Carey T. Knight, Graham F. Montague, Daniel E. Shoup
ObjectiveYellow Perch Perca flavescens are popular sport fish; however, obtaining adequate length data can be problematic during low‐abundance years. Using fish from the sport fishery cleaning stations provides a possible source of data, but fish from this source have already been filleted, making length data questionable, and may not have intact backbones, so lengths cannot be determined. Therefore, we tested if Yellow Perch total length measured from filleted fish are similar to the total length measured before filleting and we also developed regression equations to predict total length from filleted fish length, head length, or mandible lengths and compared their accuracy to known total lengths.MethodsYellow Perch were collected from the Ohio Department of Natural Resources standardized bottom trawl survey. Each fish was measured for total length using a measuring board, and head and mandible lengths were measured with digital calipers. A subset of fish (N = 46) was filleted, and total length was again measured to see if filleting altered length measurements. We used linear regression with 10‐fold cross validation to estimate the total length of Yellow Perch from filleted fish length, head length, and mandible length.ResultOur results show that all three measurements were good predictors (R2 > 0.98) of fish total length, with precision being greatest for filleted length, followed by head length (mandible length had notably lower precision). Filleted fish lengths were significantly longer than intact total length, but we provide a regression equation that can be used to estimate unfilleted length using filleted fish length.ConclusionWe recommend estimating total length from filleted length regression or head length regression in cases when total length cannot be directly measured. Our mandible length regression can also be used, but it was slightly less precise than the head length regression, which should be used instead when practical.
{"title":"Yellow Perch length estimated from filleted, head, and mandible length measurements","authors":"Carey T. Knight, Graham F. Montague, Daniel E. Shoup","doi":"10.1002/nafm.11023","DOIUrl":"https://doi.org/10.1002/nafm.11023","url":null,"abstract":"ObjectiveYellow Perch <jats:italic>Perca flavescens</jats:italic> are popular sport fish; however, obtaining adequate length data can be problematic during low‐abundance years. Using fish from the sport fishery cleaning stations provides a possible source of data, but fish from this source have already been filleted, making length data questionable, and may not have intact backbones, so lengths cannot be determined. Therefore, we tested if Yellow Perch total length measured from filleted fish are similar to the total length measured before filleting and we also developed regression equations to predict total length from filleted fish length, head length, or mandible lengths and compared their accuracy to known total lengths.MethodsYellow Perch were collected from the Ohio Department of Natural Resources standardized bottom trawl survey. Each fish was measured for total length using a measuring board, and head and mandible lengths were measured with digital calipers. A subset of fish (<jats:italic>N</jats:italic> = 46) was filleted, and total length was again measured to see if filleting altered length measurements. We used linear regression with 10‐fold cross validation to estimate the total length of Yellow Perch from filleted fish length, head length, and mandible length.ResultOur results show that all three measurements were good predictors (<jats:italic>R</jats:italic><jats:sup>2</jats:sup> > 0.98) of fish total length, with precision being greatest for filleted length, followed by head length (mandible length had notably lower precision). Filleted fish lengths were significantly longer than intact total length, but we provide a regression equation that can be used to estimate unfilleted length using filleted fish length.ConclusionWe recommend estimating total length from filleted length regression or head length regression in cases when total length cannot be directly measured. Our mandible length regression can also be used, but it was slightly less precise than the head length regression, which should be used instead when practical.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":"328 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141613701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
John S. Hargrove, Matthew R. Campbell, Kelly Gunnell, Brett High, Clark Johnson, Patrick A. Kennedy, Janet L. Loxterman, Margaret B. Ptacek, Steven M. Seiler, Ernest R. Keeley
ObjectiveHybridization between native and nonnative fishes represents a global threat to biodiversity. Understanding how hybridization changes in response to management actions is critical to evaluating the efficacy of conservation efforts.MethodsWe quantified changes in levels of hybridization between Yellowstone Cutthroat Trout Oncorhynchus virginalis bouvieri and Rainbow Trout Oncorhynchus mykiss in the South Fork Snake River watershed, where a multipronged approach has been implemented to protect the evolutionary distinctiveness of one of the last remaining large‐river populations of Yellowstone Cutthroat Trout.ResultOver a 20‐year period, we observed an increase in the number of sample reaches without hybrids in the South Fork Snake River watershed; however, contrasting patterns were noted in main‐stem and tributary reaches. Through time, hybrid abundance increased at main‐stem reaches of the South Fork Snake River below Palisades Dam but decreased in tributaries. Efforts to reduce hybridization in spawning tributaries, including both suppression and selective passage weirs, were effective at preventing the expansion of hybridization in resident and migratory populations. Multimodel inference was used to understand factors affecting levels of hybridization, and year, sampling reach, and the interaction thereof was identified as the best‐fit model but explained only a small percentage of the overall variation, suggesting that other factors not captured in our model were driving patterns in hybridization.ConclusionChanges in hybridization in the South Fork Snake River watershed are likely the result of multiple processes, namely management actions to reduce Rainbow Trout and hybrids in tributaries, as well as demographic changes in Rainbow Trout in the main‐stem river below Palisades Dam. Our results suggest that Yellowstone Cutthroat Trout populations in the South Fork Snake River watershed have not experienced widespread interspecific hybridization with Rainbow Trout but that proactive management will be necessary to ensure long‐term conservation.
{"title":"Interspecific hybridization in a large‐river population of Yellowstone Cutthroat Trout: A 20‐year programmatic evaluation","authors":"John S. Hargrove, Matthew R. Campbell, Kelly Gunnell, Brett High, Clark Johnson, Patrick A. Kennedy, Janet L. Loxterman, Margaret B. Ptacek, Steven M. Seiler, Ernest R. Keeley","doi":"10.1002/nafm.11014","DOIUrl":"https://doi.org/10.1002/nafm.11014","url":null,"abstract":"ObjectiveHybridization between native and nonnative fishes represents a global threat to biodiversity. Understanding how hybridization changes in response to management actions is critical to evaluating the efficacy of conservation efforts.MethodsWe quantified changes in levels of hybridization between Yellowstone Cutthroat Trout <jats:italic>Oncorhynchus virginalis bouvieri</jats:italic> and Rainbow Trout <jats:italic>Oncorhynchus mykiss</jats:italic> in the South Fork Snake River watershed, where a multipronged approach has been implemented to protect the evolutionary distinctiveness of one of the last remaining large‐river populations of Yellowstone Cutthroat Trout.ResultOver a 20‐year period, we observed an increase in the number of sample reaches without hybrids in the South Fork Snake River watershed; however, contrasting patterns were noted in main‐stem and tributary reaches. Through time, hybrid abundance increased at main‐stem reaches of the South Fork Snake River below Palisades Dam but decreased in tributaries. Efforts to reduce hybridization in spawning tributaries, including both suppression and selective passage weirs, were effective at preventing the expansion of hybridization in resident and migratory populations. Multimodel inference was used to understand factors affecting levels of hybridization, and year, sampling reach, and the interaction thereof was identified as the best‐fit model but explained only a small percentage of the overall variation, suggesting that other factors not captured in our model were driving patterns in hybridization.ConclusionChanges in hybridization in the South Fork Snake River watershed are likely the result of multiple processes, namely management actions to reduce Rainbow Trout and hybrids in tributaries, as well as demographic changes in Rainbow Trout in the main‐stem river below Palisades Dam. Our results suggest that Yellowstone Cutthroat Trout populations in the South Fork Snake River watershed have not experienced widespread interspecific hybridization with Rainbow Trout but that proactive management will be necessary to ensure long‐term conservation.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":"42 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141613700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ryan E. Brown, Christine M. Mayer, Nathan Thompson, Corbin D. Hilling, James J. Roberts, Catherine A. Richter
ObjectiveBiodiversity is declining due to invasive species and other factors that can affect individual species differently. Silver Chub Macrhybopsis storeriana are declining in their native range, and their conservation status in the Great Lakes ranges from secure to possibly extirpated. Lake Erie once supported a large Silver Chub population until it crashed in the 1950s. Additionally, the spawning behavior and reproductive guild of Silver Chub in Lake Erie is unknown. Our objective was to document Silver Chub spawning in the Maumee River, a Lake Erie tributary.MethodsInvasive Grass Carp Ctenopharyngodon idella are known to spawn in the Maumee River during high‐flow events from May to July, and the University of Toledo and U.S. Geological Survey regularly sample the lower 24 km for early life stages using paired bongo nets. Contents from paired bongo nets are returned to the laboratory for processing, and a subset of potential Grass Carp eggs are sent for genetic analysis.ResultOn June 8, 2022, several potential Grass Carp eggs were captured at two sites on the Maumee River during a high‐flow event. Fifteen potential Grass Carp eggs were sent for genetic analysis, and DNA sequencing revealed that six of these eggs were Silver Chub.DiscussionThis was the first known collection of Silver Chub eggs in a Lake Erie tributary, and our findings indicate that Silver Chub likely belong to the pelagophil reproductive guild. Although Grass Carp and Silver Chub spawn under similar conditions, management actions to control Grass Carp in the Maumee River may be unlikely to affect Silver Chub due to electrofishing settings used in the capture of Grass Carp. The verification of Silver Chub spawning in a Western Erie Basin tributary provides insights into their reproductive biology that could be useful in recovery planning in Lake Erie and throughout the Great Lakes.
{"title":"Silver Chub spawning confirmed in the Maumee River, a tributary of Lake Erie","authors":"Ryan E. Brown, Christine M. Mayer, Nathan Thompson, Corbin D. Hilling, James J. Roberts, Catherine A. Richter","doi":"10.1002/nafm.11018","DOIUrl":"https://doi.org/10.1002/nafm.11018","url":null,"abstract":"ObjectiveBiodiversity is declining due to invasive species and other factors that can affect individual species differently. Silver Chub <jats:italic>Macrhybopsis storeriana</jats:italic> are declining in their native range, and their conservation status in the Great Lakes ranges from secure to possibly extirpated. Lake Erie once supported a large Silver Chub population until it crashed in the 1950s. Additionally, the spawning behavior and reproductive guild of Silver Chub in Lake Erie is unknown. Our objective was to document Silver Chub spawning in the Maumee River, a Lake Erie tributary.MethodsInvasive Grass Carp <jats:italic>Ctenopharyngodon idella</jats:italic> are known to spawn in the Maumee River during high‐flow events from May to July, and the University of Toledo and U.S. Geological Survey regularly sample the lower 24 km for early life stages using paired bongo nets. Contents from paired bongo nets are returned to the laboratory for processing, and a subset of potential Grass Carp eggs are sent for genetic analysis.ResultOn June 8, 2022, several potential Grass Carp eggs were captured at two sites on the Maumee River during a high‐flow event. Fifteen potential Grass Carp eggs were sent for genetic analysis, and DNA sequencing revealed that six of these eggs were Silver Chub.DiscussionThis was the first known collection of Silver Chub eggs in a Lake Erie tributary, and our findings indicate that Silver Chub likely belong to the pelagophil reproductive guild. Although Grass Carp and Silver Chub spawn under similar conditions, management actions to control Grass Carp in the Maumee River may be unlikely to affect Silver Chub due to electrofishing settings used in the capture of Grass Carp. The verification of Silver Chub spawning in a Western Erie Basin tributary provides insights into their reproductive biology that could be useful in recovery planning in Lake Erie and throughout the Great Lakes.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":"57 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141613703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Donald M. Van Doornik, Paul Moran, Eric B. Rondeau, Krista M. Nichols, Shawn R. Narum, Matthew R. Campbell, Anthony J. Clemento, John S. Hargrove, Jon E. Hess, Rebekah L. Horn, Lisa W. Seeb, Jeff J. Stephenson, Garrett J. McKinney
ObjectiveGenetic stock identification (GSI) can be an effective tool for fisheries management, but development of reference baselines for species with broad geographic distributions can be challenging. Mixed‐stock fisheries for Chinook Salmon Oncorhynchus tshawytscha have utilized GSI analyses for decades with various genetic baselines, but these have largely become outdated with advances in technology that enable more efficient genotyping. Thus, our goals were to (1) create nested baselines of genotypic data for Chinook Salmon throughout their entire natural range using existing data from multiple sources and (2) evaluate the utility of those nested baselines to conduct accurate hierarchical GSI of mixture proportions or the stock identification of individual fish.MethodsIn this study, we compiled a large genetic baseline of single‐nucleotide polymorphism (SNP) markers for 389 populations that encompass the entire geographic range of Chinook Salmon. We used cross validation and realistic mixture simulations to test the accuracy of the baseline in generating GSI estimates.ResultWe demonstrated that a multi‐tiered assignment approach can provide high accuracy at both tier 1 (broadscale, with three coastwide reporting groups; 97.8% mean accuracy) and tier 2 (fine‐scale regional reporting groups; up to 97.7% mean accuracy) levels. Realistic mixture simulations showed that this multi‐tiered approach can provide highly effective GSI results for several common mixed‐stock fisheries applications in the Pacific Ocean.ConclusionThis new SNP baseline and the multi‐tiered assignment approach provide the most comprehensive rangewide GSI baseline for Chinook Salmon over any previous application and enable highly accurate estimates for GSI purposes.
{"title":"A new, standardized international Pacific Rim baseline for genetic stock identification (GSI) of Chinook Salmon","authors":"Donald M. Van Doornik, Paul Moran, Eric B. Rondeau, Krista M. Nichols, Shawn R. Narum, Matthew R. Campbell, Anthony J. Clemento, John S. Hargrove, Jon E. Hess, Rebekah L. Horn, Lisa W. Seeb, Jeff J. Stephenson, Garrett J. McKinney","doi":"10.1002/nafm.11019","DOIUrl":"https://doi.org/10.1002/nafm.11019","url":null,"abstract":"ObjectiveGenetic stock identification (GSI) can be an effective tool for fisheries management, but development of reference baselines for species with broad geographic distributions can be challenging. Mixed‐stock fisheries for Chinook Salmon <jats:italic>Oncorhynchus tshawytscha</jats:italic> have utilized GSI analyses for decades with various genetic baselines, but these have largely become outdated with advances in technology that enable more efficient genotyping. Thus, our goals were to (1) create nested baselines of genotypic data for Chinook Salmon throughout their entire natural range using existing data from multiple sources and (2) evaluate the utility of those nested baselines to conduct accurate hierarchical GSI of mixture proportions or the stock identification of individual fish.MethodsIn this study, we compiled a large genetic baseline of single‐nucleotide polymorphism (SNP) markers for 389 populations that encompass the entire geographic range of Chinook Salmon. We used cross validation and realistic mixture simulations to test the accuracy of the baseline in generating GSI estimates.ResultWe demonstrated that a multi‐tiered assignment approach can provide high accuracy at both tier 1 (broadscale, with three coastwide reporting groups; 97.8% mean accuracy) and tier 2 (fine‐scale regional reporting groups; up to 97.7% mean accuracy) levels. Realistic mixture simulations showed that this multi‐tiered approach can provide highly effective GSI results for several common mixed‐stock fisheries applications in the Pacific Ocean.ConclusionThis new SNP baseline and the multi‐tiered assignment approach provide the most comprehensive rangewide GSI baseline for Chinook Salmon over any previous application and enable highly accurate estimates for GSI purposes.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":"3 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141573300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Felix Eissenhauer, Malik Martin, Joke Adesola, R. Allen Curry, Tommi Linnansaari, Philip M. Harrison
ObjectiveVisible implant elastomer (VIE) tags are commonly used as a cost‐effective tool for marking small fish, making them valuable in mark–recapture studies. It is crucial to quantify the impact of tagging procedures on fish survival to address inferential bias in mark–recapture studies. We assessed marking‐related mortality and growth in American Eel Anguilla rostrata elvers in a 40‐day laboratory experiment, following VIE tag application.MethodsThere were 500 elvers (80–149 mm) that were divided into four treatment groups and one control group. Treatment groups were tagged with two tags in three body locations (anterior, central, posterior on left bilateral side) or with two tags in all three locations, while the control group remained untagged. Eels were retained in experimental tanks, and mortality rates were compared.ResultThe VIE tagging did not significantly affect survival, which was 90.9% across all treatment groups and 92% for the untagged control group; nor did it affect growth.ConclusionThe application of VIE tags on various body parts should be a safe and effective method for marking American Eel elvers.
目标可视植入弹性体（VIE）标签通常作为一种经济有效的工具用于标记小型鱼类，使其在标记重捕研究中具有重要价值。量化标记程序对鱼类存活率的影响对于解决标记再捕获研究中的推断偏差至关重要。我们在一项为期 40 天的实验室实验中评估了美洲鳗鲡（Anguilla rostrata elvers）在使用 VIE 标签后与标记相关的死亡率和生长情况。处理组在身体的三个位置（前部、中部、左侧后部）贴两个标签，或在所有三个位置贴两个标签，而对照组则不贴标签。在鳗鱼身体的不同部位贴上 VIE 标签应该是一种安全有效的标记美洲鳗鲡的方法。
{"title":"Short‐term survival and growth of American Eel elvers marked with visible implant elastomer tags","authors":"Felix Eissenhauer, Malik Martin, Joke Adesola, R. Allen Curry, Tommi Linnansaari, Philip M. Harrison","doi":"10.1002/nafm.11016","DOIUrl":"https://doi.org/10.1002/nafm.11016","url":null,"abstract":"ObjectiveVisible implant elastomer (VIE) tags are commonly used as a cost‐effective tool for marking small fish, making them valuable in mark–recapture studies. It is crucial to quantify the impact of tagging procedures on fish survival to address inferential bias in mark–recapture studies. We assessed marking‐related mortality and growth in American Eel <jats:italic>Anguilla rostrata</jats:italic> elvers in a 40‐day laboratory experiment, following VIE tag application.MethodsThere were 500 elvers (80–149 mm) that were divided into four treatment groups and one control group. Treatment groups were tagged with two tags in three body locations (anterior, central, posterior on left bilateral side) or with two tags in all three locations, while the control group remained untagged. Eels were retained in experimental tanks, and mortality rates were compared.ResultThe VIE tagging did not significantly affect survival, which was 90.9% across all treatment groups and 92% for the untagged control group; nor did it affect growth.ConclusionThe application of VIE tags on various body parts should be a safe and effective method for marking American Eel elvers.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":"12 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141573301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ObjectiveLow survival of emigrating salmonid smolts through the interior regions of California's Sacramento–San Joaquin River Delta (hereafter, “Delta”) and large‐scale water extraction from that region have prompted managers to seek to predict and manipulate smolt route use through the tidal Delta. The local flow variables previously used in modeling are not the metrics used in management. Here, I investigate the predictive utility of variables representing both localized flow conditions and remote management metrics to predict routing of juvenile steelhead Oncorhynchus mykiss at two river junctions on the San Joaquin River in the south Delta.MethodsIndividual‐based generalized linear models were used with detections of over 4000 acoustic‐tagged juvenile hatchery‐reared steelhead to relate routing to the presence of a rock barrier, simulated localized flow conditions from a hydrodynamic model, and daily management metrics, including upstream river discharge and water pumping rates elsewhere in the Delta. Models were developed for the first two diffluences encountered by smolts entering the Delta (head of Old River and Turner Cut).ResultExclusive use of the management metrics in routing models underestimated the subdaily, tidally dominated fluctuations in fish routing compared to localized flow covariates. The daily rate of water extraction 20–30 km away contributed to use of non‐main‐stem routes, but the effect was small compared to subhourly flow conditions at the river junctions themselves.ConclusionWater resource and fish managers are advised to monitor conditions at the locations of interest rather than depending solely on remote metrics. In the Delta, use of a flow barrier and reduction of water pumping operations when smolts are migrating should be combined with habitat improvement in interior Delta regions to optimize migratory survival through this complex and heavily modified system.
{"title":"Route use of emigrating steelhead in a heavily modified river delta","authors":"Rebecca A. Buchanan","doi":"10.1002/nafm.11005","DOIUrl":"https://doi.org/10.1002/nafm.11005","url":null,"abstract":"ObjectiveLow survival of emigrating salmonid smolts through the interior regions of California's Sacramento–San Joaquin River Delta (hereafter, “Delta”) and large‐scale water extraction from that region have prompted managers to seek to predict and manipulate smolt route use through the tidal Delta. The local flow variables previously used in modeling are not the metrics used in management. Here, I investigate the predictive utility of variables representing both localized flow conditions and remote management metrics to predict routing of juvenile steelhead <jats:italic>Oncorhynchus mykiss</jats:italic> at two river junctions on the San Joaquin River in the south Delta.MethodsIndividual‐based generalized linear models were used with detections of over 4000 acoustic‐tagged juvenile hatchery‐reared steelhead to relate routing to the presence of a rock barrier, simulated localized flow conditions from a hydrodynamic model, and daily management metrics, including upstream river discharge and water pumping rates elsewhere in the Delta. Models were developed for the first two diffluences encountered by smolts entering the Delta (head of Old River and Turner Cut).ResultExclusive use of the management metrics in routing models underestimated the subdaily, tidally dominated fluctuations in fish routing compared to localized flow covariates. The daily rate of water extraction 20–30 km away contributed to use of non‐main‐stem routes, but the effect was small compared to subhourly flow conditions at the river junctions themselves.ConclusionWater resource and fish managers are advised to monitor conditions at the locations of interest rather than depending solely on remote metrics. In the Delta, use of a flow barrier and reduction of water pumping operations when smolts are migrating should be combined with habitat improvement in interior Delta regions to optimize migratory survival through this complex and heavily modified system.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":"18 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141509122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shawn P. Sitar, Michael J. Seider, Mark P. Ebener, Stephen C. Chong, Cory A. Goldsworthy, Ian Harding, S. Ben Michaels, Seth A. Moore, Thomas Pratt, Bradley A. Ray
ObjectiveThis purpose of this paper is to describe the characteristics of recovered Lake Trout Salvelinus namaycush populations in Lake Superior by describing its population dynamics, ecology, and recent research and management activities since 1993, when Lake Trout were declared rehabilitated.MethodsData from commercial fisheries, recreational fisheries, agency stocking reports, and natural resource agency fishery‐independent survey data along with published research findings on lean Lake Trout in Lake Superior between 1993 and 2022 were synthesized and reported.ResultCurrently, Lake Trout populations are self‐sustaining and lightly exploited with only a few areas with elevated total mortality rates. The total annual mortality has been far below the target maximum range of 42–45%. Furthermore, stocking of hatchery Lake Trout is no longer necessary.ConclusionWe have learned from research and management experience that the regulatory role of Lake Trout in the Great Lakes is critical to proper ecosystem function. Thus, continued commitment from natural resource agencies to cooperate and implement effective management actions is required to preserve the accomplishments of lakewide recovery of Lake Trout populations.
{"title":"Synthesis of recent research and attributes of recovered lean Lake Trout populations in Lake Superior, 1993–2022","authors":"Shawn P. Sitar, Michael J. Seider, Mark P. Ebener, Stephen C. Chong, Cory A. Goldsworthy, Ian Harding, S. Ben Michaels, Seth A. Moore, Thomas Pratt, Bradley A. Ray","doi":"10.1002/nafm.11007","DOIUrl":"https://doi.org/10.1002/nafm.11007","url":null,"abstract":"ObjectiveThis purpose of this paper is to describe the characteristics of recovered Lake Trout <jats:italic>Salvelinus namaycush</jats:italic> populations in Lake Superior by describing its population dynamics, ecology, and recent research and management activities since 1993, when Lake Trout were declared rehabilitated.MethodsData from commercial fisheries, recreational fisheries, agency stocking reports, and natural resource agency fishery‐independent survey data along with published research findings on lean Lake Trout in Lake Superior between 1993 and 2022 were synthesized and reported.ResultCurrently, Lake Trout populations are self‐sustaining and lightly exploited with only a few areas with elevated total mortality rates. The total annual mortality has been far below the target maximum range of 42–45%. Furthermore, stocking of hatchery Lake Trout is no longer necessary.ConclusionWe have learned from research and management experience that the regulatory role of Lake Trout in the Great Lakes is critical to proper ecosystem function. Thus, continued commitment from natural resource agencies to cooperate and implement effective management actions is required to preserve the accomplishments of lakewide recovery of Lake Trout populations.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":"97 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141509123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. J. Rudershausen, J. A. Buckel, R. Gregory, G. R. Stilson, A. W. Dukes, E. L. Gooding, B. J. Runde
ObjectiveOur objective was to use sportfishing tournament data to determine whether sizes of Dolphinfish Coryphaena hippurus have been changing in the western North Atlantic (WNA) over recent decades.MethodsWe sampled North Carolina, South Carolina, and Florida marine sportfishing tournament landings for Dolphinfish lengths. Linear models were separately fitted to length data for males and females by regressing length against year. A subset of these models (analysis of covariance) considered tournament as a factor.ResultAn analysis of covariance model with a separate regression slope for each tournament provided the best fit to the data for male and female Dolphinfish. Meaningful temporal declines in the length of males and females were found for four of the five tournaments (no changes in length were observed for the fifth tournament). Median total length declines of 168, 105, 103, and 426 mm were predicted for males, and declines of 354, 133, 131, and 246 mm were predicted for females. Declines in the largest observed sizes of Dolphinfish (97.5% confidence limit) were found for most tournament‐ and sex‐specific combinations of data and could suggest excess fishing mortality on the population.ConclusionDeclines in Dolphinfish size in the WNA region could have ramifications for conservation of the population given that these size changes translate into reduced individual fecundity of female Dolphinfish. Causes of the size decline could be fishing effects, environmental effects, or a combination of these. Reductions in individual size may be occurring simultaneously with declines in abundance identified in other recent research using fishery‐dependent data collected in the WNA.
{"title":"Temporal changes in lengths of Dolphinfish revealed by sampling at sportfishing tournaments in the southeastern United States","authors":"P. J. Rudershausen, J. A. Buckel, R. Gregory, G. R. Stilson, A. W. Dukes, E. L. Gooding, B. J. Runde","doi":"10.1002/nafm.11006","DOIUrl":"https://doi.org/10.1002/nafm.11006","url":null,"abstract":"ObjectiveOur objective was to use sportfishing tournament data to determine whether sizes of Dolphinfish <jats:italic>Coryphaena hippurus</jats:italic> have been changing in the western North Atlantic (WNA) over recent decades.MethodsWe sampled North Carolina, South Carolina, and Florida marine sportfishing tournament landings for Dolphinfish lengths. Linear models were separately fitted to length data for males and females by regressing length against year. A subset of these models (analysis of covariance) considered tournament as a factor.ResultAn analysis of covariance model with a separate regression slope for each tournament provided the best fit to the data for male and female Dolphinfish. Meaningful temporal declines in the length of males and females were found for four of the five tournaments (no changes in length were observed for the fifth tournament). Median total length declines of 168, 105, 103, and 426 mm were predicted for males, and declines of 354, 133, 131, and 246 mm were predicted for females. Declines in the largest observed sizes of Dolphinfish (97.5% confidence limit) were found for most tournament‐ and sex‐specific combinations of data and could suggest excess fishing mortality on the population.ConclusionDeclines in Dolphinfish size in the WNA region could have ramifications for conservation of the population given that these size changes translate into reduced individual fecundity of female Dolphinfish. Causes of the size decline could be fishing effects, environmental effects, or a combination of these. Reductions in individual size may be occurring simultaneously with declines in abundance identified in other recent research using fishery‐dependent data collected in the WNA.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":"95 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141197932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kyle Olivencia, Emily E. Grausgruber, Mark J. Fincel, Michael J. Weber
ObjectiveWalleye Sander vitreus are important sport fish that are commonly stocked to supplement populations. Increases in Smallmouth Bass Micropterus dolomieu abundance have prompted concerns regarding potential predation by these and other piscivores on stocked Walleye. Our objectives were to assess the timing and duration of predation on stocked Walleye, the frequency of occurrence and percent composition of Walleye in predator diets, and the percentage of stocked Walleye consumed.MethodsWe collected Smallmouth Bass, adult Walleye, Largemouth Bass M. nigricans, and Northern Pike Esox lucius diets in May (prestocking) and June–September (poststocking) 2019 and 2021 from three bays in Lake Oahe, South Dakota. We stocked two bays with Walleye (30–32 mm; 255–1649 Walleye/ha), whereas one bay was unstocked and served as a reference. We estimated Smallmouth Bass population abundance using Schnabel capture–recapture models, and we used bioenergetics to estimate the percentage of stocked age‐0 Walleye consumed.ResultWe found age‐0 Walleye in up to 11.4% of Smallmouth Bass diets and 14.6% of adult Walleye diets during the poststocking period. A single Largemouth Bass consumed one Walleye at 3 days poststocking (DPS), whereas we did not identify Walleye in Northern Pike diets. Daily mean percent composition by weight (±95% confidence interval) of age‐0 Walleye in diets peaked at 43.2 ± 35.1% at 3 DPS for Smallmouth Bass and 49.8 ± 97.7% at 14 DPS for adult Walleye. Following the peaks, age‐0 Walleye percent composition by weight rapidly declined and was generally 0% after 25 DPS. Smallmouth Bass abundance was 0.4–5.6 fish/ha, whereas recaptures of other predator species were insufficient for reliable population estimates. We estimated that Smallmouth Bass consumed 29,930 age‐0 Walleye in 2019 and 12,535 age‐0 Walleye in 2021 (up to 14.7 ± 4.7% of stocked fish), potentially representing an important source of stocking mortality.ConclusionOur research provides insights into the effects of poststocking predation on age‐0 Walleye by Smallmouth Bass and, to a lesser extent, Walleye, Largemouth Bass, and Northern Pike. Managers should consider predation on stocked fingerling Walleye from resident predators and should contemplate alternative stocking locations or timing to reduce potential predation.
{"title":"Smallmouth Bass and Walleye predation on stocked age‐0 Walleye in Lake Oahe, South Dakota","authors":"Kyle Olivencia, Emily E. Grausgruber, Mark J. Fincel, Michael J. Weber","doi":"10.1002/nafm.10999","DOIUrl":"https://doi.org/10.1002/nafm.10999","url":null,"abstract":"ObjectiveWalleye <jats:italic>Sander vitreus</jats:italic> are important sport fish that are commonly stocked to supplement populations. Increases in Smallmouth Bass <jats:italic>Micropterus dolomieu</jats:italic> abundance have prompted concerns regarding potential predation by these and other piscivores on stocked Walleye. Our objectives were to assess the timing and duration of predation on stocked Walleye, the frequency of occurrence and percent composition of Walleye in predator diets, and the percentage of stocked Walleye consumed.MethodsWe collected Smallmouth Bass, adult Walleye, Largemouth Bass <jats:italic>M. nigricans</jats:italic>, and Northern Pike <jats:italic>Esox lucius</jats:italic> diets in May (prestocking) and June–September (poststocking) 2019 and 2021 from three bays in Lake Oahe, South Dakota. We stocked two bays with Walleye (30–32 mm; 255–1649 Walleye/ha), whereas one bay was unstocked and served as a reference. We estimated Smallmouth Bass population abundance using Schnabel capture–recapture models, and we used bioenergetics to estimate the percentage of stocked age‐0 Walleye consumed.ResultWe found age‐0 Walleye in up to 11.4% of Smallmouth Bass diets and 14.6% of adult Walleye diets during the poststocking period. A single Largemouth Bass consumed one Walleye at 3 days poststocking (DPS), whereas we did not identify Walleye in Northern Pike diets. Daily mean percent composition by weight (±95% confidence interval) of age‐0 Walleye in diets peaked at 43.2 ± 35.1% at 3 DPS for Smallmouth Bass and 49.8 ± 97.7% at 14 DPS for adult Walleye. Following the peaks, age‐0 Walleye percent composition by weight rapidly declined and was generally 0% after 25 DPS. Smallmouth Bass abundance was 0.4–5.6 fish/ha, whereas recaptures of other predator species were insufficient for reliable population estimates. We estimated that Smallmouth Bass consumed 29,930 age‐0 Walleye in 2019 and 12,535 age‐0 Walleye in 2021 (up to 14.7 ± 4.7% of stocked fish), potentially representing an important source of stocking mortality.ConclusionOur research provides insights into the effects of poststocking predation on age‐0 Walleye by Smallmouth Bass and, to a lesser extent, Walleye, Largemouth Bass, and Northern Pike. Managers should consider predation on stocked fingerling Walleye from resident predators and should contemplate alternative stocking locations or timing to reduce potential predation.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":"50 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140835166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bret C. Harvey, Jason L. White, Rodney J. Nakamoto, Steven F. Railsback
ObjectiveWe sought to measure a step‐pool restoration project's effects on a steelhead Oncorhynchus mykiss population and explore the capability of process‐based modeling to enhance understanding of the results.MethodsWe used before‐after–control‐impact monitoring in combination with a process‐based, individual‐based, spatially explicit fish population model to evaluate a stream restoration project that reconfigured the channel and primarily added step pools to a reach of a second‐order stream in northwestern California.ResultFive years of monitoring both before (2012–2016) and after (2018–2022) restoration indicated that restoration caused substantial increases in the abundance and biomass of steelhead. Individual growth rates and retention of fish in the study reach did not exhibit consistent patterns, even in the first 2 years after restoration, when fish abundance and biomass exhibited extreme increases of about fivefold. Model simulations predicted about a twofold increase in the abundance and biomass of steelhead in the restoration reach, which corresponded with the empirical results 4–5 years after restoration. The model also predicted a similar increase in the production of steelhead out‐migrants, a response we did not attempt to measure in the field.ConclusionStep‐pool restoration benefitted steelhead. The model's correspondence with empirical observations indicates its potential applicability to more complex resource management questions in the study area, such as how restoration will combine with changes in climate to affect the sustainability of salmonid populations.
{"title":"Empirical and model‐based evaluation of a step‐pool stream restoration project: Consequences for a highly valued fish population","authors":"Bret C. Harvey, Jason L. White, Rodney J. Nakamoto, Steven F. Railsback","doi":"10.1002/nafm.11000","DOIUrl":"https://doi.org/10.1002/nafm.11000","url":null,"abstract":"ObjectiveWe sought to measure a step‐pool restoration project's effects on a steelhead <jats:italic>Oncorhynchus mykiss</jats:italic> population and explore the capability of process‐based modeling to enhance understanding of the results.MethodsWe used before‐after–control‐impact monitoring in combination with a process‐based, individual‐based, spatially explicit fish population model to evaluate a stream restoration project that reconfigured the channel and primarily added step pools to a reach of a second‐order stream in northwestern California.ResultFive years of monitoring both before (2012–2016) and after (2018–2022) restoration indicated that restoration caused substantial increases in the abundance and biomass of steelhead. Individual growth rates and retention of fish in the study reach did not exhibit consistent patterns, even in the first 2 years after restoration, when fish abundance and biomass exhibited extreme increases of about fivefold. Model simulations predicted about a twofold increase in the abundance and biomass of steelhead in the restoration reach, which corresponded with the empirical results 4–5 years after restoration. The model also predicted a similar increase in the production of steelhead out‐migrants, a response we did not attempt to measure in the field.ConclusionStep‐pool restoration benefitted steelhead. The model's correspondence with empirical observations indicates its potential applicability to more complex resource management questions in the study area, such as how restoration will combine with changes in climate to affect the sustainability of salmonid populations.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":"36 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140835228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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