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At least 613 records · Page 34Linked to original sources
USGS2025

The Center for the Advancement of Population Assessment Methodology (CAPAM): A perspective on the first 10 years

The Center for the Advancement of Population Assessment Methodology (CAPAM) was established in 2013, envisioned as an institute that could conduct, organize, and communicate stock assessment research with the aim of benefiting fisheries assessment efforts internationally. CAPAM’s activities have focused on its workshop series and consequent special issues in Fisheries Research . The information generated through CAPAM and its permanent recording as journal articles has greatly benefited the stock assessment community and can potentially contribute to modelling in general. We discuss what has made CAPAM successful, its future, and what could be done to reach the ultimate goal of producing a good practices guide for fisheries stock assessment.

Fisheries Research↗
USGS2003

US Atlantic coast striped bass: Issues with a recovered population

Striped bass, Morone saxatilis (Walbaum), is an anadromous species naturally occurring along the US Atlantic coast, which historically supported valuable commercial and recreational fisheries. In response to a near order-of-magnitude decline in landings, the Atlantic States Marine Fisheries Commission enacted a management plan in 1981 protecting fish until they could spawn at least once. By 1989, recruitment increased in natal rivers and regulations were relaxed, permitting limited fisheries by 1990. By 1995, the stock was declared fully recovered. Since the recovery, concern has increased over the health of the stocks. In the 1990s, fish in poor physical condition with dermal lesions became common in Chesapeake Bay. Pathogens of most concern in cultures from fish include the genus Mycobacterium. Coincident with declines in fish health were changes in diets, declines of preferred prey, and reduced growth and condition. Theories were suggested linking declines in condition to reductions in forage base or pathogens. Diets have changed since the 1950s and while many Chesapeake fish are infected with mycobacteria, it is still not known how or if these factors are linked. The highest priorities for research were considered to be: linking numerous local and regional studies to provide a coast-wide perspective; continuation of investigations linking population health to the prey-base; determination of the cause-effect of mycobacteria infections; and formulation of management options.

Fisheries Management and Ecology↗
USGS2011

Using a genetic mixture model to study phenotypic traits: Differential fecundity among Yukon river Chinook Salmon

Fecundity is a vital population characteristic that is directly linked to the productivity of fish populations. Historic data from Yukon River (Alaska) Chinook salmon Oncorhynchus tshawytscha suggest that length‐adjusted fecundity differs among populations within the drainage and either is temporally variable or has declined. Yukon River Chinook salmon have been harvested in large‐mesh gill‐net fisheries for decades, and a decline in fecundity was considered a potential evolutionary response to size‐selective exploitation. The implications for fishery conservation and management led us to further investigate the fecundity of Yukon River Chinook salmon populations. Matched observations of fecundity, length, and genotype were collected from a sample of adult females captured from the multipopulation spawning migration near the mouth of the Yukon River in 2008. These data were modeled by using a new mixture model, which was developed by extending the conditional maximum likelihood mixture model that is commonly used to estimate the composition of multipopulation mixtures based on genetic data. The new model facilitates maximum likelihood estimation of stock‐specific fecundity parameters without first using individual assignment to a putative population of origin, thus avoiding potential biases caused by assignment error. The hypothesis that fecundity of Chinook salmon has declined was not supported; this result implies that fecundity exhibits high interannual variability. However, length‐adjusted fecundity estimates decreased as migratory distance increased, and fecundity was more strongly dependent on fish size for populations spawning in the middle and upper portions of the drainage. These findings provide insights into potential constraints on reproductive investment imposed by long migrations and warrant consideration in fisheries management and conservation. The new mixture model extends the utility of genetic markers to new applications and can be easily adapted to study any observable trait or condition that may vary among populations.

Transactions of the American Fisheries Society↗
USGS2013

Assessing effects of stocked trout on nongame fish assemblages in southern Appalachian Mountain streams

Fisheries managers are faced with the challenge of balancing the management of recreational fisheries with that of conserving native species and preserving ecological integrity. The negative effects that nonnative trout species exert on native trout are well documented and include alteration of competitive interactions, habitat use, and production. However, the effects that nonnative trout may exert on nongame fish assemblages are poorly understood. Our objectives were to quantify the effects of trout stocking on native nongame fish assemblages intensively on one newly stocked river, the North Toe River, North Carolina, and extensively on other southern Appalachian Mountain streams that are annually stocked with trout. In the intensive study, we adopted a before-after, control-impact (BACI) experimental design to detect short-term effects on the nongame fish assemblage and found no significant differences in fish density, species richness, species diversity, or fish microhabitat use associated with trout stocking. We observed differences in fish microhabitat use between years, however, which suggests there is a response to environmental changes, such as the flow regime, which influence available habitat. In the extensive study, we sampled paired stocked and unstocked stream reaches to detect long-term effects from trout stocking; however, we detected no differences in nongame fish density, species richness, species diversity, or population size structure between paired sites. Our results revealed high inherent system variation caused by natural and anthropogenic factors that appear to overwhelm any acute or chronic effect of stocked trout. Furthermore, hatchery-reared trout may be poor competitors in a natural setting and exert a minimal or undetectable impact on native fish assemblages in these streams. These findings provide quantitative results necessary to assist agencies in strategic planning and decision making associated with trout fisheries, stream management, and conservation of native fishes.

Transactions of the American Fisheries Society↗
USGS2015

Landscape prediction and mapping of game fish biomass, an ecosystem service of Michigan rivers

The increased integration of ecosystem service concepts into natural resource management places renewed emphasis on prediction and mapping of fish biomass as a major provisioning service of rivers. The goals of this study were to predict and map patterns of fish biomass as a proxy for the availability of catchable fish for anglers in rivers and to identify the strongest landscape constraints on fish productivity. We examined hypotheses about fish responses to total phosphorus (TP), as TP is a growth-limiting nutrient known to cause increases (subsidy response) and/or decreases (stress response) in fish biomass depending on its concentration and the species being considered. Boosted regression trees were used to define nonlinear functions that predicted the standing crops of Brook Trout Salvelinus fontinalis , Brown Trout Salmo trutta , Smallmouth Bass Micropterus dolomieu , panfishes (seven centrarchid species), and Walleye Sander vitreus by using landscape and modeled local-scale predictors. Fitted models were highly significant and explained 22–56% of the variation in validation data sets. Nonlinear and threshold responses were apparent for numerous predictors, including TP concentration, which had significant effects on all except the Walleye fishery. Brook Trout and Smallmouth Bass exhibited both subsidy and stress responses, panfish biomass exhibited a subsidy response only, and Brown Trout exhibited a stress response. Maps of reach-specific standing crop predictions showed patterns of predicted fish biomass that corresponded to spatial patterns in catchment area, water temperature, land cover, and nutrient availability. Maps illustrated predictions of higher trout biomass in coldwater streams draining glacial till in northern Michigan, higher Smallmouth Bass and panfish biomasses in warmwater systems of southern Michigan, and high Walleye biomass in large main-stem rivers throughout the state. Our results allow fisheries managers to examine the biomass potential of streams, describe geographic patterns of fisheries, explore possible nutrient management targets, and identify habitats that are candidates for species management.

Michigan↗
USGS2015

Effectiveness of a refuge for Lake Trout in Western Lake Superior II: Simulation of future performance

Historically, Lake Superior supported one of the largest and most diverse Lake Trout Salvelinus namaycush fisheries in the Laurentian Great Lakes, but Lake Trout stocks collapsed due to excessive fishery exploitation and predation by Sea Lampreys Petromyzon marinus . Lake Trout stocking, Sea Lamprey control, and fishery regulations, including a refuge encompassing Gull Island Shoal (Apostle Islands region), were used to enable recovery of Lake Trout stocks that used this historically important spawning shoal. Our objective was to determine whether future sustainability of Lake Trout stocks will depend on the presence of the Gull Island Shoal Refuge. We constructed a stochastic age-structured simulation model to assess the effect of maintaining the refuge as a harvest management tool versus removing the refuge. In general, median abundances of age-4, age-4 and older (age-4+), and age-8+ fish collapsed at lower instantaneous fishing mortality rates ( F ) when the refuge was removed than when the refuge was maintained. With the refuge in place, the F that resulted in collapse depended on the rate of movement into and out of the refuge. Too many fish stayed in the refuge when movement was low (0–2%), and too many fish became vulnerable to fishing when movement was high (≥22%); thus, the refuge was more effective at intermediate rates of movement (10–11%). With the refuge in place, extinction did not occur at any simulated level of F , whereas refuge removal led to extinction at all combinations of commercial F and recreational F . Our results indicate that the Lake Trout population would be sustained by the refuge at all simulated F -values, whereas removal of the refuge would risk population collapse at much lower F (0.700–0.744). Therefore, the Gull Island Shoal Refuge is needed to sustain the Lake Trout population in eastern Wisconsin waters of Lake Superior.

Michigan, Minnesota, Wisconsin↗
USGS2016

Comparing life history characteristics of Lake Michigan’s naturalized and stocked Chinook Salmon

Lake Michigan supports popular fisheries for Chinook Salmon Oncorhynchus tshawytscha that have been sustained by stocking since the late 1960s. Natural recruitment of Chinook Salmon in Lake Michigan has increased in the past few decades and currently contributes more than 50% of Chinook Salmon recruits. We hypothesized that selective forces differ for naturalized populations born in the wild and hatchery populations, resulting in divergent life history characteristics with implications for Chinook Salmon population production and the Lake Michigan fishery. First, we conducted a historical analysis to determine if life history characteristics changed through time as the Chinook Salmon population became increasingly naturalized. Next, we conducted a 2-year field study of naturalized and hatchery stocked Chinook Salmon spawning populations to quantify differences in fecundity, egg size, timing of spawning, and size at maturity. In general, our results did not indicate significant life history divergence between naturalized and hatchery-stocked Chinook Salmon populations in Lake Michigan. Although historical changes in adult sex ratio were correlated with the proportion of naturalized individuals, changes in weight at maturity were better explained by density-dependent factors. The field study revealed no divergence in fecundity, timing of spawning, or size at maturity, and only small differences in egg size (hatchery > naturalized). For the near future, our results suggest that the limited life history differences observed between Chinook Salmon of naturalized and hatchery origin will not lead to large differences in characteristics important to the dynamics of the population or fishery.

Lake Michigan↗
USGS2014

Guidelines for use of fishes in research: Revised and expanded

The Guidelines for the Use of Fishes in Research (2014; 2014 Guidelines ), now available through the American fisheries Society (AFS) website and in print from the AFS bookstore, is a resource to aid researchers and regulatory authorities regarding responsible, scientifically valid research on fish and aquatic wildlife. The Guidelines for the Use of Fishes in Field Research (American Society of Ichthyologists and Herpetologists [ASIH] et al. 1987, 1988) emphasized field research and was followed by the 2004 Guidelines including laboratory research topics. Each version of the Guidelines has been jointly endorsed and/or published by the ASIH, the American Institute of Fishery Research Biologists (AIFRB), and AFS--each focusing on the scientific understanding, global conservation, and sustainability of aquatic animals, fisheries, and ecosystems. Changes with time necessitate revisions to make the Guidelines consistent with contemporary practices and scientific literature so to remain relevant as a technical resource. This document provides not only general principles relevant for field and laboratory research endeavors but includes specific requirements for researchers working within the United States and outside of the country. Within the scope of their expertise, the 2014 Uses of Fishers in Research (UFR) Committee members updated and revised sections, resulting in a 90-page 2014 Guidelines having undergone through peer review. As before, topical areas were addressed (see Table of Contents on page 416). Expanded coverage was provided on U.S. and international agencies and programs relevant to research with fishes. The Surgical Procedures and the Marking and Tagging section received special focus by a UFR Subcommittee. Feeds and Feeding and the Administration of Drugs, Biologics and Other Chemicals are just some of the newly added topics. The 2014 Guidelines is user-friendly by way of hyperlinks to external Internet sites, intradocument sections, and tables of acronyms with corresponding terms, low regulatory priority drugs, and Office of International des Epizooties notifiable disease agents. Again, the Institutional Animal Care and Use Committee (IACUC) role is explained, expectations for research are provided, and a brief checklist for IACUC readiness is included. Overall, the ,i>2014 Guidelines is the taxon-specific resource for our professional societies and is a principal document for standards on the care and use of fish and aquatic vertebrates in research.

Fisheries↗
USGS2016

Who Knew? Inconnu

In 1999, I moved to Alaska to serve as unit leader of the U.S. Geological Survey Alaska Cooperative Fish and Wildlife Research Unit and professor of fisheries in the School of Fisheries and Ocean Sciences at the University of Alaska Fairbanks. What was unusual about this move was that before this I was an easterner and southerner, having done my graduate work in fisheries at Texas A&M University and been stationed in the Coop Unit Program in Ohio, West Virginia, and Maryland. I had never worked with salmonids of any sort. To me fish with adipose fins also had whiskers! I suddenly found myself working in the land of salmon experts, and I didn't even reliably know the names—scientific, common, or colloquial—of the five (or is it six?) common Pacific salmon species in Alaska. I had to quickly find a research niche that probably didn't involve salmon.

Fisheries↗
USGS2016

Stakeholder views of management and decision support tools to integrate climate change into Great Lakes Lake Whitefish management

Decision support tools can aid decision making by systematically incorporating information, accounting for uncertainties, and facilitating evaluation between alternatives. Without user buy-in, however, decision support tools can fail to influence decision-making processes. We surveyed fishery researchers, managers, and fishers affiliated with the Lake Whitefish Coregonus clupeaformis fishery in the 1836 Treaty Waters of Lakes Huron, Michigan, and Superior to assess opinions of current and future management needs to identify barriers to, and opportunities for, developing a decision support tool based on Lake Whitefish recruitment projections with climate change. Approximately 64% of 39 respondents were satisfied with current management, and nearly 85% agreed that science was well integrated into management programs. Though decision support tools can facilitate science integration into management, respondents suggest that they face significant implementation barriers, including lack of political will to change management and perceived uncertainty in decision support outputs. Recommendations from this survey can inform development of decision support tools for fishery management in the Great Lakes and other regions.

Fisheries↗
USGS2017

Future of Pacific salmon in the face of environmental change: Lessons from one of the world's remaining productive salmon regions

Pacific salmon Oncorhynchus spp. face serious challenges from climate and landscape change, particularly in the southern portion of their native range. Conversely, climate warming appears to be allowing salmon to expand northwards into the Arctic. Between these geographic extremes, in the Gulf of Alaska region, salmon are at historically high abundances but face an uncertain future due to rapid environmental change. We examined changes in climate, hydrology, land cover, salmon populations, and fisheries over the past 30–70 years in this region. We focused on the Kenai River, which supports world-famous fisheries but where Chinook Salmon O. tshawytscha populations have declined, raising concerns about their future resilience. The region is warming and experiencing drier summers and wetter autumns. The landscape is also changing, with melting glaciers, wetland loss, wildfires, and human development. This environmental transformation will likely harm some salmon populations while benefiting others. Lowland salmon streams are especially vulnerable, but retreating glaciers may allow production gains in other streams. Some fishing communities harvest a diverse portfolio of fluctuating resources, whereas others have specialized over time, potentially limiting their resilience. Maintaining diverse habitats and salmon runs may allow ecosystems and fisheries to continue to thrive amidst these changes.

Alaska↗
USGS2025

On the importance and practical conservation of nongame fishes.

Fisheries management has historically focused conservation efforts on game or sport species. However, most species are nongame—those not traditionally captured for sport or harvest in countries where recreational fisheries predominate. Greater conservation of nongame species could help ensure that population declines do not go unnoticed. Unfortunately, fisheries managers already manage complex ecosystems with limited resources, and they frequently are directed to focus on game fishes. However, game fish populations can also be tightly coupled to nongame fishes, so nongame management can sometimes also benefit game species. We reviewed functional roles of freshwater nongame fishes and suggest categories that may be especially important for conservation. Of note, nongame fishes are more imperiled than game fishes and fill largely distinct functional roles. These roles include food-web impacts, ecosystem engineering, and mussel hosting. Management priorities could include nongame piscivores and species with high biomass, especially herbivores, nest builders, and imperiled mussel hosts. We provide practical options for including nongame fishes in current management, many of which require little additional funding. These include recognizing when sport fish funding and conservation can also benefit nongame species, whole-community sampling at some monitoring locations, collecting catch data for select species observed during game fish surveys, embracing environmental DNA sampling, and making presence–absence record keeping the default option.

Fisheries↗
USGS2025

Recovery of Delaware Bay horseshoe crabs following harvest reductions

Objective Horseshoe crabs Limulus polyphemus play a vital role in the Delaware Bay ecosystem. The migratory stopover of several shorebird species occurs during the horseshoe crab spawning season, and the eggs of horseshoe crabs provide an essential food source to fuel their northward migration to breeding areas. High commercial fishery use of horseshoe crabs as bait during the 1990s coincided with a decline in crabs and shorebirds, particularly the red knot Calidris canutus rufa , which has been listed as threatened under the U.S. Endangered Species Act since 2015. In response to the population decline of shorebirds, the Atlantic States Marine Fisheries Commission began reducing the harvest of horseshoe crabs in 2000 with a goal of rebuilding the population of horseshoe crabs and shorebirds that depend upon them. The objective of this analysis was to determine whether horseshoe crab harvest management in the Delaware Bay region has increased the abundance of the species in recent years. Methods We analyzed data from fisheries-independent trawl surveys of horseshoe crab relative abundance using a Bayesian hierarchical model to determine whether harvest management has resulted in the rebuilding of the horseshoe crab population to levels seen in 1990—a period before the overuse of horseshoe crabs and the decline in the population of red knots. Results Data from multiple surveys showed that the horseshoe crab population in Delaware Bay declined from the 1990s through approximately 2005, was relatively low and stable until 2010, and then increased through 2023, with a 0.38 probability of exceeding the 1990 level. Conclusions The results of this analysis support the effectiveness of management decisions related to horseshoe crabs in the Delaware Bay region. In response to harvest restrictions, the abundance of horseshoe crabs has neared levels observed in the early 1990s—a period prior to high commercial use and a decline in both horseshoe crabs and shorebirds that depend on them for food during annual migrations.

Delaware, Maryland, New Jersey↗
USGS2025

Estimating mortality of Lake Sturgeon in the Lake Winnebago system using traditional age-based approaches and capture–recapture models

Objective The Lake Winnebago system in Wisconsin supports a popular winter spear fishery for Lake Sturgeon Acipenser fulvescens . Setting harvest caps for this fishery relies on estimating instantaneous natural mortality rate ( M ), which can be done using age-based approaches or capture–recapture models that incorporate recoveries of fish with passive integrated transponder (PIT) tags or detections of fish with acoustic transmitters. Our objectives were to determine (1) if recent estimates of exploitation ( u ) have exceeded the 5% harvest cap, (2) if M and total mortality rates are similar among estimation methods that rely on age estimates or capture–recapture methods, and (3) if potential differences in mortality estimates would affect harvest caps. Methods Harvest of PIT-tagged fish was used to evaluate u from 2010 to 2019. Catch curves incorporating corrected fin ray ages were used to estimate total mortality and M for fish collected from 2010 to 2019. Capture–recapture models were used to estimate annual survival and M from detections of fish with acoustic transmitters from 2007 to 2019 and recoveries of PIT-tagged fish from 1999 to 2020. Mortality estimates were used to calculate and compare sex-specific harvest caps among estimation methods. Results Observed u did not exceed 5% for either sex between 2010 and 2019. Estimates of M varied among methods (males: M = 0.001–0.134; females: M = 0.001–0.131), with PIT-based models consistently providing the lowest and telemetry-based models providing the highest estimates. Simulations indicated that female u has limited potential to exceed 5% if M from fin ray ages or telemetry is used to set harvest caps, while PIT-based simulations showed no indication of cap exceedance. Conclusions Harvest management practices in the Lake Winnebago system appear to have kept Lake Sturgeon exploitation below the 5% harvest cap from 2010 to 2019. Capture–recapture models relying on PIT tags appear to provide the most precise approach for setting harvest caps for this fishery.

Wisconsin↗
USGS2019

Biogeographic freshwater fish pattern legacy revealed despite rapid socio-economic changes in China

Understanding drivers of freshwater fish assemblages is critically important for biodiversity conservation strategies, especially in rapidly developing countries, which often have environmental protections lagging behind economic development. The influences of natural and human factors in structuring fish assemblages and their relative contributions are likely to change given the increasing magnitude of human activities. To discriminate natural and human drivers of fish diversity and assemblage patterns in developing countries with rapid socio-economic development, a dataset of 908 freshwater fish species and 13 metrics including three categories of both natural (i.e., biogeographic) and human drivers (i.e., economic growth, inland fisheries) in China were analysed with machine learning algorithms (i.e., self-organizing map, random forest). Here, we found that biogeographic drivers explained 21.8% of the observed fish assemblage patterns in China and remained stronger predictors when compared to human drivers (i.e., 15.6%, respectively). Freshwater fish species richness was positively correlated to rainfall, air temperature, surface water area and inland fisheries production but negatively correlated with urbanization. In addition, the strong structuring effects of climatic variables on Chinese fish richness patterns suggested that the fish assemblages could be particularly vulnerable to climate change. Our results showed that natural biogeographic factors still dominate in driving freshwater fish assemblage patterns despite increased human disturbances on aquatic ecosystems in a rapidly developing country. These findings consequently suggested that we should consider both natural (e.g., climate) and human (e.g., urbanization, inland fisheries) factors when establishing aquatic conservation strategies and priorities for developing countries that are experiencing rapid socio-economic changes.

Fish and Fisheries↗
USGS2021

Integrating seabird dietary and groundfish stock assessment data: Can puffins predict pollock spawning stock biomass in the North Pacific?

Information on the annual variability in abundance and growth of juvenile groundfish can be useful for predicting fisheries stocks, but is often poorly known owing to difficulties in sampling fish in their first year of life. In the Western Gulf of Alaska (WGoA) and Eastern Bering Sea (EBS) ecosystems, three species of puffin (tufted and horned puffin, Fratercula cirrhata, Fratercula corniculata, and rhinoceros auklet , Cerorhinca monocerata , Alcidae), regularly prey upon (i.e., “sample”) age-0 groundfish, including walleye pollock ( Gadus chalcogramma , Gadidae) and Pacific cod ( Gadus microcephalus , Gadidae). Here, we test the hypothesis that integrating puffin dietary data with walleye pollock stock assessment data provides information useful for fisheries management, including indices of interannual variation in age-0 abundance and growth. To test this hypothesis, we conducted cross-correlation and regression analyses of puffin-based indices and spawning stock biomass (SSB) for the WGoA and EBS walleye pollock stocks. For the WGoA, SSB leads the abundance of age-0 fish in the puffin diet, indicating that puffins sample the downstream production of the WGoA spawning stock. By contrast, the abundance and growth of age-0 fish sampled by puffins lead SSB for the EBS stock by 1–3 years, indicating that the puffin diet proxies incoming year class strength for this stock. Our study indicates connectivity between the WGoA and EBS walleye pollock stocks. Integration of non-traditional data sources, such as seabird diet data, with stock assessment data appears useful to inform information gaps important for managing US fisheries in the North Pacific.

Alaska↗
USGS2016

Prey size and availability limits maximum size of rainbow trout in a large tailwater: insights from a drift-foraging bioenergetics model

The cold and clear water conditions present below many large dams create ideal conditions for the development of economically important salmonid fisheries. Many of these tailwater fisheries have experienced declines in the abundance and condition of large trout species, yet the causes of these declines remain uncertain. Here, we develop, assess, and apply a drift-foraging bioenergetics model to identify the factors limiting rainbow trout (Oncorhynchus mykiss) growth in a large tailwater. We explored the relative importance of temperature, prey quantity, and prey size by constructing scenarios where these variables, both singly and in combination, were altered. Predicted growth matched empirical mass-at-age estimates, particularly for younger ages, demonstrating that the model accurately describes how current temperature and prey conditions interact to determine rainbow trout growth. Modeling scenarios that artificially inflated prey size and abundance demonstrate that rainbow trout growth is limited by the scarcity of large prey items and overall prey availability. For example, shifting 10% of the prey biomass to the 13 mm (large) length class, without increasing overall prey biomass, increased lifetime maximum mass of rainbow trout by 88%. Additionally, warmer temperatures resulted in lower predicted growth at current and lower levels of prey availability; however, growth was similar across all temperatures at higher levels of prey availability. Climate change will likely alter flow and temperature regimes in large rivers with corresponding changes to invertebrate prey resources used by fish. Broader application of drift-foraging bioenergetics models to build a mechanistic understanding of how changes to habitat conditions and prey resources affect growth of salmonids will benefit management of tailwater fisheries.

Arizona↗
USGS2018

Bipartite networks improve understanding of effects of waterbody size and angling method on angler–fish interactions

Networks used to study interactions could provide insights to fisheries. We compiled data from 27 297 interviews of anglers across waterbodies that ranged in size from 1 to 12 113 ha. Catch rates of fish species among anglers grouped by species targeted generally differed between angling methods (bank or boat). We constructed angler–catch bipartite networks (angling method specific) between anglers and fish and measured several network metrics. There was considerable variation in networks among waterbodies, with multiple metrics influenced by waterbody size. Number of species-targeting angler groups and number of fish species caught increased with increasing waterbody size. Mean number of links for species-targeting angler groups and fish species caught also increased with waterbody size. Connectance (realized proportion of possible links) of angler–catch interaction networks decreased slower for boat anglers than for bank anglers with increasing waterbody size. Network specialization (deviation of number of interactions from expected) was not significantly related to waterbody size or angling methods. Application of bipartite networks in fishery science requires careful interpretation of outputs, especially considering the numerous confounding factors prevalent in recreational fisheries.

Canadian Journal of Fisheries and Aquatic Sciences↗