Search

Objective: Successful conservation and management of fishes require an understanding of their age and growth. However, methods for estimating the age and growth of long‐lived fish species are difficult to validate. The Kootenai River basin has a decades‐long mark–recapture program for endangered White Sturgeon Acipenser transmontanus. The mark–recapture history information for White Sturgeon allowed for the evaluation of fin rays for age and growth analysis. Methods: Age was estimated from pectoral fin rays of known‐age White Sturgeon (n = 162) to evaluate ageing accuracy and precision. Lengths were back‐calculated using four models and measurements obtained from two fin ray transects (i.e., lateral and posterior). Result: Between‐reader agreement for White Sturgeon ages was 58.7%. Consensus age agreement with known ages was poor (30.7%) and decreased with age. Among the four back‐calculation models, the Fraser–Lee model provided the lowest root mean square error and percent error. Estimates of mean back‐calculated lengths at age derived from the Fraser–Lee model were similar between the two measurement transects. Back‐calculated lengths at age were similar to known lengths at age. Conclusion: Ageing of White Sturgeon using fin rays was unreliable, and accuracy decreased with fish age. Back‐calculated lengths at age were accurate using measurements from fin rays of known‐age fish. Length estimates from the two measurement transects were similar when using the Fraser–Lee method, suggesting that they may be used interchangeably. Impact statementValidation of age and growth information for long‐lived species is difficult. Although age estimates regularly underestimated true age of White Sturgeon, particularly for fish older than age 10, growth estimates were similar to known lengths at previous ages. As such, fin rays are likely suitable for evaluating age and growth of White Sturgeon, but results from such analyses should be interpreted with appropriate caution. [ABSTRACT FROM AUTHOR]

Objective: Hatcheries are used to help supplement populations of Pacific salmon Oncorhynchus spp. for conservation and fisheries purposes and to provide stewardship opportunities. In British Columbia, small community-run hatcheries typically focus on the latter and generally do not know the efficacy of their release approaches, unlike larger production hatcheries. Methods: We used acoustic telemetry to track the survival and behavior of 90 hatchery-reared Coho Salmon O. kisutch smolts, released from a community hatchery, through Burrard Inlet and into the Strait of Georgia. This is the first study to track Coho Salmon smolts released directly into a marine environment and one of very few studies to track them in an oceanic setting. Result: Smolt survival was lowest through the first 3 km of the migration at 37%, and the estimated cumulative survival to the final array (~20 km from release) was 10-23%. The presence of numerous predators in the region suggests that predation is a possible explanation for poor survival over the relatively short migration distance. Travel rates ranged from ~4 to 18 km/day, depending on the migration segment, which is slower than the marine migration of smolts from other species, likely increasing exposure to predators. However, we found potential evidence of "predator swamping," as survival estimates across migration segments were highest for the final of our three release groups and poorest for the first release group, with intergroup survival estimates increasing by 7-12% in the final three migration segments. Releasing smolts at high densities and at night, as our partner hatchery currently does, likely improves smolt survival. Conclusion: Our work demonstrates how acoustic telemetry can be used to examine hatchery practices and propose potential improvements. Saltwater readiness and the release location are factors that our results suggest may warrant future attention to potentially improve marine survival of Coho Salmon smolts. [ABSTRACT FROM AUTHOR]

Objective: Natural dispersal or unauthorized introductions of nonnative predatory sport fish can undermine native species conservation and other fisheries management objectives. The use of reproductively sterile triploid fish may provide a lower risk stocking option (i.e., genetic and reproductive containment) for diversifying angling opportunities while possibly reducing angler motivation to illegally transplant fish. Management interest in triploid Walleye Sander vitreus is growing, and these fish are currently stocked by several fisheries agencies. However, little is known about the poststocking growth, body condition, and survival of triploid Walleye—information that is important for calibrating expectations and guiding policy regarding their use. Methods: We compared the age‐specific size, body condition, and survival of subadult (i.e., ages 0–3) triploid Walleye to those of normal diploid conspecifics in two eastern Colorado reservoirs. Paired stockings of triploid and diploid Walleye occurred over 3 years. Both fry and fingerlings were stocked each year. Result: Triploids were generally smaller in length (6.6% smaller on average) and weight (20.6% smaller) compared to diploids across all age‐classes. Despite being smaller, triploids had similar body condition relative to diploids. On average, the survival of triploids from spring stocking to their first fall was 6.3× lower than that of diploids, but no differences in survival were observed beyond this early life stage. This pattern was consistent across cohorts and reservoirs. Conclusion: The present work provides a foundation for future studies that are designed to clarify patterns of survival from spring to the first fall by accounting for size at stocking and natural‐origin fish and studies that are planned to assess the poststocking performance of triploid Walleye independent of diploids. Impact statementBalancing recreational fisheries management with native species conservation efforts can be challenging, especially in cases where anglers highly value nonnative predators. The practice of stocking sterile fish is an emerging management approach aimed at addressing concerns about introducing or maintaining existing populations of predatory fish outside of their native range. While artificially induced triploidy is among the most common methods for producing sterile fish, little is known about how triploid fish grow and survive in the wild, information that is crucial for decision making regarding their use. In this study, we provide some of the first information regarding the size, body condition, and survival of triploid Walleye relative to normal, diploid Walleye in the wild. Our findings will aid managers in making decisions regarding the use of triploid Walleyes in their programs. [ABSTRACT FROM AUTHOR]

Objective: A goal of many segregated salmonid hatchery programs is to minimize potential interbreeding between hatchery‐ and natural‐origin fish. Our objective was to assess this on the Klickitat River, Washington, USA. Methods: We used radiotelemetry to evaluate spatiotemporal spawning overlap between hatchery‐ and natural‐origin steelhead Oncorhynchus mykiss and spring Chinook Salmon O. tshawytscha. We estimated percentages of tagged fish that spawned naturally in the Klickitat River subbasin, emigrated from the Klickitat River, or died before spawning. A kernel density analysis was used to estimate probability of spatiotemporal overlap between hatchery‐ and natural‐origin spawners. Result: For steelhead, 12% of hatchery‐origin and 50% of natural‐origin fish spawned naturally. For spring Chinook Salmon, 18% of hatchery‐origin and 44% of natural‐origin fish spawned naturally. Tag loss may result in underestimates in these percentages. Most hatchery‐origin steelhead (90%) spawned downstream of river kilometer (rkm) 32, and 75% spawned from November to mid‐March. The majority of natural‐origin steelhead (64%) spawned upstream of rkm 32, and 75% spawned from mid‐March to late May. Spawn timing of hatchery‐origin Chinook Salmon (early August to mid‐September) overlapped with that of natural‐origin Chinook Salmon (late July to late September), and fish of both origins spawned in the same 30‐km reach of the river. We estimated the percentage of hatchery‐origin spawners (pHOS) on the natural spawning grounds to be 12% for steelhead and 40% for spring Chinook Salmon across all study years. For steelhead, we estimated the overlap probability to be 25% (95% CI = 22.5–28%). For spring Chinook Salmon, tight spatial clustering of hatchery‐origin fish resulted in a lower overlap estimate of 21% (13–31%). Conclusion: We suggest adjusting pHOS estimates using these overlap estimates or similar spatiotemporal data on actual spawner proximity and possible interactions, and that these types of analyses be used in conjunction with gene flow analysis to accurately evaluate effects of individual hatchery programs. Impact statementPacific Salmon and steelhead hatchery programs provide important fishery and conservation benefits. We monitored interactions between hatchery and wild populations by tracking radio‐tagged fish and their degree of actual physical overlap in space and time to better inform management and recovery of this critical resource. [ABSTRACT FROM AUTHOR]

Objective: Recent technological developments may facilitate the description of evolutionary relationships and population genetic structure as well as other information relevant to fisheries management by using readily available natural history collections. Contemporary sequence capture and short‐read sequencing methods offer opportunities to analyze highly fragmented DNA from formalin‐fixed specimens so long as enough DNA of sufficient quality is recovered. Methods: We compared two protocols developed to extract DNA from formalin‐fixed tissues using specimens of three freshwater fishes: the Southern Brook Lamprey Ichthyomyzon gagei, Slimy Sculpin Cottus cognatus, and Brown Trout Salmo trutta. Extractions were attempted using hot alkali digestion with and without buffer wash pretreatments to compare the DNA concentration, purity, and fragment length of DNA recovered between extraction protocols, tissue types (muscle and caudal fin tissue for Brown Trout and Slimy Sculpin), and preservation periods (5 or 7 years for Southern Brook Lamprey). Result: Likelihood models generally did not detect DNA quantity differences between extraction protocols nor tissue types; however, 6.0–8.7× more DNA was recovered from Slimy Sculpin caudal fins than from muscle tissue. Extraction protocol had mixed effects on DNA purity; the wash protocol outperformed the no‐wash protocol for Slimy Sculpin and Brown Trout, but the reverse was true for the lamprey. Purer DNA was recovered from the caudal fins; however, fragment lengths were generally greater from muscle tissue for both ray‐finned species. Conclusion: Our results suggest that the best tissue for sampling may depend on the quality metric considered most important for a study's objectives and that omitting time‐consuming tissue wash steps can yield DNA of quantity and quality comparable to DNA from more complex methods. Regardless of species, the DNA extracted from most samples using both protocols met quantity and quality thresholds that are likely to result in short‐read sequencing success. These results provide optimism for unlocking the wealth of genetic information in natural history collections for use in fisheries management and conservation genomics. Impact statementContemporary sequence capture and short‐read sequencing methods may facilitate inference of evolutionary relationships, population genetic structure, and other information relevant to fisheries management from formalin‐fixed natural history collections as long as enough DNA of sufficient quality is recovered. We assessed extraction protocols for two ray‐finned fishes and one lamprey, and determined factors likely to result in sequencing success. [ABSTRACT FROM AUTHOR]

Objective: Little is known about the marine ecology of anadromous Pacific Lamprey Entosphenus tridentatus and Western River Lamprey Lampetra ayresii. This information is needed to determine how marine life regulates adult abundances and to identify management actions that may benefit declining populations. Methods: To address this deficit, we compiled historic data, collected lamprey from marine stock assessment surveys and commercial fisheries, and documented fish with Pacific Lamprey wounds. Result: Pacific Lamprey were most commonly caught by midwater trawls targeting Pacific Hake Merluccius productus along the continental shelf break from northern California to northern Washington. Pacific Lamprey ranged in size from 115 mm total length (TL) and 2.9 g to 714 mm TL and 655 g (n = 1912) and were expected to represent multiple ocean ages. The vast majority (93%) of Pacific Lamprey were small (≤300 mm TL) and thus were likely in their first year in marine waters. Growth for small Pacific Lamprey was estimated as 0.37 mm/day and 0.13 g/day over the summer. Gut fullness for Pacific Lamprey was high (5.5% of body weight [BW]), but it was highly variable for larger individuals (range = 0–55% BW). Our results suggest that there is a positive relationship between calendar day and lamprey length and condition factor in most years, while the effect of latitude varies by life stage. We documented Pacific Lamprey wounds on 240 individual fish representing 16 species, of which six species are newly identified as lamprey hosts. We had comparably few records for Western River Lamprey (n = 72; mean length = 285.5 mm TL), which were primarily found in surface waters on the continental shelf from northern California to southern British Columbia. Conclusion: Our results have implications for both fisheries and conservation management, including development of best practices for lamprey caught by net fisheries and the use of new marine information to inform conservation actions. Impact statementWe show that native Pacific Lamprey are widespread in marine waters along the U.S. West Coast. They are caught as bycatch in Pacific Hake and other commercial fisheries, requiring development of methods to ensure that Pacific Lamprey released from fisheries survive to ensure the continued existence of this ancient fish. [ABSTRACT FROM AUTHOR]

Objective: Dewatering of fine sediments in rivers and streams can kill many thousands of larval lampreys (order Petromyzontiformes) that are burrowed in these habitats. The larval life stage for lampreys lasts 3–10 years, and because larvae often aggregate in large numbers, negative impacts from dewatering could potentially deplete local populations and affect multiple year‐classes. Larval lampreys have not traditionally been considered during instream projects, but recent efforts to increase awareness of lamprey habitats have resulted in guidance on dewatering approaches to limit impacts to lampreys. Salvage efforts to rescue and relocate lampreys aim to mitigate losses, but a lack of understanding of lamprey responses limits the optimization of dewatering and salvage procedures. Methods: We summarize the state of the science for nine factors that influence larval lamprey (Entosphenus and Lampetra spp.) responses to dewatering, including burrowing depth, the prevalence and timing of emergence, movements, survival, shoreline slope, dewatering rate, light, and lamprey size. Result: Research suggests that (1) shoreline slope influences movement capability, (2) hot and sunny conditions increase the risk of mortality, (3) salvage activities cause minimal direct mortality, and (4) smaller larvae are especially vulnerable to negative impacts from dewatering because they are more likely to emerge and are less capable of movement. Critical uncertainties associated with dewatering include cues that drive emergence, the influence of sediment composition and stratigraphy, vertical distribution of larvae in natural settings, use of the hyporheic zone, the scale of predation losses, and the effectiveness and impacts of salvage activities. Conclusion: Balancing investments in salvage operations and lamprey exclusion efforts (e.g., screening) and developing field survey approaches to evaluate lamprey use of the hyporheic zone are identified management implications and research needs. Addressing the critical uncertainties discussed here and providing updated, science‐based guidance on dewatering and salvage practices are suggested management actions to support lamprey conservation. Impact statementLarval lampreys live burrowed in fine sediments and are often not considered during instream projects that dewater these habitats. This paper synthesizes what is known about lamprey responses to dewatering to provide updated, science‐based guidance on dewatering approaches to minimize negative impacts to lamprey and support conservation efforts. [ABSTRACT FROM AUTHOR]

Objective: Silver Chub Macrhybopsis storeriana, a predominately riverine species throughout its native range, exists within Lake Erie as the only known lake population. Its population declined in the 1950s and never fully recovered. Canada has listed Silver Chub in the Great Lakes–St. Lawrence River as endangered and has initiated a recovery plan that recognized the identification of spawning areas as a critical component to inform Silver Chub's recovery potential. Methods: We investigated potential spawning locations of Silver Chub using capture records, otolith microchemistry, and daily age analysis. Lapillus otolith Sr:Ca ratios from 27 age‐0 Silver Chub were used to identify potential spawning areas. Daily ages estimated from lapilli were used to calculate hatch dates, which then were compared with capture data of adults and river flows to further inform potential spawning areas. Result: The Detroit River (and its nearshore area) was all but ruled out as a potential spawning location. The Maumee, Portage, and Sandusky rivers or their nearshore areas were all possible spawning locations. Projected hatch dates spanned the end of May through the end of June and occurred across a wide range of flows, although some peaks in hatch dates corresponded to flow peaks, indicating recruitment is potentially enhanced by high flows. Conclusion: Silver Chub spawning period and hypothesized spawning rivers or lacustuaries overlap those of invasive Grass Carp Ctenopharyngodon idella, creating a need to jointly consider Grass Carp control efforts with conservation of Silver Chub when assessing management alternatives. Further research on spawning guild and the use of rivers themselves or nearshore areas influenced by rivers as spawning areas are required to maximize potential for conservation and recovery of Silver Chub. Impact statementConserving the Silver Chub is vital; it's an indicator of water quality, a food source for aquatic organisms, and preserves biodiversity. Identifying both locations and mode of spawning enhances the conservation of biodiversity in fish communities, ensuring ecosystem stability. [ABSTRACT FROM AUTHOR]

Objective: A recent expansion of the northern stock of Black Sea Bass Centropristis striata into the northern Gulf of Maine raises questions about this species' movement and population dynamics in this region. Determining the origin of these fish is essential, as dramatic changes in migration patterns or current population boundaries could have profound effects on stock assessment estimates and subsequent management regulations. Methods: In this study, we measured otolith core concentrations of stable isotopes (δ18O, δ13C) and trace element:calcium ratios (Mg:Ca, Mn:Ca, Cu:Ca, Zn:Ca, Ba:Ca, Sr:Ca) to assess the natal origin of Black Sea Bass that were caught off the coast of Maine. Spawning condition adults from southern New England (SNE) and the mid‐Atlantic Bight (MAB) were used to characterize the chemical fingerprint of these known spawning regions. Result: Unique chemical fingerprints were identified for fish from SNE and the MAB, with high reclassification success using random forest analysis (16% error rate). The classification of Black Sea Bass of unknown origin that were caught in Maine waters indicated that 85% of the samples matched to SNE and 13% to the MAB, whereas one sample remained unclassified. Conclusion: Results from this study support the current management population separation of the northern stock of Black Sea Bass between SNE and the MAB and lends additional information to the understanding of this species' movement into the northern Gulf of Maine. As fish stocks around the world continue to shift into new regions due to climate change, knowledge of their natal origin will be critical to long‐term sustainable management of this species. Impact statementDetermining which population Black Sea Bass located in Maine came from helps scientists understand how these fish migrated there, their potential for success, and their expected growth and maturity. If this species becomes more abundant in the region, this information could help inform regulation surrounding conservation and fishing practices. [ABSTRACT FROM AUTHOR]

Objective: Population demographics of trout were analyzed across multiple spatial scales to evaluate fishery resources in the three forks and main stem of the upper Snoqualmie River, Washington. Physical habitat and trout species compositions, relative abundances, and sizes were assessed through spatially continuous sampling of the watershed. Fish were also sampled at the segment scale (5–20 km) for more detailed but spatially intermediate assessments of species and genetic origin, size at age, and seasonal diet. To evaluate growth conditions during summer months, bioenergetics simulations of consumption by trout were run using summer water temperatures, and growth and diets were sampled at two life stages. Result: We found high variability in longitudinal species compositions, genetic origins, relative abundances, and densities within and among forks. While annual growth generally decreased with distance upstream, summer growth efficiency consistently increased. Areal density estimates of age‐0 recruits in the North and Middle forks generally increased with segment elevation, whereas density of recruits was relatively low in upper elevations of the South Fork, where nonnative Westslope Cutthroat Trout Oncorhynchus clarkii lewisi were most abundant. Abundance of trout varied widely among the forks, and a native metapopulation of Coastal Cutthroat Trout Oncorhynchus clarkii clarkii was the most abundantly distributed species across interconnected main‐stem habitats. Conclusion: Factors affecting population demographics of trout at the riverscape scale included geologic barriers, habitat diversity, and stocking practices, while summer growth was primarily affected by water temperature. Merging riverscape‐ and intermediate‐scale sampling enhanced watershed‐scale inferences made from intermediate sampling while accounting for continuous variability. This design provided a holistic assessment of the trout resources that would not have been possible using either site‐specific sampling or continuous longitudinal surveys and provided a baseline assessment of trout resources in the upper Snoqualmie River watershed for continued management and conservation of the fishery. Impact statementUsers of wild trout fisheries in montane streams often wonder which areas support more, larger, or different species and why. Our study provided novel, empirical insights into why we see certain species where we do, why they are more or less abundant in some areas, and why some grow larger than others in some areas. [ABSTRACT FROM AUTHOR]

Physical and hydrologic connectivity among river–reservoir ecosystem (RRE) segments, including the river, river–reservoir interface (RRI), and reservoir, requires consideration of management at larger spatial scales. Multiple objectives (e.g., ecosystem function, sport fisheries, and maximizing fish diversity) seem well suited to this broad spatial scale; however, data limitations regarding the distribution of taxa within RREs currently hamper such an approach. We quantified the fish assemblage of the Trinity River–Lake Livingston ecosystem in Texas, USA, using a stratified approach to determine the contribution of individual segments to the overall fish assemblage. In general, fish assemblages varied along a continuum from the river to the reservoir; however, fish assemblages in several river backwaters did not follow this gradient, thus adding diversity to the overall RRE. Variability in fish assemblages among ecosystem segments was the result of both species composition and relative abundance. Species richness (N = 58 total) was highest in the river segment (N = 49) followed by the RRI (N = 46) and was much lower in the reservoir (N = 36). In contrast, average catch per standardized unit of sampling effort (all species combined) was greatest in the RRI, about 25% lower in the reservoir, and about 50% lower in the river. Across the ecosystem, 26 species (45%) were considered common, while 32 species (55%) were considered rare. Notably, species of conservation need were not always most abundant in river habitats, and species supporting recreational fisheries were not always most dominant in the reservoir. These findings suggest that the RRE can serve as an appropriate spatial scale for both conservation and recreational fishery management actions. [ABSTRACT FROM AUTHOR]

Columbia River hatcheries release millions of juvenile Chinook Salmon Oncorhynchus tshawytscha to support fisheries and mitigate for historical productivity declines from dam construction and upriver habitat losses. Recent federal biological opinions for Federal Columbia River Power System operations also have mandated restoration of estuarine rearing habitats to mitigate for mortality of naturally produced (NP) salmon at main‐stem dams. We compared genetic stock compositions, distributions, abundances, and length frequencies of hatchery‐marked and unmarked Chinook Salmon to evaluate the extent of hatchery influence on nearshore estuarine habitat use and the potential for interactions between hatchery‐origin (HO) and NP salmon. Cumulative Chinook Salmon releases from all hatcheries in 2010 and 2011 dictated estuarine stock composition, abundance, and life histories during the spring–summer migration peak. Naturally produced salmon from the lower Columbia River populations, including many fry migrants, were most abundant, but larger HO juveniles also frequented nearshore sites, where their total biomass often equaled or exceeded that of NP fish. Large releases of a single stock of origin (Spring Creek Group fall run) in April and May created sharp pulses in the estuary entry timing of fingerling‐sized salmon and dominated abundance and stock composition at some sites. Successive releases from scores of hatcheries during spring and early summer ensured a consistent presence of HO salmon near shore, regardless of the habitat‐specific residence times of individual fish. Overall, the historical replacement of diverse wild populations with fewer hatchery stocks of a narrow size range and migration timing has intensified nearshore habitat use during the spring–summer migration peak and reduced life history variation of Columbia River Chinook Salmon. Such changes could undermine the fish conservation goals of both hatchery mitigation and estuary restoration programs. [ABSTRACT FROM AUTHOR]

Survival of fish in the first year is critical in determining the year‐class strength of fish populations. In river–floodplain ecosystems, affiliated lakes (i.e., floodplain lakes that are hydrologically connected to the river) play a crucial role as nursery habitats for young‐of‐the‐year (age‐0) fish. However, most lakes in the river–floodplain ecosystem of the Yangtze River, China, have been disconnected. Data on age‐0 fish distribution are important for developing appropriate strategies for management and conservation of fish populations in the river. We investigated the distribution patterns of age‐0 fish in the middle reaches of the Yangtze River. Overall, 33 species were collected from four main‐stem reaches (29 species) and two lakes (32 species) connected with the main stem from July to September in 2010 and 2011. The CPUE and species richness of age‐0 fish were higher in the lakes; age‐0 species richness showed an increasing trend in a downstream direction along the main stem. Analysis of similarities revealed that significant differences in assemblage structure of age‐0 fish occurred mainly among sampling sites. The higher CPUE and species richness of age‐0 fish in the lakes indicate the importance of connected lakes as age‐0 fish nursery habitats. We also found abundant age‐0 fish in the main stem and a relationship between spatial patterns of age‐0 fish with site proximity to the Three Gorges Dam, similar to previously observed spatial patterns in larval fishes. These results indicate the importance of the main stem as age‐0 fish nursery habitat and the effects of the dam on age‐0 fish distribution. This study presents the first data on age‐0 fish in the Yangtze River, thus providing a baseline for future age‐0 fish research. It also provides essential information for management and conservation measures, such as restoring the lateral connectivity between the main stem and disconnected lakes and guidelines for ecological operation of the dam. [ABSTRACT FROM AUTHOR]

The National Marine Fisheries Service is mandated by the Magnuson–Stevens Fishery Conservation and Management Act to implement effective annual catch limits and accountability measures to prevent overfishing. These requirements compel further research into alternative fishing practices that could reduce mortality of sharks (class Chondrichthyes) and allow fishers to release unwanted sharks to the water alive, while still effectively catching targeted species. We used hook timers and temperature–depth recorders aboard contracted vessels and participants in the National Marine Fisheries Service's Shark Research Fishery to collect hooking time and time‐on‐the‐line data for 10 species of sharks that were commonly encountered in the fishery. A subset of standardized fishing sets compared the most popular circle hook and J‐hook models. Over 60% of sharks were hooked within 4 h of hook soak time. The fastest to bite the hook was the Atlantic Sharpnose Shark Rhizoprionodon terraenovae and the slowest was the Dusky Shark Carcharhinus obscurus. Shark resilience to time on the longline varied among species, with Sandbar Shark C. plumbeus exhibiting the most resilience and Atlantic Sharpnose Shark the least. Shorter set soak times, approximately 2 h, would still maximize catch, while minimizing at‐vessel mortality. The most frequently used circle hook model did not significantly reduce at‐vessel mortality over large J‐style hooks. The recent circle hook requirement will have little effect for fishers that previously used 12/0 J‐hooks, but it may be beneficial by preventing the use of smaller J‐hooks that are more likely to cause at‐vessel mortality. [ABSTRACT FROM AUTHOR]

We used historical stocking and population survey records of Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri and other salmonids in the North Fork Shoshone River drainage, Wyoming to summarize fish stocking history and population trends. Based on 98 years of historical records, we found that despite extensive stocking of Yellowstone Cutthroat Trout and minimal stocking of nonnative salmonids after about 1950, populations of wild Yellowstone Cutthroat Trout declined relative to those of nonnative salmonid species. The timing of increases in nonnative salmonids (1970s) did not coincide with their period of most intensive stocking (1935–1950). It is plausible that Yellowstone Cutthroat Trout populations persisted because of high levels of supplemental stocking from 1935 to 1965 and declined with reduced stocking efforts in the 1970s, thereby allowing the increase of introduced nonnative salmonids. The establishment of nonnative salmonids likely further reduced stocking success of Yellowstone Cutthroat Trout due to competition and hybridization. This study demonstrates that an understanding of long‐term stocking records and population survey data can be useful for developing and implementing successful management frameworks for the conservation of imperiled fish populations across the United States. [ABSTRACT FROM AUTHOR]

Adult summer‐run steelhead Oncorhynchus mykiss overwinter in freshwater for several months prior to spawning. In systems supporting mixed populations of fisheries and conservation importance, understanding the distribution and survival of pre‐ and postspawn fish is necessary for informed management. The upper Columbia River supports hatchery‐origin components valued by anglers, natural‐origin components of conservation concern, and temporary strays from downstream populations. We used radiotelemetry and PIT telemetry to monitor the behavior, distribution, and survival of adult steelhead during fall, overwintering, spawning, and postspawn periods, with a focus on use of the main stem versus four major tributaries. Adult steelhead (N = 807) were tagged at Priest Rapids Dam in 2015 and 2016. One‐fifth of steelhead fell back below Priest Rapids Dam and did not reascend. A slight majority of tagged steelhead that overwintered upstream of Priest Rapids Dam did so in main‐stem reservoirs (54%; N = 548). Overwintering in the main‐stem Columbia River was more likely for later‐arriving steelhead and was concentrated in the upstream‐most reservoir. Winter tributary use was highest in the Wenatchee (26%; 2016) and Methow (18%; 2015) rivers, whereas no steelhead overwintered in the Entiat River. Harvest of hatchery‐origin steelhead was 18% in 2015 and was near zero in 2016, when the fishery was suspended due to low adult returns. After accounting for reported harvest, annual overwinter survival did not differ between main‐stem and tributary habitats, and relatively low adjusted survival of hatchery‐origin steelhead in 2015 suggested unreported harvest. In contrast to low iteroparity rates (<3%), the majority of postspawn steelhead (56.5%) exited tributaries as kelts; kelt survival to Bonneville Dam was 65% in 2016 and 23% in 2017. Collectively, the results highlight the importance of understanding patterns of habitat use and mortality in steelhead populations when managers are faced with balancing harvest and conservation goals. [ABSTRACT FROM AUTHOR]

Stream drying, especially in the western United States, is becoming more common as the climate warms and precipitation patterns become less predictable; consequently, fisheries managers need to prioritize conservation efforts where water (and fish) will persist in the future. Yellow Creek in the upper Bear River watershed (Utah and Wyoming) contains one of the largest remaining populations of Northern Leatherside Chub Lepidomeda copei, an imperiled fish. Lower reaches are drying during summer months, partly due to water withdrawals, thus reducing Northern Leatherside Chub populations and relegating the remaining fish to isolated pools until the water returns. This study used an unmanned aerial vehicle to capture high‐resolution and spatially explicit imagery over 19 km of Yellow Creek in a few weeks during late August when the water is the most limiting to the fish. Through imagery and subsequent GIS analysis, we identified 405 previously unknown potential refuge‐pool habitats for Northern Leatherside Chub and determined their location, size, and spatial distribution, thereby helping managers prioritize stream reaches for native fish conservation and restoration. While the cost of unmanned aerial vehicle flights was estimated to be 2.5 times that of on‐the‐ground surveys in 2016, unmanned aerial vehicle technology continues to become more cost effective and, unlike traditional surveys, provides high‐resolution and spatially referenced data. [ABSTRACT FROM AUTHOR]

Managing fisheries for species of conservation concern, such as steelhead Oncorhynchus mykiss fisheries in Idaho where wild steelhead are incidentally caught and released, requires a tradeoff between providing opportunity for anglers to fish for hatchery‐origin steelhead and managing conservation risk for wild steelhead. Understanding population‐level effects of catch‐and‐release fishing is critical for effectively balancing this tradeoff. We used an integrated population model to evaluate population‐level effects of incidental catch‐and‐release mortality on steelhead in Idaho and assessed the effectiveness of alternative management strategies for meeting fishery and population objectives. When simulated catch‐and‐release mortality or encounter rates were low, fishery, abundance, and conservation risk objectives were easily met by implementing fisheries annually, regardless of adult abundance. However, when simulated catch‐and‐release mortality rates were high, management strategies that required the population to surpass minimum thresholds for pre‐season abundance were more likely to meet goals for minimizing conservation risk but limited fishing opportunity substantially. Results of this study provide managers with a framework that can be used to manage fisheries to meet fishery goals in the form of hatchery steelhead harvest while maintaining sustainable populations and minimizing risk to wild steelhead. The results also suggest that when implemented properly, it is possible to meet fisheries and conservation objectives simultaneously. [ABSTRACT FROM AUTHOR]

The Lemon Shark Negaprion brevirostris is a large coastal shark that commonly occurs in the shallow nearshore waters of the tropical western Atlantic Ocean. There are conservation concerns for this species due to fisheries exploitation, low productivity, anthropogenic disturbance at nursery sites, and the depleted status of other large coastal sharks, but no quantitative assessment of Lemon Shark stock status is available. We synthesized available data to develop a stock assessment of the Lemon Shark in the western North Atlantic. All information on stock identity was considered to define a fishery management unit off the southeastern United States. Stock abundance and trends in fishing mortality were estimated from 1981 to 2017 using a Bayesian state–space surplus production model. The model incorporated prior knowledge of Lemon Shark demography, catches, and a combination of 11 indices of abundance. Seven model configurations that fit the data well and produced plausible estimates were used to evaluate the sensitivity of posterior estimates to assumed priors and data decisions. Results suggested that Lemon Shark stock abundance has been relatively stable since the mid‐1990s, with some estimates of prior depletion. Estimates of relative fishing mortality indicate earlier periods of overfishing, with a decrease in fishing mortality since the early 2000s. These estimates of population trends provide information for future fisheries management and conservation. [ABSTRACT FROM AUTHOR]

Important variability exists in life history attributes among localized populations of Coastal Cutthroat Trout Oncorhynchus clarkii clarkii in relation to geographic and environmental factors. Describing the life history of locally adapted populations is critical to successful fishery management and conservation. The number of annuli and distance between circuli in scales (i.e., scale analysis) are often used to describe migratory behavior and age of Coastal Cutthroat Trout, but the accuracy of these estimates is largely unknown. In this study, we compared estimates of age (based on analyses of scale and otolith structure) and migratory patterns (based on scale structure and otolith structure and chemistry) for anadromous Coastal Cutthroat Trout in South Puget Sound, Washington State. We compared 48 paired scale and otolith samples (age range = 1–5 years), and age estimates agreed 79% of the time (average percent error [APE] = 5%; CV = 6%), supporting historical age estimates that were generated using scales. However, the number of migrations between freshwater and marine environments estimated using scales and otoliths agreed 44% of the time (n = 50; APE = 25%; CV = 35%). Comparisons of scales and otoliths indicated that more individuals overwinter in marine waters than previously thought based on scale analysis. The majority of fish in this study (68%) were the progeny of females that matured in marine waters and may be vulnerable to fisheries in the marine environment. Current management actions that prohibit the harvest of Coastal Cutthroat Trout in marine waters may be important for the conservation of small localized populations in South Puget Sound. [ABSTRACT FROM AUTHOR]

Burbot Lota lota were illegally introduced to the Green River, Wyoming, in the mid‐1990s and pose a threat to recreational fisheries and native fish conservation. Although much is known about Burbot population dynamics, little is known about their movement patterns. Our objectives were to describe the movement dynamics of Burbot in the upper Green River system to provide information on the ecology of Burbot and insight on possible management actions. In total, 875 Burbot were tagged with PIT tags in the upper Green River and Fontenelle Reservoir; their movements were tracked from August 2016 to March 2018. Additionally, 22 Burbot were tagged with radio transmitters in Fontenelle Reservoir in November 2017, and 13 Burbot were tagged with radio transmitters in the upper Green River in November 2018. Of these fish, 11 Burbot tagged in Fontenelle Reservoir and all river‐tagged Burbot were tracked as they migrated into the Green River and associated tributaries during the spawning season. Upstream and downstream movements of Burbot tagged with PIT tags in Fontenelle Reservoir and the upper Green River peaked during December–January and were synchronized with river temperatures reaching 0°C. Of the total number of PIT‐tagged Burbot, 10–15% of those tagged in Fontenelle Reservoir were detected in the Green River during the spawning season and 15% of those tagged in the Green River were detected moving downstream toward Fontenelle Reservoir during the spawning period. Movements of radiotelemetered Burbot were synchronized with river ice‐up in mid‐December. Maximum upstream distance traveled by adfluvial Burbot was 5.8 km. Fluvial Burbot primarily migrated downstream during the spawning period, and maximum downstream distance traveled was 17.7 km. Detection data suggest that both fluvial and adfluvial Burbot occupy the same reaches during the spawning period and areas near Fontenelle Reservoir are important for spawning. Results of this study will assist with the management of Burbot in this system by shedding light on Burbot movement patterns and identifying areas of high Burbot use for targeted suppression efforts. Results also contribute to our understanding of the variability in Burbot ecology. [ABSTRACT FROM AUTHOR]

Recreational fisheries are often managed to provide satisfying fishing experiences for anglers while conserving wild fish stocks. However, managing recreational fisheries is difficult because fish populations are often infrequently monitored and fishing effort is uncontrolled; moreover, a satisfying fishery may draw many anglers, which may lead to enhanced risk of overfishing. Furthermore, external pressures will also affect fisheries, leading to fishery collapses despite the best intentions of management. Any management decision about regulations and habitat alteration will have effects on angler satisfaction and conservation. Decisions should be made with the intention of achieving fisheries objectives despite the uncertainties that arise from sampling data, ecosystem processes, and external factors, yet they must be defensible to stakeholders and the public. We show herein how decision analysis can be used to evaluate and communicate the relative efficacy of management decisions that are made to achieve fisheries management objectives by using a variety of commonly collected field data. We used a wild kokanee population at risk of overfishing as a case study and evaluated the medium‐term effects of fishing regulations and habitat alterations on conservation and angler utility objectives. Using a flexible age‐structured model, we determined that these two objectives are often at odds, where management actions leading to high angler utility in this fishery also lead to high conservation risk. Overall, decision analysis helps to communicate these tradeoffs and makes it clear how particular decisions were made. Decision analysis is not new, but it is often underused in recreational fisheries. This work demonstrates how it may streamline decisions, even for infrequently monitored fisheries, and lead to better fisheries overall. [ABSTRACT FROM AUTHOR]

Instream habitat degradation and loss are major threats to freshwater fishes and critical conservation issues among nongame species due to a lack of research and knowledge concerning their habitat requirements. Instream physical cover is an important component of fish habitat, especially for benthic species that require cover for reproduction and shelter from predators. One such species is the Carolina Madtom Noturus furiosus, a small, imperiled, nongame catfish that is endemic to the Neuse and Tar River basins of North Carolina. To enhance understanding of instream cover dynamics, we constructed artificial cover units from terra cotta materials and deployed them in rivers to (1) evaluate whether they could be an effective passive‐sampling technique to estimate detection and occupancy of the Carolina Madtom and (2) determine their potential to enhance habitat in systems where instream cover has been lost. Artificial cover units were deployed at eight sites in the Neuse and Tar River basins, and the units collected 30 Carolina Madtoms at two sites in the Tar River basin. Occupancy modeling estimated a Carolina Madtom detection probability of 0.92 using artificial cover units. Compared to other standardized sampling methods, artificial cover units were an efficient passive‐sampling technique for detecting Carolina Madtoms. Observations also revealed that artificial cover units were occupied by Carolina Madtoms for reproduction. These findings provide an additional means by which natural resource managers can assess the status of this imperiled species via an inexpensive passive‐sampling device that can provide spawning habitat and protection from predators as well as helping to mitigate the effects of instream habitat degradation. [ABSTRACT FROM AUTHOR]

Concerns have been raised regarding the practice of exposing fish to air during catch‐and‐release (C&R) angling. The purpose of this study was to evaluate the effects of air exposure on short‐ and long‐term survival and progeny production of Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri. Prespawn adults were sampled at a weir during upstream migration in 2016 and 2017, exposed to a simulated angling event of 102 s, and then exposed to air for a randomly selected duration of 0, 30, or 60 s. An additional control group was added during 2017 in which fish were not exposed to simulated angling or air. In total, 1,519 fish were sampled in 2016, and 744 fish were sampled in 2017. Additionally, age‐0 fish (2016: n = 2,924; 2017: n = 1,492) were collected to evaluate the effects of air exposure on the production of progeny. No effect of angling itself or of angling and air exposure was observed on short‐term (≤60 d posttreatment) or long‐term (>1 year posttreatment) survival of adults, with one exception. During 2016, fish that had been air exposed for 60 s had a statistically higher short‐term survival rate than fish that received no air exposure. Air exposure had no effect on the proportion of fish that successfully spawned. Regression analysis revealed that neither angling nor air exposure affected progeny production. Considering that much of the literature, as well as this study, reports little to no influence of air exposure on salmonid mortality or reproductive success, it seems highly unlikely that air exposure of less than 60 s during C&R angling would have negative population‐level effects. [ABSTRACT FROM AUTHOR]

Abstract: Effective conservation and management of mixed‐stock fisheries depends upon accurate stock identification of individual fish. We evaluated the utility of otolith chemical analysis as an approach to classify juvenile, premigratory steelhead Oncorhynchus mykiss collected in tributaries of Lake Michigan as either wild or hatchery origin. Two primary hypotheses proposed were that otolith chemistry can be used (1) to classify juvenile, hatchery‐origin steelhead to the correct hatchery of origin and (2) to correctly classify stream‐collected juvenile steelhead as wild or hatchery origin. Using laser‐ablation inductively coupled plasma mass spectrometry, we analyzed the concentrations of seven elements (using 25Mg, 55Mn, 65Cu, 66Zn, 88Sr, 137Ba, 208Pb) in the otoliths of juvenile steelhead collected from five hatcheries and 25 streams in the Lake Michigan basin. When discriminating among hatcheries, only 4.41% of fish misclassified to an alternate hatchery when subjected to the best random forest classification algorithm that included all elements as predictor variables. Distinct chemical signatures between fish of wild and hatchery origin supported 100% classification accuracies of known‐wild, age‐0 steelhead as wild origin for 19 of the 25 streams sampled. Misclassification of wild, age‐0, and hatchery‐origin fish, which tended to occur for streams that were located in close proximity to the hatchery, never exceeded 3.4% for a given stream. Our findings demonstrate highly successful discrimination of hatchery‐origin and wild juvenile steelhead across a broad geographic range. Applying the classification algorithms developed herein to unknown‐origin steelhead provides the ability to infer survival of year‐classes from specific hatcheries. Further, the ability to differentiate hatchery‐ and wild‐origin fish will assist in stock assessment efforts allowing for increased effectiveness of conservation and management of the species. [ABSTRACT FROM AUTHOR]

Abstract: The piscicide rotenone is an important and widely used management tool for native fish conservation; however, long‐term empirical field studies investigating potential effects on nontarget species are lacking. We tested for effects of rotenone on four native amphibian species inhabiting 10 fish‐bearing alpine lakes in northwest Montana. Visual encounter amphibian surveys were conducted for 2–4 years to establish baseline species‐specific detection frequencies prior to piscicide treatment to eradicate nonnative trout. Species diversity and detection frequencies varied considerably among lakes, presumably due to differences in the amount of emergent vegetation. Comparisons between baseline detection frequencies and those established from posttreatment surveys consistently revealed no significant changes in amphibian detection frequency, suggesting resiliency of amphibian populations to these piscicide treatments. These results may be explained by one or more of the following: (1) timing the rotenone application when many amphibians had metamorphosed beyond the gill‐breathing life stage; (2) application of rotenone at a concentration that was sublethal to amphibians; and (3) posttreatment immigration of adults from habitats not treated with rotenone. This study provides insight into the factors that contribute to amphibian population resiliency to alpine lake rotenone treatments within the context of a watershed‐scale native trout restoration program. [ABSTRACT FROM AUTHOR]

Globally, many freshwater fishes are declining in distribution and abundance, but for many species conservation measures are hindered by a limited knowledge of their ecology. Recent development of 12-mm half-duplex (HDX) passive integrated transponder (PIT) tags has broadened the potential application of this technology for studying habitat selection and migration of freshwater fishes. However, the limited read range of the smaller 12-mm PIT tags can limit their functionality in ecological studies. The present study used four migratory fish species to test the efficacy of different PIT antenna designs for detecting 12-mm HDX tags in small- and medium-sized rivers. Three types of pass-through antennae were created and coupled to either a single reader or multiplexor board. Across single-reader and multiplexor systems, the detection efficiencies for Giant KokopuGalaxias argenteus, Shortfin EelAnguilla australis, and New Zealand Longfin EelAnguilla dieffenbachiiranged between 87% and 97%. Adult Pouched LampreyGeotria australisalso had a high detection rate of 74%, even though several other migration routes existed that were unmonitored. Overall, the present study shows that with appropriate antenna design, the 12-mm HDX PIT tag can be effective for monitoring a variety of fish species. Although the antennae in the present study had a maximum width of 6.1 m, the spaced double-coil antenna design may increase efficacy of the 12-mm tag in larger rivers. Received April 27, 2017; accepted September 1, 2017 Published online October 30, 2017 [ABSTRACT FROM PUBLISHER]

BurbotLota lotain the lower Kootenai River, Idaho, have been the focus of extensive conservation efforts, particularly the release of hatchery-reared juvenile Burbot into small tributaries. The Idaho Department of Fish and Game installed a fixed PIT antenna on Deep Creek, a tributary of the Kootenai River, to evaluate movement of juvenile Burbot to the Kootenai River. Since then, approximately 12,000 juvenile Burbot have been PIT-tagged and released into Deep Creek, but few Burbot have been detected at the antenna, thus raising questions about their fate in the creek. The objectives of this study were to evaluate survival, movement, and distribution of Burbot released into Deep Creek. During 2014, 3,000 age-0, 200 age-1, 16 age-2, and 16 age-4 Burbot were released at two different locations; during 2015, 3,000 age-0 Burbot were released at six different locations (i.e., 500 fish/site). Five additional stationary PIT tag antennas were installed on Deep Creek prior to stocking in 2014. Mobile PIT tag antennas were used to survey the creek in 2015 and 2016. A Barker model in Program MARK was used to estimate survival. Stationary and mobile PIT tag antennas relocated 3,372 (56%) of the Burbot released in Deep Creek during 2014 and 2015. Eighty-eight percent of PIT tags relocated during mobile surveys were relocated within 1 km of a release location. Mobile surveys of release locations in Deep Creek suggested poor dispersal from stocking locations. Survival did not vary across years or release groups. Initial 7-month survival in Deep Creek was 0.27, and survival improved to 0.63 after the first 7 months. Although survival did not differ between years or among release groups, managers may consider releasing Burbot at lower densities across multiple locations. Received April 25, 2017; accepted September 1, 2017 Published online October 23, 2017 [ABSTRACT FROM PUBLISHER]

A segregated hatchery program promotes conservation by limiting the amount of overlap in return timing and spawning locations of hatchery- and natural-origin fish. The objective of the present study was to use radiotelemetry data collected from 2005 to 2007 to better understand the level of spatial and temporal segregation between hatchery and natural-origin steelheadOncorhynchus mykissin the Eagle Creek basin, Oregon. The analysis resulted in three key findings. First, hatchery-origin winter steelhead were unlikely to migrate into the North Fork Eagle Creek, a tributary that has historically lacked any hatchery releases or influence, suggesting a high level of segregation from the natural-origin population returning to that stream. Second, hatchery fish arrived at the lower fish ladder on Eagle Creek and at Eagle Creek National Fish Hatchery (NFH) earlier than natural-origin fish, suggesting that broodstock management practices to maintain an early returning hatchery stock (i.e., temporal segregation) have been somewhat successful. Finally, regardless of the differential arrival timing to Eagle Creek NFH, there is evidence of an increased probability of spatial and temporal overlap of the populations as the return progresses, and this may be explained by successful reproduction of hatchery-origin fish in main-stem Eagle Creek. Integrated and segregated hatchery programs should be monitored periodically to ensure that they are meeting their stated goals. Received October 12, 2016; accepted March 14, 2017 Published online May 4, 2017 [ABSTRACT FROM AUTHOR]

The Okaloosa Darter Etheostoma okaloosae is a small percid endemic to six stream drainages in northwestern Florida. The U.S. Fish and Wildlife Service listed Okaloosa Darters as endangered in 1973 and downlisted them to threatened in 2011 because of habitat improvements and increasing abundance across much of their geographic range. Delisting is possible if remaining recovery criteria are met, including restoration of degraded stream reaches. Impounded reaches of Anderson Branch, Mill Creek, and Toms Creek were restored by removing impediments to water flow, draining impoundments, and reconstructing stream reaches. Restorations of Anderson Branch and Mill Creek were designed to rehabilitate populations of Okaloosa Darters without significantly affecting popular recreational activities at these locations. Restorations were evaluated from 2007 to 2013 by comparing counts of Okaloosa Darters and the composition of microhabitats in restored and nearby undisturbed reference sites. Okaloosa Darters were absent from degraded stream reaches at the beginning of the study, but they rapidly colonized once restorations were completed. Counts of Okaloosa Darters in reference and restoration sites in Anderson Branch were similar by the end of the study, whereas counts in restoration sites were significantly lower than nearby reference sites in Mill and Toms creeks. Restoration sites tended to have lower coverage of sand and root and higher coverage of macrophytes. As riparian vegetation surrounding restoration sites matures to a closed canopy that reduces excessive growth of macrophytes, stream microhabitats and numbers of darters will probably become similar to reference sites. Restoration of degraded stream sites increased abundance and distribution of Okaloosa Darters and reconnected formerly isolated upstream and downstream populations. These projects demonstrated that restoration is a useful conservation tool for imperiled fishes such as Okaloosa Darters and can be undertaken without interfering with popular recreational activities. [ABSTRACT FROM AUTHOR]

The distributions of most native trout species in western North America have been severely reduced, and conservation of many of these species will require translocation into vacant habitats following removal of nonnative species. A critical question managers have is “Does it matter which donor sources are used for these translocations?” We present a case study that addressed this question for a large native trout translocation project in Montana. We introduced embryos from five source populations of Westslope Cutthroat TroutOncorhynchus clarkii lewisito a large, fishless watershed in Montana following removal of nonnative fish with piscicides. Source populations providing embryos for translocations were three nearby (<120 km) wild populations, the state of Montana’s captive Westslope Cutthroat Trout hatchery conservation population (initiated 32 years ago using fish from wild populations located >350 km from the translocation site), and a population in captivity for one generation comprised of individuals from the three wild populations used as single sources for this project, which were variably crossed (59% within populations and 41% between populations) to provide embryos. We used remote-site incubators at six different sites to introduce approximately 35,000 embryos from 400 genotyped parents. We later resampled and genotyped 1,450 of these individuals at age 1 and age 2. Juvenile survival for the more genetically diverse Montana Westslope Cutthroat Trout conservation population was twice as high as for other source populations, even though these other source populations were geographically closer to the translocation site than populations used to make the Montana Westslope Cutthroat Trout conservation population. Body weight for progeny from the two captive populations was higher than for progeny from wild source populations, and some differences were observed in body condition among source populations. Continued monitoring over several generations will be necessary to determine the eventual contributions of each source population and the relevance of these initial findings. Received October 9, 2015; accepted February 27, 2016 Published online July 20, 2016 [ABSTRACT FROM AUTHOR]

There is an urgent need to consider more aggressive and direct interventions for the conservation of freshwater fishes that are threatened by invasive species, habitat loss, and climate change. Conservation introduction (moving a species outside its indigenous range to other areas where conditions are predicted to be more suitable) is one type of translocation strategy that fisheries managers can use to establish new conservation populations in areas of refugia. To date, however, there are few examples of successful conservation-based introductions. Many attempts fail to establish new populations—in part because environmental factors that might influence success are inadequately evaluated before the translocation is implemented. We developed a framework to assess the feasibility of rescuing threatened fish populations through translocation into historically unoccupied stream and lake habitats. The suitability of potential introduction sites was evaluated based on four major components: the recipient habitat, recipient community, donor population, and future threats. Specific questions were then developed to evaluate each major component. The final assessment was based on a scoring system that addressed each question by using criteria developed from characteristics representative of highly suitable habitats and populations. This framework was used to evaluate the proposed within-drainage translocation of three Bull TroutSalvelinus confluentuspopulations in Glacier National Park, Montana. Our results indicated that within-drainage translocation is a feasible strategy for conserving locally adapted populations of Bull Trout through the creation of new areas of refugia in Glacier National Park. The framework provides a flexible platform that can help managers make informed decisions for moving threatened fishes into new areas of refugia for conservation and recovery programs. Received April 26, 2015; accepted January 17, 2016 Published online July 7, 2016 [ABSTRACT FROM AUTHOR]

Accurate estimates of age and growth of fishes are important in the management and conservation of species and for the development of modeling approaches. Assessments of endangered or rare species typically are limited by poor or inadequate data owing to low abundance, unrepresentative sampling, and/or restrictions on sampling. Atlantic SturgeonAcipenser oxyrinchus oxyrinchus, which occurs along the east coast of North America, has five distinct population segments (DPSs) listed under the U.S. Endangered Species Act. The New York Bight (NYB) DPS is listed as endangered and represents the largest DPS in the United States. Coastal trawl surveys from 2005 to 2012 were used to evaluate the current age structure of the NYB DPS. A total of 21 year-classes (mean age = 8.89 years,n= 742 fish) were observed. Age data for the NYB DPS were combined with other available age estimates from multiple research laboratories and sources (n= 2,774) in the Hudson River and Delaware River as well from the coastal regions of New York, New Jersey, and Delaware from 1975 to 2012. Collectively, the combined data set captured much of the age range of the species, minimizing age biases and resulting in improved von Bertalanffy parameter estimates (L∞= 278.87,K= 0.057,t0= −1.27) with high overall model fit (r2= 0.87). We assessed the effects of individual data sets through a series of leave-one-out bootstrap routines that evaluated the influence of each data set on growth parameter estimates. The parameter estimates of the von Bertalanffy growth function were influenced by sampling location and/or researcher effects. Despite these differences, the combined data set approach used here represents the most comprehensive study on the age-and-growth relationship of Atlantic Sturgeon and provides parameter estimates for the development of population dynamics models and valuable information for future management. Received February 23, 2015; accepted September 24, 2015 [ABSTRACT FROM AUTHOR]

Trait-selective mortality is of considerable management and conservation interest, especially when trends are similar across multiple species of conservation concern. In the Columbia River basin, thousands of juvenile Pacific salmonidsOncorhynchusspp. are collected each year and are tagged at juvenile bypass system (JBS) facilities located at hydroelectric dams, thus allowing the tracking of population-level performance metrics (e.g., juvenile survival and juvenile-to-adult survival). Several studies have suggested that juvenile salmonid survival is both size dependent and condition dependent, but little is known about trait-selective collection at JBS facilities. Trait-selective collection (e.g., length-based or condition-based selectivity) is particularly important, as inferences to population-level performance metrics may be biased if both the survival and collection processes are influenced by similar characteristics. We used a capture–mark–recapture study to investigate length- and condition-selective survival and detection probabilities for two salmonid species in the Columbia River basin. In 2014, juvenile steelheadO. mykiss(n= 11,201) and yearling Chinook SalmonO. tshawytscha(n= 7,943) were PIT-tagged, measured (FL), examined for external condition characteristics (descaling, body injuries, fin damage, or disease symptoms), and released into the Lower Granite Dam JBS facility on the Snake River to continue seaward migration. Results indicated similar trends in both length- and condition-selective juvenile survival and detection probabilities. For both species, survival probability was higher for longer, nondegraded individuals (those without descaling, body injuries, or fin damage). Trends in detection probability were also consistent across species: shorter, degraded individuals were more likely to be detected at downstream JBS facilities than longer, healthier individuals. These results suggest that similar characteristics (FL and external condition) affect survival and detection processes for PIT-tagged steelhead and yearling Chinook Salmon and that JBS facilities may selectively collect smaller, degraded individuals with lower probabilities of survival. The consistency in trait-selective survival and detection results has important management implications for several species of conservation concern. Received February 3, 2015; accepted July 20, 2015 [ABSTRACT FROM AUTHOR]

Salmonid ecology and conservation projects often necessitate distinguishing the offspring from anadromous or nonanadromous mothers, but the forms are often physically and genetically similar. We rearedOncorhynchus mykissfry produced by anadromous mothers on one of two diets: one rich in and the other depleted in marine nutrients. We then sampled and analyzed fin and muscle tissues from fish fed both diets for nitrogen stable isotopes over time. Tissue nitrogen values from fish on the marine-nutrient-depleted diet indicated the size and time cutoffs at which offspring of anadromousO. mykissno longer reflected a marine origin (muscle tissue cutoff: 0.81 g, 50.8 mm, and 29.4 d postfeeding; fin tissue cutoff: 0.65 g, 45.9 mm, and 35.3 d). Salmonids smaller than 50 mm cannot provide a sufficiently large fin sample for isotopic analysis without significant risk of mortality. Therefore, our experiment did not reveal a period when fish were large enough to provide a nonlethal fin clip but still maintain their maternal nitrogen isotope signature. However, fish growing slower than those we examined would likely be distinguishable for a longer period of time than our data indicated. Received December 21, 2014; accepted May 2, 2015 [ABSTRACT FROM PUBLISHER]

The Magnuson–Stevens Fishery Conservation and Management Reauthorization Act of 2006 required regional fishery management councils to implement annual catch limits (ACLs) for nearly all stocks under U.S. federal management. Since 2011, the number of stocks requiring ACLs (and monitoring) has increased nearly 10-fold, with strict accountability measures requiring either in-season quota closures or shortening of subsequent seasons to avoid ACL overages. Robust forecasts of landings can also provide a projected baseline for evaluation of proposed management alternatives. We compared generalized linear models (GLMs), generalized additive models (GAMs), and seasonal autoregressive integrated moving average (SARIMA) models in terms of fit, accuracy, and ability to forecast landings of four representative fish stocks that support recreational fisheries in the southeastern United States. All models were useful in developing reliable forecasts to inform management. The GAMs provided the best fit to the observed data; however, the modeling approaches of the SARIMA model and GLM provided the best forecasts for most scenarios. The SARIMA model and GLM also provided the best predictions of the seasonal trend in landings, a desirable feature for in-season quota monitoring. The SARIMA model was more sensitive and the GLM was less sensitive to recent trends, providing a useful “bookend” for forecasts. The time span of input data affected forecast accuracy from all model types considered. This study suggests multiple forecasting models should be investigated and performance metrics carefully selected and evaluated, as no single model is likely to perform best for all stocks of interest. Received December 18, 2014; accepted April 20, 2015 [ABSTRACT FROM PUBLISHER]

Westslope Cutthroat TroutOncorhynchus clarkii lewisiin Coeur d’Alene Lake, Idaho, have declined in recent years; predation by Northern PikeEsox lucius, a nonnative sport fish, is thought to be a causative mechanism. The goal of this study was to describe the seasonal food habits of Northern Pike and determine their influence on Westslope Cutthroat Trout in Coeur d’Alene Lake by using a bioenergetics modeling approach. Fish were sampled monthly from March 2012 to May 2013 using pulsed-DC electrofishing and experimental gillnetting in four bays. Northern Pike catch rates from electrofishing were generally low but increased slightly each season and were highest in the southern portion of the lake; catch rates from gillnetting were approximately 50% higher during the two spring sampling periods compared with the summer and fall. Seasonal growth and food habits of 695 Northern Pike (TL = 16.2–108.0 cm; weight = 24–9,628 g) were analyzed. Diets primarily consisted of kokaneeO. nerka, Westslope Cutthroat Trout, and Yellow PerchPerca flavescens. Results of a bioenergetics model estimated that Westslope Cutthroat Trout represented approximately 2–30% of the biomass consumed by age-1–4 Northern Pike. Total Westslope Cutthroat Trout biomass consumed by Northern Pike (2008–2011 year-classes) across all seasons sampled was estimated to be 1,231 kg (95% CI = 723–2,396 kg), and the total number consumed was 5,641 (95% CI = 3,311–10,979). The highest occurrence of Westslope Cutthroat Trout in Northern Pike diets was observed during spring. Thus, reducing Northern Pike predation on Westslope Cutthroat Trout would be one tool worth considering for conserving Westslope Cutthroat Trout populations in Coeur d’Alene Lake. Received March 7, 2014; accepted September 22, 2014 [ABSTRACT FROM AUTHOR]

In this article we describe the current status and conservation of interior (potamodromous) Redband TroutOncorhynchus mykisssspp. throughout its range in the western United States using extant data and expert opinion provided by fish managers. Redband Trout historically occupied 60,295 km of stream habitat and 152 natural lakes. Currently, Redband Trout occupy 25,417 km of stream habitat (42% of their historical range) and 124 lakes or reservoirs. Nonhybridized populations are assumed to occupy 11,695 km (46%) of currently occupied streams; however, fish from only 4,473 km (18%) have been genetically tested. Approximately 47% of the streams occupied by Redband Trout occur on private land, 45% on government lands, and 8% in protected areas. A total of 210 Redband Trout populations, occupying 15,252 km of stream habitat (60% of the current distribution) and 95,158 ha of lake habitat (52%), are being managed as “conservation populations.” Most conservation populations have been designated as weakly to strongly connected metapopulations (125; 60%) and occupy much more stream length (14,112 km; 93%) than isolated conservation populations (1,141 km; 7%). The primary threats to Redband Trout include invasive species, habitat degradation and fragmentation, and climate change. Although the historical distribution of interior Redband Trout has declined dramatically, we conclude that the species is not currently at imminent risk of extinction because it is still widely distributed with many populations isolated by physical barriers and active conservation efforts are occurring for many populations. However, the hybridization status of many populations has not been well quantified, and introgression may be more prevalent than documented here. We recommend (1) collecting additional genetic data and estimating distribution and abundance by means of a more rigorous spatial sampling design to reduce uncertainties, (2) collecting additional information to assess and predict the impacts of climate on populations, and (3) continuing to use this database to evaluate the status of Redband Trout and inform conservation efforts through time. Received March 21, 2014; accepted August 1, 2014 [ABSTRACT FROM AUTHOR]

The authors respond to the comments on their paper about the conservation of sockeye salmon populations and the use of the genetic stock identification approach in salmon management. They discuss the reluctance of the authors who commented on their paper to accept the idea on the application of the approach. They disagree to the opinion that the approach cannot be used as a salmon management and assessment tool to meet the conservation requirements of the Wild Salmon Policy (WSP) in Canada.

The authors comment on the findings of researcher T. D. Beacham and colleagues on the protection and management of sockeye salmon populations in the Skeena River, British Columbia. They believe that the researchers fail to emphasize the complexity of sockeye salmon populations and consider the appropriate fish population structure required for conservation in Canada. They think that the researchers overstate the use of the genetic stock identification approach in contemporary salmon management.

We validated techniques for estimating the daily age of young-of-the-year Alligator Gar,Atractosteus spatula. Alligator Gar eggs were hatched and larvae were grown in aquaria and then transferred to an outdoor artificial stream. Fish were sampled from 21 d to 118 d posthatch. Sagittal otoliths were extracted from each fish, and each otolith was embedded in a clear epoxy resin. Otoliths were sectioned along a transverse plane, sanded with 600-grit sandpaper to reveal daily rings, and then polished with 1500-grit sandpaper. We estimated the daily age of each otolith three times, making each estimate in random order without reference to known ages. The mean of the three counts for each otolith was considered the final age estimate. Daily age estimates of 50 Alligator Gar (21–118 d old, 43–458 mm total length) were closely related to known fish ages, validating daily ring deposition. Absolute error in age estimates increased after 62 d posthatch; 68% of the estimated ages were within ±3 d of the known age through 62 d, whereas only 26% of the estimated ages were within ±3 d of the known age from 76 to 118 d posthatch. However, mean estimates for each cohort were within 5 d of known age through 104 d posthatch. Daily increments near the core were difficult to identify, but later increments were more discernable and deposited in a regular pattern. A significant relationship was also identified between fish total length and otolith radius (P< 0.01), indicating that estimates of growth histories should be reliable. We encourage researchers to utilize our aging technique to estimate hatch dates, the timing and frequency of hatching, and early growth rates of Alligator Gar in wild populations. This early life history information will be valuable in enhancing management and conservation of this species. Received March 21, 2014; accepted July 16, 2014 [ABSTRACT FROM AUTHOR]

Abstract Fish, especially migratory species, are assumed to benefit from dam removals that restore connectivity and access to upstream habitat, but few studies have evaluated this assumption. Therefore, we assessed the movement of migratory fishes in the springs of 2008 through 2010 and surveyed available habitat in the Little River, North Carolina, a tributary to the Neuse River, after three complete dam removals and one partial (notched) dam removal. We tagged migratory fishes with PIT tags at a resistance-board weir located at a dam removal site (river kilometer [rkm] 3.7) and followed their movements with an array of PIT antennas. The river-wide distribution of fish following removals varied by species. For example, 24–31% of anadromous American ShadAlosa sapidissima, 45–49% of resident Gizzard ShadDorosoma cepedianum, and 4–11% of nonnative Flathead CatfishPylodictis olivarispassed the dam removal site at rkm 56 in 2009 and 2010. No preremoval data were available for comparison, but reach connectivity appeared to increase as tagged individuals passed former dam sites and certain individuals moved extensively both upstream and downstream. However, 17–28% did not pass the partially removed dam at rkm 7.9, while 20–39% of those that passed remained downstream for more than a day before migrating upstream. Gizzard Shad required the deepest water to pass this notched structure, followed by American Shad then Flathead Catfish. Fish that passed the notched dam accessed more complex habitat (e.g., available substrate size-classes) in the middle and upper reaches. The results provide strong support for efforts to restore currently inaccessible habitat through complete removal of derelict dams. Received August 23, 2013; accepted June 18, 2014 [ABSTRACT FROM AUTHOR]

Little is known about the variability in the spatial and temporal distribution of spawning potamodromous trout despite decades of research directed at salmonid spawning ecology and the increased awareness that conserving life history diversity should be a focus of management. We monitored a population of fluvial–resident Bonneville Cutthroat TroutOncorhynchus clarkii utahin a tributary to the Logan River, Utah, from 2006 to 2012 to gain insight into the distribution and timing of spawning and what factors may influence these spawning activities. We monitored Bonneville Cutthroat Trout using redd surveys with multiple observers and georeferenced redd locations. We documented an extended spawning period that lasted from late April to mid-July. The onset, median, and end of spawning was best predicted by the mean maximum water temperature during the first 13 weeks of the year (F = 130. 4, df = 5,R2= 0.96,P< 0.0001) with spawning beginning and ending earlier in years that had warmer water temperatures prior to spawning. The distribution of redds was clumped each year and the relative density of redds was greater in a reach dominated by dams constructed by beaversCastor canadensis. Both dam failure and construction appeared to be responsible for creating new spawning habitat that was quickly occupied, demonstrating rapid temporal response to local habitat changes. Bonneville Cutthroat Trout appeared to establish and defend a redd for up to 2 d, and spawning most often occurred between similar-sized individuals. Spawning surveys for potamodromous trout are an underutilized tool that could be used to better understand the distribution and timing of spawning as well as determine the size and trends of the reproducing portion of populations of management concern. Without efforts to document the diversity of this important aspect of potamodromous trout life history, prioritization of conservation will be problematic. [ABSTRACT FROM AUTHOR]

Quantifying the effectiveness of management actions to mitigate the effects of changing climatic conditions (i.e., climate adaptation) can be difficult, yet critical for conservation. We used population genetic data from 1984 to 2011 to assess the degree to which ambient climatic conditions and targeted suppression of sources of nonnative Rainbow TroutOncorhynchus mykisshave influenced the spread of introgressive hybridization in native populations of Westslope Cutthroat TroutO. clarkii lewisi. We found rapid expansion in the spatial distribution and proportion of nonnative genetic admixture in hybridized populations from 1984 to 2004, but minimal change since 2004. The spread of hybridization was negatively correlated with the number of streamflow events in May that exceeded the 75th percentile of historic flows (r= −0.98) and positively correlated with August stream temperatures (r= 0.89). Concomitantly, suppression data showed a 60% decline in catch per unit effort for fish with a high proportion of Rainbow Trout admixture, rendering some uncertainty as to the relative strength of factors controlling the spread of hybridization. Our results illustrate the importance of initiating management actions to mitigate the potential effects of climate change, even where data describing the effectiveness of such actions are initially limited but the risks are severe. Received November 22, 2013; accepted March 1, 2014 [ABSTRACT FROM AUTHOR]

We examined whether a supplementation program for steelheadOncorhynchus mykissin southwestern Washington could produce hatchery fish that contained genetic characteristics of the endemic population from which it was derived and simultaneously meet a production goal. Hatchery fish were produced for three consecutive years by using broodstock comprised of endemic juveniles that were caught in the wild and raised to maturity, and then the program transitioned to an integrated broodstock comprised of wild and hatchery adults that returned to spawn. Importantly, some auxiliary conservation-based husbandry protocols were attempted (i.e., pairwise mating between males and females) but not always completed due to insufficient broodstock and conflict between production and conservation goals. The hatchery met production goals in 6 of 9 years, but wild-type genetic integrity of hatchery fish was degraded every year. Specifically, we analyzed 10 microsatellites and observed a 60% reduction in the effective number of breeders in the hatchery (harmonic mean of hatchery,Nb= 45, compared with the wild,Nb= 111). Hatchery fish consequently displayed reduced genetic diversity and large temporal genetic divergence compared with wild counterparts. To ensure the benefit of conservation-based husbandry, spawning protocols should be based on scientific theory and be practical within the physical and biological constraints of the system. Finally, if conservation issues are considered to be the most important issue for hatchery propagation, then production goals may need to be forfeited. Received November 8, 2013; accepted February 19, 2014 [ABSTRACT FROM AUTHOR]

Primary data (size and age structure, abundance) and derived data (growth, mortality, recruitment) were used to assess the status and trends of Bull TroutSalvelinus confluentusin the North Fork of the Clearwater River, Idaho, under a 14-year harvest closure. From 2000 (6 years after harvest closure) to 2008, an increase in the number of larger and older migratory Bull Trout occurred, as evidenced by the rightward shift in the cumulative length-frequency distribution, increases in mean total length and weight, and increases in age. The stability in growth rates over an 8-year interval indicated that the increases in size structure were age related (e.g., recruitment and mortality changes) rather than growth related. The abundance of migratory spawning adults also steadily increased over the period 1994–2008, as indicated by the increases in redd counts. A logistic model fitted to population estimates (not including unsampled portions of the drainage where migratory Bull Trout are known to exist) indicated that the rate of population growth as of 2005 was beginning to slow and that a carrying capacity of 5,215 total migratory adults will be asymptotically approached, surpassing the U.S. Fish and Wildlife Service's drainage-wide recovery goal of 5,000 total adults. The results from an age-structured population model (model 1) indicated a carrying capacity (5,716 migratory adults) similar to that of the logistic model. If the results under model 1 are achieved, the migratory adult population (including nonspawning adults) will surpass 5,000 adults in 2019. The results under a second model depicted a lower carrying capacity (3,592 fish). This analytical approach has promise for application in situations where harvest restrictions or the elimination of fishing are part of Bull Trout restoration programs. Received August 8, 2013; accepted December 11, 2013 [ABSTRACT FROM AUTHOR]

Traveling water screens (TWSs) modified for fish protection can be used at power plant cooling water intakes to reduce the injury to and mortality of impinged fish. Existing biological efficacy data show that postimpingement survival is highly variable by species and has improved over time as screen designs have incorporated more fish-friendly features. Data with the improved screen designs were largely absent for many freshwater species prior to this evaluation. The mortality, injury, and scale loss rates of 10 species of freshwater fish impinged and recovered with a modified Ristroph-style TWS were evaluated in a laboratory flume. Fish were impinged at a 0.3-, 0.6-, or 0.9-m/s approach velocity. Over 13,000 fish were tested in more than 100 replicates during the study. Mortality rates did not exceed 5% for any species and velocity tested. Despite a general trend toward increasing mortality at higher velocities, velocity was only a significant factor in the mortality of BluegillsLepomis macrochirus. Injury and scale loss rates were low for most of the species tested, although they were more variable than the observed rates of mortality. There was a trend toward lower mortality, injury, and scale loss in larger fish. In all cases in which fish length was a significant factor, the pattern of decreasing mortality, injury, and scale loss as fish increased in length was consistently observed. These results indicate that TWSs modified for fish protection have the potential to prevent impingement losses at power plant intakes. Received June 28, 2013; accepted October 25, 2013 [ABSTRACT FROM AUTHOR]

Fish recruitment can be influenced by the direct effects of and interactions among biological, environmental, and anthropogenic factors. However, interpretation of data that quantify associations between recruitment during early ontogenetic stages and potential underlying causal factors at whole-population scales can be confounded by the uncertainties associated with data collection. For nest-building species, biases may result from observational methods used to locate nests and determine nest-specific offspring survival. Such biases may hinder efforts to associate estimates of individual reproductive success or failure with recruitment variation at the population level. During spring 2010, Largemouth BassMicropterus salmoidesnests in a 24-ha Michigan lake were surveyed using established observational methods, and genetic data and pedigree reconstruction were used to assess the reliability of those methods. We georeferenced observed nests, visually assessed whether eggs from nests survived to the swim-up fry stage, and collected offspring from each observed nest for multilocus genotyping to characterize nest-specific pedigrees. In late summer, we captured age-0 Largemouth Bass for genotyping and used pedigree reconstruction to determine their nests of origin. Comparisons of genetic pedigree and observational data revealed that genetic methods offered a novel, powerful way of evaluating nest observation procedures. We estimated that 50% of the nests that contributed age-0 recruits were not observed by field crews; 40% of observed nests that produced late-summer age-0 Largemouth Bass (as determined based on genetic data) were not observed to produce swim-up fry during the nesting period (i.e., were misclassified as having failed). Our analyses suggest that nesting observations underestimate nest abundance and incorrectly classify some nests as having failed to produce swim-up fry, thus potentially creating a biased representation of nest-specific contributions to recruitment. Received March 26, 2013; accepted October 17, 2013 [ABSTRACT FROM AUTHOR]

Thermal tolerances have been studied for individual fish species but few have investigated how stream fish assemblages respond along a temperature gradient and which thermal ranges act as a threshold, triggering discernible community change. The purpose of this study was to define summer temperature thresholds of fish community transitions in Connecticut streams. The program Threshold Indicator Taxa Analysis suggested that the coldwater class had a June–August mean water temperature < 18.29°C, the coolwater class 18.29–21.70°C, and a warmwater class > 21.70°C. Significant indicator species of coldwater streams were Slimy SculpinCottus cognatusand Brook TroutSalvelinus fontinalis.Significant indicator species of warmwater streams were Cutlip MinnowExoglossum maxillingua, Smallmouth BassMicropterus dolomieu, Rock BassAmbloplites rupestris, Brown BullheadAmeiurus nebulosus, Redbreast SunfishLepomis auritusand Yellow BullheadA. natalis. The narrow 3.41°C temperature range between the coldwater and warmwater thresholds was designated as a coolwater transition zone, with potential for the presence of both coldwater and warmwater species and lack of species uniquely associated with this thermal range. Our approach based on a robust set of water temperature and fish community data should be applicable to other temperate regions and will be useful for informing development of thermal criteria, application of multimetric indices, and planning for anticipated effects of climate change. Received July 2, 2013; accepted October 8, 2013 [ABSTRACT FROM AUTHOR]

In 2004, the Pennsylvania Fish and Boat Commission implemented catch-and-release (CR) regulations on headwater stream systems to determine if eliminating angler harvest would result in an increase in the number of adult (≥100 mm) or large (≥175 mm) Brook TroutSalvelinus fontinalis. Under the CR regulations, angling was permitted on a year-round basis, no Brook Trout could be harvested at any time, and there were no tackle restrictions. A before-after–control-impact design was used to evaluate the experimental regulations. Brook Trout populations were monitored in 16 treatment (CR regulations) and 7 control streams (statewide regulations) using backpack electrofishing gear periodically for up to 15 years (from 1990 to 2003 or 2004) before the implementation of the CR regulations and over a 7–8-year period (from 2004 or 2005 to 2011) after implementation. We used Poisson mixed models to evaluate whether electrofishing catch per effort (CPE; catch/100 m2) of adult (≥100 mm) or large (≥175 mm) Brook Trout increased in treatment streams as a result of implementing CR regulations. Brook Trout CPE varied among sites and among years, and there was no significant effect (increase or decrease) of CR regulations on the CPE of adult or large Brook Trout. Results of our evaluation suggest that CR regulations were not effective at improving the CPE of adult or large Brook Trout in Pennsylvania streams. Low angler use, high voluntary catch and release, and slow growth rates in infertile headwater streams are likely the primary reasons for the lack of response. Received June 14, 2013; accepted August 28, 2013 [ABSTRACT FROM AUTHOR]