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At least 1,189 records · Page 66Linked to original sources
USGS2016

Identifying alternate pathways for climate change to impact inland recreational fishers

Fisheries and human dimensions literature suggests that climate change influences inland recreational fishers in North America through three major pathways. The most widely recognized pathway suggests that climate change impacts habitat and fish populations (e.g., water temperature impacting fish survival) and cascades to impact fishers. Climate change also impacts recreational fishers by influencing environmental conditions that directly affect fishers (e.g., increased temperatures in northern climates resulting in extended open water fishing seasons and increased fishing effort). The final pathway occurs from climate change mitigation and adaptation efforts (e.g., refined energy policies result in higher fuel costs, making distant trips more expensive). To address limitations of past research (e.g., assessing climate change impacts for only one pathway at a time and not accounting for climate variability, extreme weather events, or heterogeneity among fishers), we encourage researchers to refocus their efforts to understand and document climate change impacts to inland fishers.

Fisheries↗
USGS2016

Biological and communication skills needed for introduced fish biologists

What skills and knowledge will a new graduate seeking employment need to work with introduced fishes? Clearly, success in introduced species management—similar to other disciplines in fisheries—requires a mixture of scientific and communication skills. However, specific abilities especially important to a biologist who manages introduced fishes should be highlighted. Unlike most other management strategies, stocking an introduced species can result in unintended and irreversible impacts, so particular care must be employed when stocking is considered. Furthermore, fish populations in areas outside of the introduced species management area might also be affected, usually negatively, if the introduced fish escapes. Therefore, rock-solid knowledge of basic aquatic ecology, including risk management; fish taxonomy (so the wrong fish species is not mistakenly stocked!); familiarity with human values of both the time and the place (which requires communication skills); and a strong understanding of human history are all important.

Fisheries↗
USGS2017

Fish Bioenergetics 4.0: An R-based modeling application

Bioenergetics modeling is a widely used tool in fisheries management and research. Although popular, currently available software (i.e., Fish Bioenergetics 3.0) has not been updated in over 20 years and is incompatible with newer operating systems (i.e., 64‐bit). Moreover, since the release of Fish Bioenergetics 3.0 in 1997, the number of published bioenergetics models has increased appreciably from 56 to 105 models representing 73 species. In this article, we provide an overview of Fish Bioenergetics 4.0 (FB4), a newly developed modeling application that consists of a graphical user interface (Shiny by RStudio) combined with a modeling package used in the R computing environment. While including the same capabilities as previous versions, Fish Bioenergetics 4.0 allows for timely updates and bug fixes and can be continuously improved based on feedback from users. In addition, users can add new or modified parameter sets for additional species and formulate and incorporate modifications such as habitat‐dependent functions (e.g., dissolved oxygen, salinity) that are not part of the default package. We hope that advances in the new modeling platform will attract a broad range of users while facilitating continued application of bioenergetics modeling to a wide spectrum of questions in fish biology, ecology, and management.

Fisheries Magazine↗
USGS2017

Synopsis of the Fourth International Percid Fishes Symposia

Percids play an integral role in food webs and freshwater fisheries of the world. Anthropogenic stressors such as pollution, overfishing, invasive species, and climate change threaten percid diversity and the sustainability of economically important fisher-ies. The International Percid Fish Symposium is the only scien-tific conference dedicated to this family of fishes, offering unique opportunities for communication, discussion, and collaboration among scientists studying these valuable fishes. In this synopsis, we review the history of the percid symposia with an emphasis on the recent Fourth International Percid Fish Symposium held in Tartu, Estonia, during April 2016 and discuss future needs and direction for this important scientific conference.

Fisheries↗
USGS2008

The impacts of mobile fishing gear on seafloor habitats in the Gulf of Maine (Northwest Atlantic): implications for conservation of fish populations

Fishing gear alters seafloor habitats, but the extent of these alterations, and their effects, have not been quantified extensively in the northwest Atlantic. Understanding the extent of these impacts, and their effects on populations of living marine resources, is needed to properly manage current and future levels of fishing effort and fishing power. For example, the entire U.S. side of the Gulf of Maine was impacted annually by mobile fishing gear between 1984 and 1990, based on calculations of area swept by trawl and dredge gear. Georges Bank was imparted three to nearly four times annually during the same period. Studies at three sites in the Gulf of Maine (off Swans Island, Jeffreys Bank, and Stellwagen Bank) showed that mobile fishing gear altered the physical structure (=complexity) of benthic habitats. Complexity was reduced by direct removal of biogenic (e.g., sponges, hydrozoans, bryozoans, amphipod tubes, holothurians, shell aggregates) and‐ sedimentary (e.g., sand waves, depressions) structures. Also, removal of organisms that create.structures (e.g., crabs, scallops) indirectly reduced complexity. Reductions in habitat complexity may lead to increased predation on juveniles of harvested species and ultimately recruitment to the harvestable stock. Because of a lack of reference sites, where use of mobile fishing is prohibited, no empirical studies have yet been conducted on a scale that could demonstrate population level effects of habitat‐management options. If marine fisheries management is to evolve toward an ecosystem or habitat management approach, experiments are required on the effects of habitat change, both anthropogenic and natural.

Maine↗
USGS2016

Evaluation of reproductive status in Atlantic Tripletail by traditional and nonlethal approaches

Reproductive biology information is an important tool for fishery management actions such as the identification of spawning areas and the development of protective size limits, bag limits, and seasons. Such information for the management of Atlantic Tripletail Lobotes surinamensis is currently limited, particularly in the western Atlantic Ocean, as information regarding the reproductive biology of this species is sparse in the published literature. To this end, we determined the reproductive status of tripletail and compared the results of a nonlethal sampling method, plasma vitellogenin (VTG) analysis, with those of two traditional (lethal) methods, gonadosomatic index (GSI) and gonad histology. A total of 223 (122 male and 101 female) tripletail were sampled over 2 years near Jekyll Island, Georgia. Gonad histology indicated that 107 (94%) of the male tripletail were in the spawning-capable reproductive phase. Female tripletail were found in all reproductive phases, but only nine (8.9%) were in the spawning-capable phase. Plasma VTG was strongly related to GSI in females ( R 2 = 0.832, n = 77), and female GSI differed significantly among reproductive phases ( p < 0.0001). The estimated length at which 50% (L50) of female tripletail reached maturity was 463 mm; however, the L50 for male tripletail could not be determined because of the lack of immature fish within the study sample. Our study provides valuable information for the management of tripletail and indicates that a nonlethal approach (plasma VTG) may be useful for differentiating developing and spawning-capable females from males and from females in other reproductive phases.

Georgia↗
USGS2020

Reservoir fish habitats: A perspective on coping with climate change

Climate change is the defining environmental problem for our generation. The effects of climate change are increasingly evident and are anticipated to profoundly affect our ability to conserve fish habitats and fish assemblages. Reservoirs are important structures for coping with projected shifts in water supply, but they also provide refuge for riverine fishes and retain distinct fish assemblages that support diverse fisheries. The effects of climate change on reservoirs are unique among aquatic systems because reservoirs have distinctive habitat characteristics due to their terrestrial origin and strong linkage to catchments. This article reviews (1) the projected effects of rising temperature and shifting precipitation on reservoir fish habitats, and (2) adaptation strategies to cope with the anticipated effects. Climate warming impacts to reservoirs may include higher water temperatures and shifts in hydrology that can result in reduced water levels in summer and fall, altered water residence cycles, disconnection from upstream riverine habitats and backwaters, increased stratification, eutrophication, anoxia, and a general shift in biotic assemblages including plants, invertebrates, and fishes. What is needed to adapt to these changes is a perspective that focuses on maintaining ecosystem functionality rather than on retaining a certain species composition. To that end, various strategies organized into planning, monitoring, and managing compartments are identified.

Reviews in Fisheries Science & Aquaculture↗
USGS2025

The National Fish Habitat Partnership – A unique path to conserving fish habitat

The National Fish Habitat Partnership (NFHP) is a science based, non-regulatory, partnership-driven effort to conserve fish habitat across the USA. The NFHP was developed in the early to mid-2000s in response to the noted declines to fish populations and their associated habitats across the USA with the effort led by the Association of Fish and Wildlife Agencies and supported by a wide range of federal and state fisheries agencies along with conservation organizations. Since 2006, 20 Fish Habitat Partnerships have been organized around specific habitats, fish species, or geographic areas. These partnerships have implemented 1,613 projects resulting in 9,720 habitat enhancements or parcels of habitat protected, including 7,962 riverine or coastline miles and 98,255 acres of marine, lake, impoundment, and reservoir fish habitat along with 1,499 science and data products using US$60,613,842 of direct NFHP investment matched or leveraged by $332,841,072. The NFHP was codified by the U.S. Congress in 2020 and reauthorized in 2024, building on the strong initial foundation and ensuring success into the future. Follow-up publications to this overview paper are planned by each Fish Habitat Partnership to fully describe the depth and breadth of this key U.S. habitat program.

Fisheries↗
USGS2025

Comparing surgery time and short-term incision healing for Largemouth Bass using smooth- and barbed-absorbable sutures

Objective Barbed sutures have become increasingly favored over traditional smooth sutures in human medicine but remain understudied in fisheries biotelemetry applications. Our objectives were to (1) compare surgery time and recovery time for Largemouth Bass Micropterus nigricans when using smooth- versus barbed-absorbable sutures to close the incisions and (2) compare the short-term healing rates of incisions that were closed with the two sutures. Methods We conducted a surgical trial using two incision closure methods: a smooth suture method, which used three interrupted sutures, and a barbed suture method, which used a running style suture. Surgery and surgical recovery times were recorded for each surgery. At 14 d postsurgery, each incision was scored for openness and inflammation. Results Barbed sutures (median surgery time = 133.5 s) resulted in higher surgical efficiency than smooth sutures (median surgery time = 255.0 s). Surgical recovery time did not differ between the two suture types. Mortality did not differ between suture types (overall mortality = 21%) and was similar to previously reported mortality rates. Incision site inflammation and openness were variable but did not differ between suture types. Conclusions Our results indicate that barbed sutures may increase surgical efficiency while maintaining currently observed survival and healing rates for Largemouth Bass.

North American Journal of Fisheries Management↗
USGS2025

Food habits of Yellow Perch, Smallmouth Bass, and Northern Pikeminnow in Lake Cascade, Idaho

Objective Yellow Perch Perca flavescens was first encountered in Lake Cascade, Idaho, in 1957. Since its introduction, the abundance of Yellow Perch in Lake Cascade has been highly variable. Historically, declines in Yellow Perch abundance were attributed to predation by Northern Pikeminnow Ptychocheilus oregonensis . In the 1990s, Smallmouth Bass Micropterus dolomieu became established in Lake Cascade. Although Yellow Perch abundance has been high and currently supports a world-class fishery, the Idaho Department of Fish and Game has documented poor Yellow Perch recruitment in recent years, concerning regional managers. An investigation into the food habits of Yellow Perch, Smallmouth Bass, and Northern Pikeminnow was conducted to better understand the importance of juvenile Yellow Perch to predator diets. Methods In Lake Cascade, gill nets were deployed monthly from April 2022 to May 2023. Ageing structures and stomach contents were removed from Yellow Perch, Smallmouth Bass, and Northern Pikeminnow. Diet composition was quantified and then summarized by species, cohort, and season. Bioenergetics modeling, coupled with estimates of predator abundance, was used to evaluate overall consumption of Yellow Perch. Results In total, stomach contents were extracted from 1,099 Yellow Perch, 440 Smallmouth Bass, and 980 Northern Pikeminnow. Food habits varied by season and predator length, but Yellow Perch was a primary prey item of all study species. The energetic contribution of Yellow Perch to Yellow Perch varied from 10% to 80% across seasons. Smallmouth Bass consumed fewer Yellow Perch than either Yellow Perch or Northern Pikeminnow. The highest average per capita consumption of Yellow Perch (i.e., across seasons) was observed for 500–600-mm Northern Pikeminnow (five Yellow Perch/Northern Pikeminnow). Energetic contribution of Yellow Perch to Northern Pikeminnow diets was highest in spring 2023, yet Northern Pikeminnow consumed the highest average number of Yellow Perch in July. Bioenergetics modeling estimated that per-capita annual consumption of Yellow Perch was 6.0 kg for Yellow Perch, 3.4 kg for Smallmouth Bass, and 9.9 kg for Northern Pikeminnow. In total, estimated consumption of all study species was as high as 37% of the estimated total number age-0 Yellow Perch produced. Conclusions Yellow Perch was an important prey item for all three species, particularly Yellow Perch and Northern Pikeminnow. Results from this study provide important information on the predation of Yellow Perch in Lake Cascade. Further, this work will bolster a growing body of research on the food habits of and interactions between native and nonnative predators in western reservoir systems.

Idaho↗
USGS2025

Estimating recruitment of Largemouth Bass to exceptional weights using angler-reported catches

ABSTRACT Objective Although most facets of Largemouth Bass Micropterus nigricans ecology have been researched, the upper tiers of weight distributions (i.e., ≥3.6 kg; herein, “lunkers”) have received little attention due to the challenges of collecting sufficient sample sizes. Our aim was to estimate Largemouth Bass recruitment to higher weights after reaching 3.6 kg and to identify factors correlated with such recruitment. Methods We used an online database of angler-reported catches to investigate recruitment of Largemouth Bass after reaching lunker size and to identify associated factors. Recruitment was indexed by the slopes of the reversed cumulative counts relative to increasing weights, with gentler negative slopes indicating higher recruitment. The influence of environmental variables on these slopes identified the factors associated with recruitment. Results An average of 20% (minimum = 4%; maximum = 45%) of lunker bass were estimated to recruit after reaching 3.6 kg. When expanded, these estimates revealed that recruitment from 3.6 to 4.5 kg averaged 23.5% and recruitment from 3.6 to 5.9 kg averaged 2.5%. The observed recruitment was positively correlated with the frequency of Florida Bass M. salmoides alleles in the population and was inversely correlated with human population densities in the vicinity of the reservoir and with chlorophyll- a concentrations in the environment. Conclusions Recruitment of Largemouth Bass after reaching 3.6 kg appears to require a nuanced equilibrium enabled by a higher frequency of Florida Bass alleles, a remote location of the fishery, and a reservoir trophic state that balances adequate environmental conditions and food supply.

North American Journal of Fisheries Management↗
USGS2025

Muskellunge spawning habitat characteristics and availability in Green Bay, Lake Michigan

Objective Habitat degradation has been associated with the loss of many self-sustaining Muskellunge Esox masquinongy populations, including those in Green Bay, where stocking has provided an exceptional trophy fishery but restoration goals include establishing self-sustaining populations and there is little evidence of natural recruitment. Our objectives were to determine whether (1) Muskellunge spawning locations and occurrence of successful hatching were related to a suite of habitat characteristics, (2) proportions of Muskellunge spawning in or outside of tributaries to lower Green Bay were different, and (3) Muskellunge showed spawning site fidelity. Methods From 2017 to 2019, adult Muskellunge ( N = 60) were surgically implanted with radio and acoustic transmitters to identify spawning locations, where we measured a suite of habitat variables and attempted to collect eggs and larvae. Side-scan sonar was used to quantify the amount of habitat available to Muskellunge for egg deposition in the Fox and Menominee rivers, which are tributaries to Green Bay. Results Muskellunge eggs were collected at 58 locations, but only two larvae were collected from a single location. Bottom slope, depth, distance to shore, gravel substrate, organic matter, and dissolved oxygen best predicted the presence of Muskellunge eggs. We determined that little habitat associated with Muskellunge egg deposition was available in the Fox and Menominee rivers. However, approximately half of tagged Muskellunge appeared to spawn outside of tributaries. Muskellunge in Green Bay displayed moderate spawning site fidelity. Conclusions Our results suggest that successful hatching occurs at very low levels and the lack of suitable Muskellunge spawning habitat in Green Bay tributaries may be limiting natural reproduction. Changes in spatial allocation of stocked fish and enhancement of known spawning locations may increase egg deposition and subsequent natural reproduction.

Michigan, Wisconsin↗
USGS2025

Hatchery rearing density affects poststocking survival

Objective Research has indicated that salmonids raised in a hatchery and stocked into the wild have lower future survival and reproductive success than wild fish. Understanding whether hatchery rearing practices affect populations after stocking can help to maximize the quality, quantity, and economic value of fish stocked for conservation and recreational purposes. The goal of our study was to test whether and to what extent rearing density affects poststocking survival of Rainbow Trout Oncorhynchus mykiss when stocked into a put-grow-and-take fishery. Methods Rainbow Trout were raised for 3 months in the hatchery at two densities (high = 51,948–13,072 fish/m 3 , rearing index 2.0, 1,260 metric units; low = 12,987–3,268 fish/m 3 , rearing index 0.5, 315 metric units). A subset of the fish were PIT-tagged and stocked into Parvin Lake, Red Feather Lakes, Colorado. Recaptures of tagged fish occurred every 2 weeks for the first 2 months poststocking and at 7 and 12 months poststocking. Results At the time of stocking, there were no statistical differences in Fulton’s condition factor, total length, weight, or hepatosomatic index for each treatment. Recapture data indicated that there was no difference in Fulton’s condition factor and hepatosomatic index after stocking. Apparent poststocking survival was higher for fish raised at low density in the hatchery compared with those raised at high density. Conclusions Our study suggests that rearing density affects fingerling Rainbow Trout poststocking survival. Stocking more fish due to fish being reared at higher densities within the hatchery did not result in more total fish remaining after a year in the lake compared with the low-density treatment. Rearing fish at high densities does not provide a benefit of more fish after stocking and may result in more disease risk in the hatchery.

Colorado↗
USGS2025

Revised length categories and standard weight equation for Northern Pikeminnow

Objective Length and weight indices (e.g., proportional size distribution, relative weight) provide standardized benchmarks that are useful for comparing groups of fish, identifying ecological interactions, and evaluating the effect of management actions. However, the current length categories and standard weight ( W s ) equation for Northern Pikeminnow Ptychocheilus oregonensis , a species of important management focus in the Pacific Northwest, were developed using limited data, unclear methods, and no validation. As such, we sought to revise the length categories and W s equation for Northern Pikeminnow. Methods We used the all-tackle world record to develop length categories for Northern Pikeminnow. We compiled data from 100,663 Northern Pikeminnow from 114 populations in Idaho, Montana, Oregon, Washington, and British Columbia to develop a revised W s equation. Most fish were measured in fork length (FL), so we converted total lengths (TLs) to FLs using the equation TL = −2.301 + 0.916(FL); r 2 = 0.998. We used the regression line percentile, linear empirical percentile (EmP), and quadratic EmP methods to develop 50th percentile and 75th percentile W s equations. We then assessed length-related biases in our W s equations and the previously published equation. Results We propose minimum FLs of 17 cm (7 inches; stock), 26 cm (10 inches; quality), 35 cm (14 inches; preferred), 41 cm (16 inches; memorable), and 51 cm (20 inches; trophy) for proportional size distribution calculations. The previously published W s equation exhibited substantial length-related biases according to the Willis and weighted empirical quartile method tests. The EmP 50th-percentile W s equation was the only equation that we evaluated that did not exhibit length-related bias. The EmP 50th-percentile W s equation was the best performing equation (i.e., no length-related bias detected). The equation is log 10 ( W s ) = −5.258 + 3.135(FL), where W s is in grams and FL is in millimeters. The equation is valid for Northern Pikeminnow 90–580 mm FL. Conclusion The length categories, length conversion, and W s equation presented here will aid fisheries professionals in the study and management of Northern Pikeminnow populations.

British Columbia, Idaho, Montana, Oregon Washingto↗
USGS2026

Gerrard strain Rainbow Trout are not piscivorous in a shallow, polymictic reservoir

Objective Georgetown Lake (Montana, USA) is renowned for its multispecies salmonid fishery. Although many anglers target kokanee Oncorhynchus nerka in Georgetown Lake, the body length of kokanee has typically been considered unsatisfactory. To reduce the density of kokanee and increase the average size, Montana Fish, Wildlife & Parks began stocking the piscivorous Gerrard strain of Rainbow Trout O. mykiss (hereafter “Gerrard”) in 2015 to consume kokanee. In 2020, preliminary evidence suggested that the average length of kokanee greater than 200 mm increased by almost 40 mm. Methods To assess the efficacy of biocontrol through the introduction of a piscivore to predate on kokanee, we examined the diet composition of all potential predators (three strains of Rainbow Trout and Brook Trout Salvelinus fontinalis ) to determine the amount of predation on kokanee and to understand the feeding ecology of all potential predators. Results There was little evidence of piscivory in any predator and no evidence of Gerrards consuming kokanee. Gerrards exhibited a generalist feeding strategy, and there was dietary overlap and no difference in trophic position among Gerrards and other predators. Conclusions From a biological-control perspective, there is no benefit in continuing to stock Gerrards to reduce kokanee densities in Georgetown Lake. These findings underscore the challenge of predicting predator–prey relationships, as diet plasticity can lead to unexpected dynamics based on resource availability and habitat structure within aquatic ecosystems, highlighting the importance of evaluating management interventions, such as biocontrols, in different ecosystems.

Montana↗
USGS2026

Egg thiamine concentrations reflect dietary differences between four hatchery strains, including two morphotypes, of Lake Trout in Lake Ontario

Objective Test whether dietary differences among hatchery strains of Lake Trout Salvelinus namaycush were associated with variation in egg thiamine concentrations and assess the potential for using strain-specific traits to mitigate thiamine deficiency complex (TDC) in Lake Ontario restoration efforts. Methods Stomach content analysis and stable isotope mixing models were used to compare diets among four hatchery strains of Lake Trout, representing lean and humper morphotypes. Egg thiamine concentrations were measured to test whether dietary differences correlated with susceptibility to TDC. Results Significant differences in diet and egg thiamine concentrations were observed among Lake Trout strains. A humper-like morphotype strain exhibited elevated thiamine levels, which were associated with reduced consumption of prey known to degrade thiamine levels when consumed, Alewife Alosa pseudoharengus and Rainbow Smelt Osmerus mordax , and increased reliance on Round Goby Neogobius melanostomus or sculpin species (Slimy Sculpin Cottus cognatus and Deepwater Sculpin Myoxocephalus thompsonii ). These findings support the link between the consumption of Alewife and Rainbow Smelt and thiamine deficiency. Conclusions Our findings support a link between strain-specific dietary preferences and susceptibility to TDC in Lake Trout. Preferential stocking of strains less prone to TDC, such as the strain derived from a humper morph from Lake Superior, could enhance restoration success in Lake Ontario. This strategy may be especially effective given the continued dominance of Alewife in the lake's prey base and the current management priorities supporting fisheries for Pacific salmon Oncorhynchus spp.

North American Journal of Fisheries Management↗
USGS2026

Beyond pro-vs-anti hatchery: A typology of fishing community perceptions of salmonid hatcheries in Oregon

Objectives: Pacific salmon and steelhead hatcheries are central to fisheries management along the West Coast of North America, yet they remain a source of persistent controversy. While often framed in binary terms of pro- or anti-hatchery, public perspectives are more nuanced. Methods: We conducted 18 in-depth interviews with members of Oregon’s non-tribal fishing communities, including recreational anglers, professional fishers, non-governmental organizations, hatchery workers, and policymakers, to explore perceptions of salmonid hatcheries. Results: We developed a typology of perceptions of salmonid hatcheries in Oregon, identifying five distinct belief-based types, which we label Advocates, Reformers, Balancers, Skeptics, and Restorers. These types differed in how they evaluated hatcheries’ social and ecological impacts, governance legitimacy, and management acceptability. While Advocates and Reformers emphasized hatcheries’ social, economic, cultural, and ecological benefits, Skeptics and Restorers prioritized minimizing ecological harm and questioned hatchery effectiveness. Balancers acknowledged both social benefits and ecological risks, supporting context-specific management. All groups articulated different meanings of the term “wild,” suggesting that different perspectives across typologies may exacerbate fundamental miscommunications. Conclusion: Our findings highlight the complexity of stakeholder views and the limitations of binary framings. We suggest that tailored communication and engagement strategies, informed by typologies, may foster more inclusive and productive dialogue in hatchery policy and management.

Oregon↗