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USGS2020

Inexpensive, underwater filming of rare fishes in high definition

Generating public interest in fish and their biology is often challenging. Many aquatic species are cryptic and largely invisible to the public. Therefore, increasing public awareness of cryptic fishes and elevating their visibility to broad audiences requires innovation. Inexpensive technological advancements now provide fisheries biologists, managers, and researchers with means never before possible for documenting fish in their natural habitat via underwater videography. We investigated cost efficient and simple methods for capturing and creating high quality, high definition, and informative underwater videos that could be used by people with little or no previous experience in videography. We tested 1) a variety of filming equipment including cameras and camera recording settings, lenses, batteries, and memory cards; 2) active and passive camera deployment techniques; and 3) a variety of free and paid postproduction software and compared them for ease of use, expense, and quality of output. Highest quality footage, i.e., highest resolution, clearest, and most stable, was obtained using a GoPro action camera deployed underwater in a stationary position mounted to a metal base plate using a combination of stock and macro lenses, and filming in 4K resolution at 30 frames per second. Final production videos were created using Adobe Premiere Pro.

Fisheries Magazine↗
USGS2021

Does type, quantity, and location of habitat matter for fish diversity in a Great Plains riverscape?

Fisheries professionals frequently measure habitat type and amount, but less often measure the importance of where those habitats are located and in what combinations. We address this challenge by testing whether the individual and combined type, quantity, and location of habitat affects fish diversity in the upper Neosho River basin, Kansas, as a different approach to measuring habitat heterogeneity. Habitat type mattered in that species richness increased in areas of higher riffle density. Furthermore, variation within habitat type also influenced fish diversity; specifically, slower, shallower riffles had more species of fish. The spatial arrangement (i.e., impact of neighbor habitats) influenced fish diversity patterns in that riffle–run and riffle–glide pairings altered riffle habitat characteristics. The study illustrates a useful approach by measuring the type, amount, and arrangement of habitats to assess fish populations and could be adapted to other stream ecosystems.

Kansas↗
USGS2021

The U.S. Inland Creel and Angler Survey Catalog (CreelCat): Development, applications, and opportunities

Inland recreational fishing, defined as primarily leisure-driven fishing in freshwaters, is a popular pastime in the USA. State natural resource agencies endeavor to provide high-quality and sustainable fishing opportunities for anglers. Managers often use creel and other angler survey data to inform state- and waterbody-level management efforts. Despite the broad implementation of angler surveys and their importance to fisheries management at state scales, regional and national coordination among these activities is minimal, limiting data applicability for larger-scale management practices and research. Here, we introduce the U.S. Inland Creel and Angler Survey Catalog (CreelCat), a first-of-its-kind, publicly available national database of angler survey data that establishes a baseline of national inland recreational fishing metrics. We highlight research and management applications to help support sustainable inland recreational fishing practices, consider cautions, and make recommendations for implementation.

Fisheries Magazine↗
USGS2022

Premature mortality observations among Alaska’s Pacific salmon during record heat and drought in 2019

Widespread mortality of Pacific salmon Oncorhynchus spp. returning to spawn in Alaska coincided with record-breaking air temperatures and prolonged drought in summer 2019. Extreme environmental conditions are expected to happen more frequently with rapid climate change and challenge the notion that Alaska could indefinitely provide abundant, cool freshwater habitat for Pacific salmon. A total of 110 geographically widespread opportunistic observations of premature mortality (carcasses) were collected from a variety of sources. Premature mortalities were documented for Pink Salmon Oncorhynchus gorbuscha , Sockeye Salmon O. nerka , Chum Salmon O. keta , Chinook Salmon O. tshawytscha , and Coho Salmon O. kisutch . Additionally, observations of Pink Salmon returning to spawn in Prince William Sound streams in 2019, obtained from systematic aerial surveys conducted annually, revealed low migration success in 87% of rain-driven streams ( n = 30), 52% of snow-driven streams ( n = 65), and only 18% of glacier-driven streams ( n = 11). Salmon mortality observations were consistent with death due to heat stress resulting from high water temperatures or drought caused hypoxia and stranding. Developing a better understanding of how broad-scale climate patterns manifest at the stream scale can help us determine whether a major shift in Pacific salmon productivity is underway and inform fisheries management plans to better mitigate future risks.

Alaska↗
USGS2023

Synthesizing professional opinion and published science to build a conceptual model of Walleye recruitment

Understanding and predicting recruitment, longstanding goals in fisheries science and ecology, are complicated by variation in the importance of environmental drivers coupled with the dynamic nature of individual ecosystems. Developing an understanding of recruitment from well-monitored stocks offers an opportunity to overcome these complexities. We used a systematic literature review, a survey, and a workshop attended by professionals with expertise in recruitment of Walleye Sander vitreus to identify common environmental drivers of Walleye recruitment and additional sources of variation (i.e., context dependencies) among populations. The importance of individual environmental drivers, as well as the direction of their influence, differed as a function of geographic region, lake surface area, and Walleye life stage. The literature suggested abiotic conditions (e.g., temperature) during the first year of life were influential in determining recruitment. Professional opinion noted the importance of biotic factors, with prey availability and predation risk having the most consistent relationships with recruitment. We synthesized this information to propose a conceptual model that illustrates the suite of characteristics that shape Walleye recruitment over large spatial and temporal scales. Our findings emphasize the importance of first-year growth and system-specific contextual factors, which can alter the relative importance of the environmental drivers of recruitment.

Fisheries Magazine↗
USGS2023

Kings of the North: Bridging disciplines to understand the effects of changing climate on Chinook salmon in the Arctic-Yukon-Kuskokwim Region

Understanding how species are responding to environmental change is a central challenge for stewards and managers of fish and wildlife who seek to maintain harvest opportunities for communities and Indigenous peoples. This is a particularly daunting but increasingly important task in remote, high-latitude regions where environmental conditions are changing rapidly and data collection is logistically difficult. The Arctic-Yukon-Kuskokwim (AYK) region encompasses the northern extent of the Chinook Salmon Oncorhynchus tshawytscha range where populations are experiencing rapid rates of environmental change across both freshwater and marine habitats due to global climate change. Climate–salmon interactions in the AYK region are a particularly pressing issue as many local communities have a deep reliance on a subsistence way of life. Here, we synthesize perspectives shared at a recent workshop on Chinook Salmon declines in the AYK region. The objectives were to discuss current understandings of climate-Chinook Salmon interactions, develop a set of outstanding questions, review available data and its limitations in addressing these questions, and describe the perspectives expressed by participants in this workshop from diverse backgrounds. We conclude by suggesting pathways forward to integrate different types of information and build relationships among communities, academic partners, and fishery management agencies.

Alaska, British Columbia, Yukon↗
USGS2023

Forage fish species prefer habitat within designated offshore wind energy areas on the US Northeast Shelf ecosystem

As the world develops sources of renewable energy, there is an intensifying interest in offshore wind energy production. The Northeast U.S. Continental Shelf (NES) ecosystem has favorable wind dynamics, with active development of wind energy. In this study, we present species distribution models that consider both occupancy and biomass responses for a broad spectrum of fish and macroinvertebrate taxa ( n = 177). Building upon prior analyses, habitat was differentiated into overall and core habitats based on statistical distributions of habitat scores. Overall habitat was used to show each species' regional distribution based on fishery-independent survey captures between 1976 and 2019, whereas core habitat represented where the focus of the species' abundance was located as a subset of overall habitat. Wind energy developments may modify the water column in ways that impact lower-trophic-level productivity; therefore, added attention was given to the response of forage species. Over 20% of species showed preferential use of putative and potential wind development areas, including a disproportionate number of forage taxa. Principal usage varied by season, with forage species like Atlantic Menhaden Brevoortia tyrannus and Atlantic Mackerel Scomber scombrus preferentially using the lease areas in spring and Round Herring Etrumeus teres and longfin inshore squid Doryteuthis pealeii using lease areas in autumn. For species with relatively low usage of the lease areas, there was a tendency for the usage related to overall habitat to be lower than usage for core habitat; in contrast, for species with high usage of the lease areas, that usage was higher for overall habitat than for core habitat. The area of habitat tended to have positive trends across species, with these positive trends being disproportionately higher among forage taxa. These results frame the importance of wind lease areas for species in the NES, particularly forage taxa that fulfill many important ecological functions.

Marine and Coastal Fisheries: Dynamics, Management↗
USGS2024

The use of conceptual ecological models to identify critical data and uncertainties to support numerical modeling: The northern Gulf of Mexico eastern oyster Crassostrea virginica example

Objective Increasing reliance on numerical simulation models to help inform management and restoration choices benefits from careful consideration of critical early steps in model development. Along the northern coast of the Gulf of Mexico, the eastern oyster Crassostrea virginica fulfills important ecological and economic roles. Using the eastern oyster as an example, we draw on several recent frameworks outlining best practices for model development and application for restoration, conservation, and management. Methods We identify priority model questions, outline a conceptual ecological model (CEM) to guide numerical model development, and use this framework to identify uncertainties and research needs. Result The CEM uses a nested design, identifying explicit vital rates, processes, attributes, and outcomes for the species (oysters), population, and metapopulation (i.e., network of populations) levels in response to drivers of species, population, and metapopulation changes and changing environmental factors. Most management actions related to oyster restoration and harvest affect population attributes directly, but many coastal management actions and changes (i.e., climate change and coastal and water resource engineering) impact environmental factors that alter vital rates and attributes of oysters, populations, and metapopulations. Conclusion Investment in studies targeting individual oyster‐ and population‐level multi‐stressor responses (filtration, respiration, growth, and reproduction) and improving hydrodynamic and environmental models targeting drivers that influence metapopulation vital rates and attributes (i.e., connectivity and substrate persistence) would contribute to reducing uncertainties. Development of numerical models covering the entire oyster life cycle and connectivity of populations using hydrodynamic models of current and predicted conditions to provide key abiotic and biotic factors influencing larval movement, recruitment, and on‐reef oyster vital rates would assist in balancing the goals of conservation, restoration, and fisheries management of this foundational estuarine species.

Marine and Coastal Fisheries: Dynamics, Management↗
USGS2018

Effects of summer air exposure on the survival of caught-and-released salmonids

Despite the success of catch‐and‐release regulations, exposing fish to air during release has emerged as a growing concern over the past two decades. We evaluated the effect of air exposure during midsummer on survival of Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri , Bull Trout Salvelinus confluentus , and Rainbow Trout O. mykiss exposed to catch‐and‐release angling. Fish were sampled by angling on Palisades Creek (August 2016), Sawmill Creek, and the Main Fork of the Little Lost River, Idaho (July−August 2017). After capture, fish were kept underwater while they were measured and individually tagged. Anglers, in groups of two to four, caught study fish and gave them an air exposure treatment of 0, 30, or 60 s. Single‐pass backpack electrofishing was then used to recapture tagged fish and estimate relative survival. In total, 328 Yellowstone Cutthroat Trout were sampled (0 s: n = 110; 30 s: n = 110; 60 s: n = 108), 278 Bull Trout (0 s: n = 92; 30 s: n = 94; 60 s: n = 92), and 322 Rainbow Trout (0 s: n = 103; 30 s: n = 106; 60 s: n = 113). The majority of fish were caught using artificial flies (≥92%) and were hooked in the corner of the mouth, lower jaw, or upper jaw (≥78%) in all three species. No difference in survival was observed among air exposure treatments for all three species. Results from the present study along with those from prior field studies of air exposure times during angling suggest that mortality from exposing fish to air for ≤60 s is not likely a population‐level concern in catch‐and‐release fisheries for these species.

Idaho↗
USGS2018

Effectiveness of ultrasonic imaging for evaluating presence and maturity of eggs in fishes in remote field locations

Ultrasonic imaging is an effective, nonlethal method used to determine sex and maturity in a variety of fishes. However, many previous studies of this technique have been performed in laboratory environments. Using Common Carp Cyprinus carpio , we developed a standardized method for ultrasonically scanning cyprinids, and we accurately sexed 78% ( N = 58) of those individuals. We then applied this method to endangered Humpback Chub Gila cypha and obtained 751 scans of Humpback Chub in remote field locations within the Grand Canyon, Arizona. Ultrasonic scanning took less than 1 min per fish to perform, and we identified females containing eggs based on two jpeg images and one 10-s video clip. Using ImageJ software to evaluate ultrasonic scans of ovulatory, captive Humpback Chub, we determined that female fish were potentially ovulatory when scanned eggs exhibited an ImageJ brightness value within the range of 32–44. Although we could successfully evaluate egg maturity, we were unable to estimate egg mass. Fisheries managers can use this noninvasive scanning method or a similar technique in remote field locations to collect ultrasonic scans from cyprinids to determine their reproductive status.

North American Journal of Fisheries Management↗
USGS2018

Changes in growth of Rainbow Trout in a Catskill Mountain Reservoir following Alewife and White Perch Introductions

Rainbow Trout Oncorhynchus mykiss were introduced to the Esopus Creek watershed in the Catskill Mountains of New York in the early 1880s. This introduction created a renowned naturalized fishery that remains important to the local economy today. The objective of this study was to determine whether the growth and condition of Rainbow Trout in the Ashokan Reservoir changed following the establishment of (1) Alewives Alosa pseudoharengus in the 1970s and (2) White Perch Morone americana in the 2000s by analyzing historical scale samples from 502 Rainbow Trout. The resulting data were used to compare length at age, von Bertalanffy growth curves, age‐specific annual growth increments, and relative weight before and after each introduction. Results indicated that growth of Rainbow Trout of ages <5 years generally increased following each introduction, while insufficient data for ages 5 and 6 made trends for older fish unclear. Rainbow Trout of ages ≤2 are believed to primarily use riverine habitats in this watershed, and therefore fish of ages >2 may best reflect reservoir growth. The mean relative weight of Rainbow Trout also increased between each period. The largest increases in both growth and condition were observed during the period after the introduction of White Perch, which was unexpected considering this species may have some diet overlap with Rainbow Trout and should be a poor forage species. Changes in watershed management and density‐dependent growth effects may explain these unexpected results. Our results, which largely suggest increased growth and condition over time, eliminate growth effects as a possible explanation for declining Rainbow Trout populations and suggest recruitment issues in the watershed require further investigation. This study contributes to our understanding of the interactions between introduced species and underscores the value of maintaining long‐term monitoring programs for assessing biological trends.

New York↗
USGS2018

Population characteristics and management of lentic populations of nonnative Burbot in the Green River system, Wyoming

Fishes introduced outside of their native distributions have the potential to negatively affect their recipient ecosystems. Since their illegal introduction into the Green River, Wyoming, in the 1990s, Burbot Lota lota have been sampled in lotic and lentic environments throughout the Green River system where they pose a threat to native fishes and valuable sport fisheries. In response to this invasion, managers of the Green River have begun to explore the efficacy of a suppression effort targeting Burbot. This study sought to the describe population dynamics of Burbot in the lentic portions of the Green River system and compare with Burbot population dynamics in the Green River. We also sought to evaluate potential management scenarios for a suppression program. Burbot for this study were collected from Fontenelle and Flaming Gorge reservoirs in October and November 2016. Growth rates of Burbot in the lentic portion of the system were higher than for fish in the Green River. Total annual mortality rates of Burbot were approximately 10% lower in reservoirs (33%) than for fish in the Green River. Additionally, lentic Burbot matured earlier than lotic Burbot. An age-structured population model indicated that Burbot populations were growing rapidly (λ = 1.18) in the study reservoirs. Annual exploitation of juvenile Burbot would need to reach 7%. Exploitation of mature Burbot would need to increase to 33% or greater (A ≥ 57%) to effectively suppress Burbot in this system. Sensitivity analysis suggested that mortality of age-1 and age-2 Burbot had the greatest influence on population growth rate. However, due to difficulties in collecting juvenile Burbot in the system, focusing removal effort on mature Burbot may be the most realistic option for suppressing Burbot populations in the Green River system.

Wyoming↗
USGS2019

Size selectivity of sampling gears used to sample Kokanee

Kokanee Oncorhynchus nerka provide valued recreational fisheries and also serve as a prey resource for economically, socially, and ecologically important fishes. As such, management of kokanee is a major focus of natural resource agencies. Kokanee are typically monitored using midwater trawls, but the interpretation of data collected using midwater trawls is difficult due to the unknown size selectivity of the gear. We sought to assess the length selectivity of midwater trawls by comparing estimates obtained from midwater trawls with estimates obtained from gill nets adjusted for size selectivity. Experimental curtain gill nets and midwater trawls were used in conjunction to sample kokanee in seven lentic systems in Idaho. The size selectivity of gill nets was estimated by accounting for the probability of encounter and the probability of retention. Estimates of size selectivity were then used to adjust the length distribution of fish sampled in gill nets. The adjusted length distribution of fish sampled in gill nets was compared with estimates obtained from midwater trawls to identify potential size selectivity of midwater trawls. A pattern of size selectivity was apparent for both sampling techniques. The average length of kokanee sampled with midwater trawls was 111 mm; whereas, kokanee sampled with gill nets had a mean length of 235 mm. Our results suggest experimental gill nets are useful for common sampling of kokanee (e.g., trend monitoring) because the gear is less size selective than midwater trawls and is adjustable for size selectivity. However, midwater trawls are likely the best gear for addressing questions associated with early life history. Overall, our results provide a better understanding of gill-net and midwater trawl selectivity and ultimately improve the ability to sample and manage the species.

North American Journal of Fisheries Management↗
USGS2019

A statewide evaluation of Florida Bass genetic introgression in Tennessee

Largemouth Bass (Micropterus salmoides) are one of the most popular freshwater sport fish in the United States and managers in southeastern states have stocked the Florida Bass (M. s. floridanus) subspecies outside of its natural range to increase size structure of existing Largemouth Bass populations. In Tennessee, fisheries for Largemouth Bass are concentrated in reservoirs of the Cumberland and Tennessee River systems; however, Florida Bass stockings have to date been restricted to two reservoirs of the Tennessee River and have varied significantly in extent and duration. We quantified levels of genetic admixture between Florida Bass and Largemouth Bass using 38 species-diagnostic single nucleotide polymorphisms for 979 fish sampled from 14 reservoirs from the Cumberland and Tennessee River systems. We tested for differences in genetic admixture across river systems and evaluated the relative importance of fish stockings in explaining observed levels of genetic admixture. Levels of genetic admixture and associated variation was higher in reservoirs of the Tennessee River (range = 6.3 – 30.4 average percent Florida Bass alleles) relative to the Cumberland River (range = 5.7 – 13.4 %), but admixture was not solely related to stocking rates. The highest levels of Florida Bass introgression were detected in Chickamauga Reservoir, the most extensively stocked reservoir in the state. Linear models identified fish stocked as a significant overall predictor of admixture, but we also observed stocked and unstocked reservoirs with similar levels of admixture, suggesting factors other than stocking influence population genetics. Our statewide assessment of reservoir-level patterns of hybridization among black bass was performed prior to the recent expansion of Florida Bass stocking efforts in Tennessee, and thus, represents a baseline for evaluating future stocking.

Tennessee↗
USGS2019

Optimum electrofishing waveforms and parameters to induce a capture-prone response in juvenile Grass Carp

Grass Carp (Ctenopharyngodon idella) are a non-native species to North America that were first introduced for vegetation control in the 1960s. However, wild-reproducing Grass Carp can negatively impact aquatic habitats and aquatic communities by consuming substantial amounts of aquatic vegetation and increasing turbidity. Numerous fisheries techniques have been used in an attempt to control or eradicate Grass Carp, including electrofishing. However, electrofishing efficiency for Grass Carp has been variable, and optimum electrofishing waveforms and parameters for inducing a capture-prone response have not been determined. The objective of this study was to determine the optimum electrofishing waveforms and parameters to induce a capture-prone response at various water temperatures and conductivities in juvenile Grass Carp in a controlled, laboratory setting. Results indicated that rectangular pulse waveforms with 60 to 100 Hz frequencies were most effective for immobilization of juvenile Grass Carp. All duty cycles tested (20 – 48%) at these frequencies were effective; although at 60 Hz and 80 Hz frequencies, 24% and 30% duty cycles, respectively, may be more effective. Water temperature was positively related to voltage gradient immobilization thresholds whereas ambient water conductivity and fish size were inversely related to voltage gradient immobilization thresholds. This study provides important information to those seeking to control, eradicate, or detect Grass Carp using electrofishing and provides a framework for future studies focusing on adult Grass Carp.

North American Journal of Fisheries Management↗
USGS2019

Variation in Bluegill catch rates and total length distributions among four sampling gears used in two Wisconsin lakes dominated by small Ffsh

Many Bluegill Lepomis macrochirus populations are dominated by fish ≤125 mm total length (TL) that may be underrepresented when using standard sampling gears. To identify efficient sampling methods for these populations, we compared catch per unit effort (CPUE) and TL frequency distributions of Bluegill captured in cloverleaf traps, boat electrofishing, mini-fyke nets, and beach seine hauls from two northern Wisconsin lakes supporting populations dominated by fish ≤125 mm TL. Mean Bluegill CPUE ranged from 41 (SE = 11) fish per cloverleaf trap lift to 16 (SE = 8) fish per beach seine haul. Cloverleaf traps generally captured smaller Bluegill relative to other gears and were the only gear to consistently capture Bluegill ≤80 mm TL. Conversely, boat electrofishing captured the widest TL range of Bluegill, and fish ≥80 mm TL composed a greater proportion of catch (37%) relative to other gears. With few exceptions, the effort required to detect 10% or 25% changes in Bluegill CPUE was >100 units of effort regardless of lake, sampling gear, or month. Furthermore, there was no consistency between lakes or months in terms of which sampling gear required the fewest number of samples to detect a 50% change in CPUE. Estimated units of effort needed to detect 10% or 25% changes in mean Bluegill TL were ≤16 for all sampling gears on the lake with consistently higher CPUE (i.e., more fish to measure per unit). In the lake with lower CPUE, cloverleaf traps consistently required less effort to detect changes in mean TL. We note that comparing sample size requirements among gears is not straightforward because gears are sampling differing segments of the Bluegill population. Our study emphasizes the importance of evaluating gear biases and sampling efficiency so that fisheries managers can develop suitable sampling protocols.

Wisconsin↗
USGS2019

Observations of American Shad Alosa sapidissima approaching and using a vertical slot fishway at the head-of-tide Brunswick Dam on the Androscoggin River, Maine

American Shad Alosa sapidissima have historically supported an important fishery along the Atlantic coastal waters of North America. However, the construction of dams reduced populations and restricted landings. Fishways are intended to mitigate obstacles to anadromous fish migrations, but a thorough evaluation of their efficiency is warranted. We analyzed data collected from video recordings, hydropower turbine operations, and telemetry conducted by the Maine Department of Marine Resources to evaluate American Shad behavior while approaching and using a vertical slot fishway at the head-of-tide Brunswick Dam on the Androscoggin River in Maine. American Shad passage at the dam has been poor, ranging from 0 to 1,100 fish per year, relative to passage at other facilities in the region. Additionally, our observations indicate that there are relatively high numbers of American Shad present downstream in the river (averaging 50,000) compared with the entrance of the fishway or its pools (<8,000). On average, the rates of observed American Shad on the side of the river near the fishway entrance were significantly higher (6.5–8.6 individuals/min) when the turbine closest to the entrance of the fishway was not operating compared with when it was operating (4.1 individuals/min). Most of the radio-tagged American Shad remained in the river below the dam or went undetected. Eleven of 57 tagged fish were detected at the fishway entrance and of those only five were detected in the lower fishway. Individuals that were detected were observed making multiple attempts at entering the fishway, but movements were restricted to the lower pools. Our results suggest that this fishway is not conducive to the passage of American Shad. Examining the relationship between hydropower operations and other environmental variables on the behavior and passage of migrating anadromous fish remain an area for further study.

Maine↗
USGS2019

A brief introduction to integrated pest management for aquatic systems

Aquatic invasive plants and animals are increasingly becoming a problem, causing severe economic and ecological damage to critical freshwater systems. The best strategy for controlling an invasive pest employs an integrated pest management (IPM) approach using a combination of biological, physical, chemical, and social/cultural control methods. Here, we examine the history and development of IPM and provide a discussion of the components of an IPM program involving development, evaluation, and management. Control approaches will be reviewed and the application of this technique to aquatic systems will be discussed. A discussion of the Great Lakes Fishery Commission's (GLFC) Integrated Management of Sea Lamprey Petromyzon marinus Control Program will be provided to illustrate the application of IPM to an aquatic system.

North American Journal of Fisheries Management↗