is present (detection probability). A total of 37 species from 10 families were observed. Of the many models, we explored the best three: μ (canopy cover), Ω (canopy cover), p (.); μ (catchment area), Ω (catchment area), p (stream flow); μ (catchment area), Ω (catchment area) and p (.). The model incorporating canopy cover suggests that μ varied by species, Ω (± SE) varied by season and that p was constant. Overall, seasonal variation exists at the species and community levels; canopy cover and catchment area are the main drivers of μ and Ω and stream flow is the main driver of p . This research aids in the understanding of fish patterns and species richness on a temporal scale, improving knowledge of lowland headwater stream functionality in South Central Plains watersheds.

Contrasting responses to riverine barrier modification and fish pass provision in two anadromous non‐salmonid species during their spawning migrations

2025-06-16

Mark I. A. Yeldham , J. Robert Britton , Charles Crundwell +6 more | Journal of Applied Ecology

Abstract Anthropogenic in‐river structures represent barriers to migrating fishes. Fish pass designs usually focus on passing anadromous salmonids, and fish pass studies usually focus on site‐scale metrics, failing to consider … Abstract Anthropogenic in‐river structures represent barriers to migrating fishes. Fish pass designs usually focus on passing anadromous salmonids, and fish pass studies usually focus on site‐scale metrics, failing to consider the wider effects. Weir passage metrics and spawning distributions of anadromous iteroparous twaite shad Alosa fallax and semelparous sea lamprey Petromyzon marinus were assessed using acoustic telemetry between 2018 and 2023, within a catchment‐scale reconnection programme on the River Severn (‘Unlocking the Severn’ [UtS]). Reconnection was by fish pass installation (Severn mainstem; 3 deep‐vertical slot (DVS), 1 column bypass) and weir modification (Teme tributary; 1 partial removal/reduced head height, 1 reduced gradient). Time‐to‐event analysis revealed reconnection increased the probability of lamprey passing both the most downstream DVS and modified weir, and virgin shad were more likely than previous spawners to pass the DVS, but not the modified weir. Improvements in the proportion of tagged shad (to 7%) and lamprey (to 48%) passing the most downstream DVS were modest, but shad passage times were significantly reduced (by 20 days). Weir modification resulted in greater improvements in shad (to 58%) and lamprey (to 78%) passage. Reconnection also enabled passage on substantially lower flows; shad passed the most downstream Severn weir (via the DVS) at Q89 versus Q3 prior to construction, and lampreys at Q86 versus Q45. At catchment scales, reconnection significantly increased the proportion of shad passing the pre‐reconnection migration limit. However, the upstream extent of both species in the mainstem was not significantly increased. This was attributed to the limited motivations of individuals to access previously fragmented reaches; returning shad expressed fidelity to previous spawning sites and lamprey lacked pheromone cues from ammocoetes upstream. Passage motivations are predicted to increase subsequently as more individuals' spawn in these reaches. Synthesis and applications . UtS succeeded in facilitating both species to pass weirs under lower flow conditions than before. Weir modification improved passage rates more than fish pass installation, although catchment‐scale benefits currently remain limited. Project legacies include identifying long‐term monitoring needs to measure accumulating catchment‐scale benefits, and information on the suitability of reconnection methods to inform similar reconnection programmes.

Adapt or perish? Flexible habitat selection by an endangered and dispersal-limited fish under variable flow conditions and invasive crayfish competition

2025-06-16

Graciela Gómez Nicola , Daniel Ayllón , Ana Almodóvar +1 more | Hydrobiologia

Site fidelity during spawning period of a population of stocked fish

2025-06-16

Silviya V. Ivanova , Aaron T. Fisk , Timothy B. Johnson | Canadian Journal of Fisheries and Aquatic Sciences

Understanding site fidelity of a species provides insights into preferences and locations of key habitats associated with spawning, foraging, and other life-history events. For compromised species with high spawning site … Understanding site fidelity of a species provides insights into preferences and locations of key habitats associated with spawning, foraging, and other life-history events. For compromised species with high spawning site fidelity and where habitat quality impedes recruitment, insights into their behavioural variability may be useful for management. Here, we examined the relative intra-population variation in site fidelity for lake trout (Salvelinus namaycush) from eastern Lake Ontario during the spawning period, a population largely composed of stocked fish. Using a five-year dataset, we created an acoustic telemetry-specific site fidelity index. All tagged fish (n=72) returned to the general spawning area every year, but individuals showed varying fidelity to specific sites. Low fidelity was observed for 51.4% of individuals, compared to 27.8 and 20.8% showing medium and high, respectively. All females had low or medium fidelity compared to half of the males, demonstrating gender-based differences in fidelity. This study provides quantitative evidence that lake trout can display strong general spawning fidelity at larger (i.e., ecosystem) scales but moderate levels of behavioural variability and potential plasticity on smaller, regional scales (i.e., for specific sites) in freshwater ecosystems.

Transcriptional Differences in Gills Provide Insights into the Environmental Acclimatization of Wild Topmouth Gudgeon (Pseudorasbora parva) from Freshwater Invasion to Saline–Alkali Waters

2025-06-15

Lu Liu , Yongle Duan , Xuan Liu +4 more | Water

Topmouth Gudgeon (Pseudorasbora parva), a typical invasive fish worldwide, has successfully invaded various aquatic ecosystems and colonized saline–alkali waters from freshwater due to its broad environmental tolerances. However, the molecular … Topmouth Gudgeon (Pseudorasbora parva), a typical invasive fish worldwide, has successfully invaded various aquatic ecosystems and colonized saline–alkali waters from freshwater due to its broad environmental tolerances. However, the molecular mechanisms of adaptation to saline–alkali stress for P. parva remain poorly characterized. To explore the potential genetic mechanisms, we conducted differential gene expression analysis using gill transcriptome of wild P. parva populations collected from four waters with different salinity–alkalinity levels. Comparative transcriptomics analysis showed that DEGs involved in osmoregulation, ano6, cftr, aqp1, and aqp3, were down-regulated; DEGs related to ammonia excretion, Rhcg and Rhbg, were up-regulated; DEGs for acid–base accommodation, nhe2, slc4a1, and ca2, were down-regulated while ca4 was up-regulated; and immune-system-related DEGs, il8 and il17, were down- and up-regulated, respectively, in a high saline–alkaline water environment. The DEGs were enriched in multiple KEGG pathways, such as the ribosome, thermogenesis, oxidative phosphorylation, necroptosis, and HIF-1 signaling pathways. In addition, more DEGs were significantly enriched in immune-disease-related pathways in high saline–alkaline water populations. This suggests that P. parva exposed to chronic saline–alkali stress, despite survival, still needed immune system regulation to defend against potential diseases. These results revealed the gill molecular mechanisms underlying P. parva saline–alkaline adaptation and offered valuable insights into the development of saline–alkaline water aquaculture fisheries

Unraveling the genetic parameters, social relationships and conservation aspects of a group of Touit melanonotus (Brown-backed Parrotlet)

2025-06-15

Marina Vivianne Carcassola , Fernanda Bocalini , Luís Fábio Silveira +2 more | Ornithological Applications

Abstract The genetic parameters underlying the biological and behavioral traits of most Neotropical parrots are poorly understood due to limited sampling. Touit melanonotus (Brown-backed Parrotlet) is a globally Near Threatened, … Abstract The genetic parameters underlying the biological and behavioral traits of most Neotropical parrots are poorly understood due to limited sampling. Touit melanonotus (Brown-backed Parrotlet) is a globally Near Threatened, rare, unobtrusive, and small-bodied parrotlet endemic to the Atlantic Forest of Brazil. In 2020, a flock of T. melanonotus collided with a window at São Paulo International Airport in Guarulhos, São Paulo State, Brazil, resulting in the death of 29 individuals. We aimed to assess the genetic diversity of this flock, estimate the effective population size, and conduct a pairwise kinship analysis to explore flock formation, behavior, and the familial structure of this species. To that end, we used single nucleotide polymorphisms (SNPs) derived from genome-wide ultraconserved elements (UCEs) of the flock. We observed a higher-than-expected genetic diversity (t = 7.243, p ~ 0) and no evidence of inbreeding depression, with F ranging from –0.406 to –0.110 (χ2 = 37.687, p = 0; χ2 = 4.217, p = 0.040, respectively). We identified evidence of a historical decline in the effective population size of wild individuals, and kinship analysis indicated the presence of different familial nuclei, with multiple individuals pairing with more than one partner in the sampled group, which is a strong evidence for extra-pair copulation that may help maintain heterozygosity levels in this declining population. Based on our genetic parameters, we found no immediate or urgent need for genetic management as a conservation action. We recommend that conservation efforts focus on habitat maintenance and the restoration of the Atlantic Forest, a highly degraded and fragmented biome.

Analysis of the characteristics of the fish community structure and aquaculture capacity in the medium-sized reservoir—take the Qiaoying Reservoir as the case, China

2025-06-14

Xiaoyu Li , Yi Li , Bonian Shui +1 more | Environmental Monitoring and Assessment