ObjectivePopulation demographics of invasive species are commonly evaluated to better develop management actions that are useful for reducing their abundance or controlling the population. Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix are emblematic invaders in the United States, where they continue to expand their range. There is currently no consensus about which hard structure from these species is best for age estimation. Our study objective was to compare the processing time and precision of five hard structures used for age estimation of both species.MethodsWe sampled fish in the lower Red River catchment of Oklahoma, Arkansas, and Texas during summer and autumn 2021–2022 and removed the lapillus otolith, left primary pectoral fin ray, postcleithrum, urohyal bone, and anterior‐most pterygiophore of the dorsal fin from both Bighead and Silver carp. The structures (n = 1204) were either embedded in epoxy or thin‐sectioned and mounted on slides. Two readers estimated the age of the fish by using each structure and came to a consensus. Processing time was recorded from the onset of laboratory processing to the termination of polishing the cross sections for age estimation.ResultProcessing of otoliths was comparable to or faster than processing of the other structures and resulted in the highest between‐reader agreement. The lowest coefficients of variation in age estimation were represented using lapillus otoliths for Bighead Carp and postcleithra for Silver Carp. Our age bias plots indicated that all other structures underestimated age relative to the lapillus otoliths.ConclusionOur results indicated that using lapillus otoliths for age estimation of these species would have the highest between‐reader agreement and would incur no additional laboratory processing time. However, validation is needed to assess whether lapillus otoliths correctly age these species. From a management perspective, use of this structure would facilitate improved population comparisons.
{"title":"Processing time and precision of aging structures for Bighead Carp and Silver Carp in the lower Red River catchment in the southern Great Plains","authors":"B. Birdsall, J. Dattilo, Z. Fuqua, S. K. Brewer","doi":"10.1002/nafm.11027","DOIUrl":"https://doi.org/10.1002/nafm.11027","url":null,"abstract":"ObjectivePopulation demographics of invasive species are commonly evaluated to better develop management actions that are useful for reducing their abundance or controlling the population. Bighead Carp <jats:italic>Hypophthalmichthys nobilis</jats:italic> and Silver Carp <jats:italic>H. molitrix</jats:italic> are emblematic invaders in the United States, where they continue to expand their range. There is currently no consensus about which hard structure from these species is best for age estimation. Our study objective was to compare the processing time and precision of five hard structures used for age estimation of both species.MethodsWe sampled fish in the lower Red River catchment of Oklahoma, Arkansas, and Texas during summer and autumn 2021–2022 and removed the lapillus otolith, left primary pectoral fin ray, postcleithrum, urohyal bone, and anterior‐most pterygiophore of the dorsal fin from both Bighead and Silver carp. The structures (<jats:italic>n</jats:italic> = 1204) were either embedded in epoxy or thin‐sectioned and mounted on slides. Two readers estimated the age of the fish by using each structure and came to a consensus. Processing time was recorded from the onset of laboratory processing to the termination of polishing the cross sections for age estimation.ResultProcessing of otoliths was comparable to or faster than processing of the other structures and resulted in the highest between‐reader agreement. The lowest coefficients of variation in age estimation were represented using lapillus otoliths for Bighead Carp and postcleithra for Silver Carp. Our age bias plots indicated that all other structures underestimated age relative to the lapillus otoliths.ConclusionOur results indicated that using lapillus otoliths for age estimation of these species would have the highest between‐reader agreement and would incur no additional laboratory processing time. However, validation is needed to assess whether lapillus otoliths correctly age these species. From a management perspective, use of this structure would facilitate improved population comparisons.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142176559","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}
Carissa M. Long, Yi‐Jiun Jean Tsai, Gonzalo C. Castillo, Tien‐Chieh Hung, Vanessa D. Tobias, Evan W. Carson
ObjectiveDelta Smelt Hypomesus transpacificus are thought to be close to extinction in the wild, which has spurred multiagency conservation efforts to supplement their population. In conjunction with these recent efforts, monitoring is needed to assess the effectiveness of supplementation. Such monitoring often uses large‐scale tagging of released fish to distinguish between hatchery‐origin and wild‐origin fish that are captured during later surveys.MethodsIn this study, we evaluated the use of visible implant elastomer tags in Delta Smelt to determine whether fish survival, fish growth, or tag retention were dependent on (1) tag color (blue, green, orange, red, yellow, and no‐tag control) or (2) tagged body location (posterior‐dorsal, anterior‐dorsal, mid‐lateral line, and no‐tag control).ResultOver 165 days of the first experiment, there was no difference in growth rate (mean = 0.073 mm/d, range = 0.072–0.075 mm/d) or survival (mean = 68%, range = 63–77%) among tag colors. Across all color groups, mean tag retention was 96% (range = 87–100%). Over 120 days of the second experiment, tag location had no influence on fish growth rate (mean = 0.064 mm/d, range = 0.062–0.067 mm/d) or survival (mean = 50%, range = 43–58%). For the surviving fish in experiment 2, the tags that were placed at the mid‐lateral line were retained less (84% on day 120) than those at posterior‐dorsal and anterior‐dorsal locations (99% and 98%, respectively).ConclusionOur results suggest that visible implant elastomer tagging is a suitable method for marking adult Delta Smelt (>50 mm fork length) for up to 165 days and can be useful for conservation monitoring efforts.
{"title":"Evaluation of visible implant elastomer (VIE) tags for use in supplementation of an endangered estuarine fish","authors":"Carissa M. Long, Yi‐Jiun Jean Tsai, Gonzalo C. Castillo, Tien‐Chieh Hung, Vanessa D. Tobias, Evan W. Carson","doi":"10.1002/nafm.11024","DOIUrl":"https://doi.org/10.1002/nafm.11024","url":null,"abstract":"ObjectiveDelta Smelt <jats:italic>Hypomesus transpacificus</jats:italic> are thought to be close to extinction in the wild, which has spurred multiagency conservation efforts to supplement their population. In conjunction with these recent efforts, monitoring is needed to assess the effectiveness of supplementation. Such monitoring often uses large‐scale tagging of released fish to distinguish between hatchery‐origin and wild‐origin fish that are captured during later surveys.MethodsIn this study, we evaluated the use of visible implant elastomer tags in Delta Smelt to determine whether fish survival, fish growth, or tag retention were dependent on (1) tag color (blue, green, orange, red, yellow, and no‐tag control) or (2) tagged body location (posterior‐dorsal, anterior‐dorsal, mid‐lateral line, and no‐tag control).ResultOver 165 days of the first experiment, there was no difference in growth rate (mean = 0.073 mm/d, range = 0.072–0.075 mm/d) or survival (mean = 68%, range = 63–77%) among tag colors. Across all color groups, mean tag retention was 96% (range = 87–100%). Over 120 days of the second experiment, tag location had no influence on fish growth rate (mean = 0.064 mm/d, range = 0.062–0.067 mm/d) or survival (mean = 50%, range = 43–58%). For the surviving fish in experiment 2, the tags that were placed at the mid‐lateral line were retained less (84% on day 120) than those at posterior‐dorsal and anterior‐dorsal locations (99% and 98%, respectively).ConclusionOur results suggest that visible implant elastomer tagging is a suitable method for marking adult Delta Smelt (>50 mm fork length) for up to 165 days and can be useful for conservation monitoring efforts.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142176561","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}
Michelle A. Briggs, Hayley C. Glassic, Christopher S. Guy, Scott T. Opitz, Jay J. Rotella, David A. Schmetterling
ObjectiveLong‐term standardized monitoring programs are fundamental to assessing how fish populations respond to anthropogenic stressors. Standardized monitoring programs may need to adopt new methods to adapt to rapid environmental changes that are associated with a changing climate. In the upper Yellowstone River, Montana, biologists have used a standardized, mark–recapture monitoring protocol to annually estimate the abundance of trout since 1978 to assess population status and trends. However, within the past two decades, climate change has caused changes in discharge timing that have prevented standardized monitoring from occurring annually.MethodsWe investigated the feasibility of using two analytical methods, N‐mixture models and mean capture probability, for estimating the abundance of three trout species in the upper Yellowstone River using the historical long‐term data set; these methods allow abundance to be estimated when a mark–recapture estimate cannot be obtained due to hydrologic conditions.ResultWhen compared with abundance estimates from mark–recapture methods, N‐mixture models most often resulted in negatively biased abundance estimates, whereas mean capture probability analyses resulted in positively biased abundance estimates. Additionally, N‐mixture models produced negatively biased estimates when tested against true abundance values from simulated data sets. The bias in the N‐mixture model estimates was caused by poor model fit and variation in capture probability. The bias in the mean capture probability estimates was caused by heterogeneity in capture probability, likely caused by variable environmental conditions, which were not accounted for in the models.ConclusionN‐mixture models and mean capture probability are not viable alternatives for estimating abundance in the upper Yellowstone River. Thus, exploring additional adaptations to sampling methodologies and analytical approaches, including models that require individually marked fish, will be valuable for this system. Climate change will undoubtedly necessitate changes to standardized sampling methods throughout the world; thus, developing alternative sampling and analytical methods will be important for maintaining the utility of long‐term data sets.
{"title":"Adapting standardized trout monitoring to a changing climate for the upper Yellowstone River, Montana, USA","authors":"Michelle A. Briggs, Hayley C. Glassic, Christopher S. Guy, Scott T. Opitz, Jay J. Rotella, David A. Schmetterling","doi":"10.1002/nafm.11026","DOIUrl":"https://doi.org/10.1002/nafm.11026","url":null,"abstract":"ObjectiveLong‐term standardized monitoring programs are fundamental to assessing how fish populations respond to anthropogenic stressors. Standardized monitoring programs may need to adopt new methods to adapt to rapid environmental changes that are associated with a changing climate. In the upper Yellowstone River, Montana, biologists have used a standardized, mark–recapture monitoring protocol to annually estimate the abundance of trout since 1978 to assess population status and trends. However, within the past two decades, climate change has caused changes in discharge timing that have prevented standardized monitoring from occurring annually.MethodsWe investigated the feasibility of using two analytical methods, N‐mixture models and mean capture probability, for estimating the abundance of three trout species in the upper Yellowstone River using the historical long‐term data set; these methods allow abundance to be estimated when a mark–recapture estimate cannot be obtained due to hydrologic conditions.ResultWhen compared with abundance estimates from mark–recapture methods, N‐mixture models most often resulted in negatively biased abundance estimates, whereas mean capture probability analyses resulted in positively biased abundance estimates. Additionally, N‐mixture models produced negatively biased estimates when tested against true abundance values from simulated data sets. The bias in the N‐mixture model estimates was caused by poor model fit and variation in capture probability. The bias in the mean capture probability estimates was caused by heterogeneity in capture probability, likely caused by variable environmental conditions, which were not accounted for in the models.ConclusionN‐mixture models and mean capture probability are not viable alternatives for estimating abundance in the upper Yellowstone River. Thus, exploring additional adaptations to sampling methodologies and analytical approaches, including models that require individually marked fish, will be valuable for this system. Climate change will undoubtedly necessitate changes to standardized sampling methods throughout the world; thus, developing alternative sampling and analytical methods will be important for maintaining the utility of long‐term data sets.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142176560","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}
ObjectiveIn a changing climate, the effects of air temperature, precipitation, and groundwater on water temperature and thermal habitat suitability for Gulf Sturgeon Acipenser desotoi, listed as threatened under the U.S. Endangered Species Act, are not well understood. Hence, we incorporated these factors into thermal habitat models to forecast how Gulf Sturgeon may be affected by wide‐ranging climate change scenarios in 2024–2074.MethodsUsing data from the Choctawhatchee River, Florida, we developed precipitation‐ and groundwater‐corrected air–water temperature models, compared their accuracy with that of conventional air–water temperature models used in fisheries management, and projected future Gulf Sturgeon thermal habitat suitability for normal physiological functioning and fieldwork (i.e., population sampling and telemetry surgeries) in summer (May–August) under 16 climate change scenarios.ResultPrecipitation‐ and groundwater‐corrected models were more accurate than conventional air–water temperature models (mean improvement in adjusted R2 = +0.45; range = +0.09 to +0.75). Water temperature was projected to warm at widely variable rates across climate change scenarios encompassing different air temperature, precipitation, and groundwater regimes. Importantly, Gulf Sturgeon summer aggregation areas were cooler and influenced more by precipitation and groundwater and less by air temperature than were non‐aggregation areas. If precipitation and groundwater—as drivers of cooling—become warm in a changing climate, summer aggregation areas were projected to exhibit thermal habitat degradation equivalent to or greater than that of non‐aggregation areas.ConclusionOur results add hydrological context to the premise that aggregation areas provide cool water and energetic savings for Gulf Sturgeon during summer, underscoring the importance of protecting these habitats through groundwater conservation, water quality monitoring, and riparian/watershed habitat management. Our findings indicate that identifying thermally appropriate times for fieldwork activities will be increasingly important and time‐restricted as climate change intensifies. However, our research provides managers with a portfolio of water temperature models and an accurate, cost‐effective, management‐relevant approach to forecasting thermal habitat conditions for Gulf Sturgeon and other species in a changing climate.
{"title":"Cold blood in warming waters: Effects of air temperature, precipitation, and groundwater on Gulf Sturgeon thermal habitats in a changing climate","authors":"Andrew K. Carlson, Bethany M. Gaffey","doi":"10.1002/nafm.11028","DOIUrl":"https://doi.org/10.1002/nafm.11028","url":null,"abstract":"ObjectiveIn a changing climate, the effects of air temperature, precipitation, and groundwater on water temperature and thermal habitat suitability for Gulf Sturgeon <jats:italic>Acipenser desotoi</jats:italic>, listed as threatened under the U.S. Endangered Species Act, are not well understood. Hence, we incorporated these factors into thermal habitat models to forecast how Gulf Sturgeon may be affected by wide‐ranging climate change scenarios in 2024–2074.MethodsUsing data from the Choctawhatchee River, Florida, we developed precipitation‐ and groundwater‐corrected air–water temperature models, compared their accuracy with that of conventional air–water temperature models used in fisheries management, and projected future Gulf Sturgeon thermal habitat suitability for normal physiological functioning and fieldwork (i.e., population sampling and telemetry surgeries) in summer (May–August) under 16 climate change scenarios.ResultPrecipitation‐ and groundwater‐corrected models were more accurate than conventional air–water temperature models (mean improvement in adjusted <jats:italic>R</jats:italic><jats:sup>2</jats:sup> = +0.45; range = +0.09 to +0.75). Water temperature was projected to warm at widely variable rates across climate change scenarios encompassing different air temperature, precipitation, and groundwater regimes. Importantly, Gulf Sturgeon summer aggregation areas were cooler and influenced more by precipitation and groundwater and less by air temperature than were non‐aggregation areas. If precipitation and groundwater—as drivers of cooling—become warm in a changing climate, summer aggregation areas were projected to exhibit thermal habitat degradation equivalent to or greater than that of non‐aggregation areas.ConclusionOur results add hydrological context to the premise that aggregation areas provide cool water and energetic savings for Gulf Sturgeon during summer, underscoring the importance of protecting these habitats through groundwater conservation, water quality monitoring, and riparian/watershed habitat management. Our findings indicate that identifying thermally appropriate times for fieldwork activities will be increasingly important and time‐restricted as climate change intensifies. However, our research provides managers with a portfolio of water temperature models and an accurate, cost‐effective, management‐relevant approach to forecasting thermal habitat conditions for Gulf Sturgeon and other species in a changing climate.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142176592","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}
Dale E. Logsdon, Steven M. Shroyer, Askhan Shametov, Loren M. Miller
ObjectiveA genetically distinct strain of Walleye Sander vitreus (southern Minnesota strain [SMS]) persists in southern Minnesota lakes despite decades of stocking more easily obtained strains from outside of the region. Because of the regional performance advantage inferred by this persistence, we conducted in situ experiments to compare survival and stocking cost of SMS Walleye fry against those of a frequently stocked northern Minnesota strain (Mississippi headwaters strain [MIS]) to determine whether it is beneficial to expand SMS fry stocking in lieu of historic practices.MethodsWe conducted four paired stockings of oxytetracycline‐marked SMS fry and MIS fry into six southern Minnesota lakes and then sampled the fish as fall fingerlings during 2018, 2019, 2021, and 2022. We then used fluorescent microscopy and parentage‐based tagging techniques to discern the stocked strains for comparison of growth and survival. We also obtained production and stocking cost data from agency records to calculate relative stocking costs.ResultBy the end of their first summer, SMS Walleye from all but two stockings exhibited higher survival than MIS Walleye. Despite higher initial costs to produce SMS fry, their higher survival to fall fingerlings made the stocking of SMS fry more cost effective than MIS fry stocking. Natural reproduction was also identified in several stocked lakes, most of which consisted of either high or increasing levels of SMS ancestry.ConclusionA local strain can outperform nonlocal strains at a level that can overcome additional costs of developing a new egg source. In addition, natural reproduction of local‐strain Walleye may reduce or eliminate the need for future stocking.
目的 尽管几十年来一直在明尼苏达州南部的湖泊中放养更容易从该地区以外获得的品系，但明尼苏达州南部湖泊中仍然存在一个基因独特的瓦勒耶鱼品系（Sander vitreus）（明尼苏达州南部品系[SMS]）。由于这种持续性推断出的区域性能优势，我们进行了原位实验，将 SMS 瓦勒耶鱼苗的存活率和放养成本与经常放养的明尼苏达州北部品系（密西西比河源头品系 [MIS]）的存活率和放养成本进行比较，以确定扩大 SMS 鱼苗放养以取代历史做法是否有益。方法我们在明尼苏达州南部的六个湖泊中进行了四次土霉素标记的SMS鱼苗和MIS鱼苗的配对放流，然后在2018年、2019年、2021年和2022年的秋季幼鱼期进行采样。然后，我们使用荧光显微镜和基于亲本的标签技术来分辨放养的品系，以比较其生长和存活情况。我们还从机构记录中获取了生产和放养成本数据，以计算相对放养成本。结果到第一个夏季结束时，除两次放养外，其他所有放养的 SMS 瓦利耶鱼的存活率均高于 MIS 瓦利耶鱼。尽管生产 SMS 鱼苗的初始成本较高，但它们到秋季鱼苗的存活率较高，因此放养 SMS 鱼苗比放养 MIS 鱼苗更具成本效益。在几个放养的湖泊中也发现了自然繁殖现象，其中大部分湖泊都有较高或越来越高的 SMS 血统。此外，本地品系马口鱼的自然繁殖可减少或消除未来放养的需要。
{"title":"Performance and cost advantage of stocking locally sourced Walleye fry into southern Minnesota lakes","authors":"Dale E. Logsdon, Steven M. Shroyer, Askhan Shametov, Loren M. Miller","doi":"10.1002/nafm.11025","DOIUrl":"https://doi.org/10.1002/nafm.11025","url":null,"abstract":"ObjectiveA genetically distinct strain of Walleye <jats:italic>Sander vitreus</jats:italic> (southern Minnesota strain [SMS]) persists in southern Minnesota lakes despite decades of stocking more easily obtained strains from outside of the region. Because of the regional performance advantage inferred by this persistence, we conducted in situ experiments to compare survival and stocking cost of SMS Walleye fry against those of a frequently stocked northern Minnesota strain (Mississippi headwaters strain [MIS]) to determine whether it is beneficial to expand SMS fry stocking in lieu of historic practices.MethodsWe conducted four paired stockings of oxytetracycline‐marked SMS fry and MIS fry into six southern Minnesota lakes and then sampled the fish as fall fingerlings during 2018, 2019, 2021, and 2022. We then used fluorescent microscopy and parentage‐based tagging techniques to discern the stocked strains for comparison of growth and survival. We also obtained production and stocking cost data from agency records to calculate relative stocking costs.ResultBy the end of their first summer, SMS Walleye from all but two stockings exhibited higher survival than MIS Walleye. Despite higher initial costs to produce SMS fry, their higher survival to fall fingerlings made the stocking of SMS fry more cost effective than MIS fry stocking. Natural reproduction was also identified in several stocked lakes, most of which consisted of either high or increasing levels of SMS ancestry.ConclusionA local strain can outperform nonlocal strains at a level that can overcome additional costs of developing a new egg source. In addition, natural reproduction of local‐strain Walleye may reduce or eliminate the need for future stocking.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142176601","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}
Dray D. Carl, Daniel E. Shoup, Ryan Ryswyk, Cliff Sager, Richard Snow
ObjectiveSaugeye (Sauger Sander canadensis × Walleye S. vitreus) have been introduced in reservoirs for several purposes, including as a top‐down control to combat stunting in crappie Pomoxis spp. populations. However, no comprehensive diet evaluation has been completed in southern reservoirs. Our objectives were to assess variability in saugeye diet compositions, explore factors influencing crappie presence in saugeye diets, and investigate trends in prey size to inform management strategies regarding predatory control of crappie populations.MethodsWe collected 2638 saugeye diets from six Oklahoma reservoirs. We used permutational multivariate analysis of variance to test differences in diet compositions among saugeye lengths, study reservoirs, and seasons, and we used logistic regression models to correlate the presence of crappie in diets with saugeye size, season, crappie abundance, productivity, and turbidity. Finally, we used bivariate plots of diet indices and quantile regression to explore trends in prey importance and prey size relative to saugeye size.ResultSaugeye diet compositions were best explained by saugeye size, followed by study reservoir and season. Saugeye exhibited an ontogenetic shift from Inland Silverside Menidia beryllina to shad Dorosoma spp., and crappie were eaten infrequently in comparison. The presence of crappie prey in diets was most correlated with saugeye size (primarily large saugeye), followed by higher crappie abundance, lower reservoir productivity, and season (highest in fall). Saugeye consumed larger prey than most piscivores relative to predator size.ConclusionOur results indicated that dominant prey of saugeye transitioned from smaller‐bodied fishes to larger shad as they grew when both prey types were available, which may have implications for growth and recruitment. Ultimately, the low and variable use of crappie prey may lead to inconsistent predatory effects on crappie populations, and large saugeye may exert greater top‐down pressure on crappie in lakes with lower productivity or higher crappie abundance.
{"title":"Saugeye diets in southern reservoirs and insight for predatory control of stunted crappie","authors":"Dray D. Carl, Daniel E. Shoup, Ryan Ryswyk, Cliff Sager, Richard Snow","doi":"10.1002/nafm.11022","DOIUrl":"https://doi.org/10.1002/nafm.11022","url":null,"abstract":"ObjectiveSaugeye (Sauger <jats:italic>Sander canadensis</jats:italic> × Walleye <jats:italic>S. vitreus</jats:italic>) have been introduced in reservoirs for several purposes, including as a top‐down control to combat stunting in crappie <jats:italic>Pomoxis</jats:italic> spp. populations. However, no comprehensive diet evaluation has been completed in southern reservoirs. Our objectives were to assess variability in saugeye diet compositions, explore factors influencing crappie presence in saugeye diets, and investigate trends in prey size to inform management strategies regarding predatory control of crappie populations.MethodsWe collected 2638 saugeye diets from six Oklahoma reservoirs. We used permutational multivariate analysis of variance to test differences in diet compositions among saugeye lengths, study reservoirs, and seasons, and we used logistic regression models to correlate the presence of crappie in diets with saugeye size, season, crappie abundance, productivity, and turbidity. Finally, we used bivariate plots of diet indices and quantile regression to explore trends in prey importance and prey size relative to saugeye size.ResultSaugeye diet compositions were best explained by saugeye size, followed by study reservoir and season. Saugeye exhibited an ontogenetic shift from Inland Silverside <jats:italic>Menidia beryllina</jats:italic> to shad <jats:italic>Dorosoma</jats:italic> spp., and crappie were eaten infrequently in comparison. The presence of crappie prey in diets was most correlated with saugeye size (primarily large saugeye), followed by higher crappie abundance, lower reservoir productivity, and season (highest in fall). Saugeye consumed larger prey than most piscivores relative to predator size.ConclusionOur results indicated that dominant prey of saugeye transitioned from smaller‐bodied fishes to larger shad as they grew when both prey types were available, which may have implications for growth and recruitment. Ultimately, the low and variable use of crappie prey may lead to inconsistent predatory effects on crappie populations, and large saugeye may exert greater top‐down pressure on crappie in lakes with lower productivity or higher crappie abundance.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141930568","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}
Johan O. Munkeby, Jan G. Davidsen, Torgeir B. Havn, Eva M. Ulvan, Tor F. Næsje, Dag H. Karlsen, Øyvind Solem, Robert J. Lennox
ObjectiveSurveillance fishing surveys can be performed to estimate the proportion of farmed salmon represented in the spawning stock of native Atlantic Salmon Salmo salar populations. These surveys take place after the recreational fishing period and therefore closer to the spawning period than the open recreational fishing season. Although catch‐and‐release angling has been demonstrated to affect salmon migration during the summer months, surveillance fishing that is conducted close to the spawning time could have more severe effects.MethodsTo test this, the migration distance of Atlantic Salmon (n = 74) caught in the Orkla River, Norway, was tracked by use of radiotelemetry. One group was tagged during the regular fishing season in the summer (control group), whereas another group was tagged in autumn during surveillance fishing (surveillance group).ResultSixty‐one salmon remained for analysis after we excluded fish that were recaptured, died, or migrated to other rivers. Relocation of the salmon during autumn (October 11–31) was used to compare movements and test for differences in migration using negative binomial regression because distances were nonnegative integers. During the tracking period, the surveillance group moved 12 ± 14 km (mean ± standard deviation) and the control group moved 13 ± 15 km; both groups moved 1 ± 2 km/day on average. There was no evidence that surveillance fishing impacted movement of the salmon compared to controls. However, one salmon died after tagging and three were not released due to injuries; total mortality of 9% during surveillance fishing could be unsustainable for smaller populations. Consequently, factors such as surveillance sample size, the status of the salmon population, and the population size should be assessed for each river individually when deciding the necessity of and approach to surveillance fishing.ConclusionThe results support existing recommendations to use careful handling and to end surveillance at least 2 weeks prior to the expected onset of spawning, thus providing a sufficiently long period for recovery after surveillance fishing.
{"title":"The effect of surveillance fishing on migration distance of Atlantic Salmon during the spawning period","authors":"Johan O. Munkeby, Jan G. Davidsen, Torgeir B. Havn, Eva M. Ulvan, Tor F. Næsje, Dag H. Karlsen, Øyvind Solem, Robert J. Lennox","doi":"10.1002/nafm.11020","DOIUrl":"https://doi.org/10.1002/nafm.11020","url":null,"abstract":"ObjectiveSurveillance fishing surveys can be performed to estimate the proportion of farmed salmon represented in the spawning stock of native Atlantic Salmon <jats:italic>Salmo salar</jats:italic> populations. These surveys take place after the recreational fishing period and therefore closer to the spawning period than the open recreational fishing season. Although catch‐and‐release angling has been demonstrated to affect salmon migration during the summer months, surveillance fishing that is conducted close to the spawning time could have more severe effects.MethodsTo test this, the migration distance of Atlantic Salmon (<jats:italic>n</jats:italic> = 74) caught in the Orkla River, Norway, was tracked by use of radiotelemetry. One group was tagged during the regular fishing season in the summer (control group), whereas another group was tagged in autumn during surveillance fishing (surveillance group).ResultSixty‐one salmon remained for analysis after we excluded fish that were recaptured, died, or migrated to other rivers. Relocation of the salmon during autumn (October 11–31) was used to compare movements and test for differences in migration using negative binomial regression because distances were nonnegative integers. During the tracking period, the surveillance group moved 12 ± 14 km (mean ± standard deviation) and the control group moved 13 ± 15 km; both groups moved 1 ± 2 km/day on average. There was no evidence that surveillance fishing impacted movement of the salmon compared to controls. However, one salmon died after tagging and three were not released due to injuries; total mortality of 9% during surveillance fishing could be unsustainable for smaller populations. Consequently, factors such as surveillance sample size, the status of the salmon population, and the population size should be assessed for each river individually when deciding the necessity of and approach to surveillance fishing.ConclusionThe results support existing recommendations to use careful handling and to end surveillance at least 2 weeks prior to the expected onset of spawning, thus providing a sufficiently long period for recovery after surveillance fishing.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141930503","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}
ObjectiveColdwater releases from reservoirs support economically valuable sport fisheries for salmonids in the southern United States. The tailwater of Lewis Smith Dam in northwestern Alabama supports the only coldwater fishery in the state, with monthly stockings of about 1500 catchable‐size (200–406 mm total length) Rainbow Trout Oncorhynchus mykiss. Historically, the return to angler creel has been low in this fishery, and few large Rainbow Trout are caught. Numerous potential predators of stocked trout exist in this tailwater, including Gulf‐strain Striped Bass Morone saxatilis, which are stocked annually in a downstream reservoir. Thus, the objective of this study was to quantify the amount of predation, which occurs on Rainbow Trout in the Smith Lake tailwater.MethodsPotential predators of Rainbow Trout were collected six times over a 3‐week period after stocking in March, May, June, and October 2018.ResultRainbow Trout were found in the stomachs of Striped Bass, hybrid striped bass (White Bass Morone chrysops × Striped Bass), Largemouth Bass Micropterus nigricans, and Chain Pickerel Esox niger. Only Striped Bass exhibited substantial predation on stocked Rainbow Trout, with 75% of these fish having at least one trout in their stomach. Of all identifiable prey items, Rainbow Trout composed 82% of the Striped Bass diet by number across all four sample months and constituted more than 65% of the Striped Bass diet by number in each sample month. Bioenergetics models predicted that a population of 500 Striped Bass living continuously in the tailwater from March through October could consume all Rainbow Trout stocked during each month. If Striped Bass vacated the area or switched from trout to other diet items for one‐third of each month, they could still consume almost 60% of stocked trout.ConclusionResults of this study demonstrate that Striped Bass are significant predators of Rainbow Trout in the Smith Lake tailwater and are likely one of the main factors mediating Rainbow Trout survival and persistence in this fishery.
{"title":"Predation of stocked Rainbow Trout in an Alabama tailwater","authors":"Sarah M. Baker, Steven M. Sammons","doi":"10.1002/nafm.11017","DOIUrl":"https://doi.org/10.1002/nafm.11017","url":null,"abstract":"ObjectiveColdwater releases from reservoirs support economically valuable sport fisheries for salmonids in the southern United States. The tailwater of Lewis Smith Dam in northwestern Alabama supports the only coldwater fishery in the state, with monthly stockings of about 1500 catchable‐size (200–406 mm total length) Rainbow Trout <jats:italic>Oncorhynchus mykiss</jats:italic>. Historically, the return to angler creel has been low in this fishery, and few large Rainbow Trout are caught. Numerous potential predators of stocked trout exist in this tailwater, including Gulf‐strain Striped Bass <jats:italic>Morone saxatilis</jats:italic>, which are stocked annually in a downstream reservoir. Thus, the objective of this study was to quantify the amount of predation, which occurs on Rainbow Trout in the Smith Lake tailwater.MethodsPotential predators of Rainbow Trout were collected six times over a 3‐week period after stocking in March, May, June, and October 2018.ResultRainbow Trout were found in the stomachs of Striped Bass, hybrid striped bass (White Bass <jats:italic>Morone chrysops</jats:italic> × Striped Bass), Largemouth Bass <jats:italic>Micropterus nigricans</jats:italic>, and Chain Pickerel <jats:italic>Esox niger</jats:italic>. Only Striped Bass exhibited substantial predation on stocked Rainbow Trout, with 75% of these fish having at least one trout in their stomach. Of all identifiable prey items, Rainbow Trout composed 82% of the Striped Bass diet by number across all four sample months and constituted more than 65% of the Striped Bass diet by number in each sample month. Bioenergetics models predicted that a population of 500 Striped Bass living continuously in the tailwater from March through October could consume all Rainbow Trout stocked during each month. If Striped Bass vacated the area or switched from trout to other diet items for one‐third of each month, they could still consume almost 60% of stocked trout.ConclusionResults of this study demonstrate that Striped Bass are significant predators of Rainbow Trout in the Smith Lake tailwater and are likely one of the main factors mediating Rainbow Trout survival and persistence in this fishery.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141613695","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}
Courtnie L. Ghere, Ryan S. Hardy, Sean M. Wilson, Michael C. Quist
ObjectiveSuccessful 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.MethodsAge 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).ResultBetween‐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.ConclusionAgeing 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.
{"title":"Evaluation of techniques for estimating the age and growth of known‐age White Sturgeon","authors":"Courtnie L. Ghere, Ryan S. Hardy, Sean M. Wilson, Michael C. Quist","doi":"10.1002/nafm.11021","DOIUrl":"https://doi.org/10.1002/nafm.11021","url":null,"abstract":"ObjectiveSuccessful 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 <jats:italic>Acipenser transmontanus</jats:italic>. The mark–recapture history information for White Sturgeon allowed for the evaluation of fin rays for age and growth analysis.MethodsAge was estimated from pectoral fin rays of known‐age White Sturgeon (<jats:italic>n</jats:italic> = 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).ResultBetween‐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.ConclusionAgeing 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.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141613909","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}
Hilary B. Treanor, Todd M. Koel, Andriana R. Puchany, Colleen R. Detjens, Molly A. H. Webb
ObjectiveUnderstanding recruitment dynamics is necessary to predict population‐level responses to exploitation, management actions, or anthropogenic influences. Fecundity is commonly used as a metric of recruitment dynamics and can guide successful management of fisheries. However, an individual female's fecundity is not constant over time; females resorb ovarian follicles to regulate fecundity as they approach spawning. This suggests that sampling for fecundity too early may produce inaccurate estimates of relative fecundity. In Yellowstone National Park, suppression of invasive Lake Trout Salvelinus namaycush reduced the abundance of mature fish by 92% between 2012 and 2022. The continued efficacy of this suppression effort requires accurate assessments of reproductive potential of the population that remains.MethodsWe sought to determine whether the timing of ovarian follicle collection affected estimates of mean relative fecundity. We collected ovarian follicles from female Lake Trout, which are autumn spawners, between mid‐August and early October in 2021 and 2022. The number of ovarian follicles per sample was counted to obtain estimates of relative fecundity for each female.ResultWe observed a 13% decline in estimated mean relative fecundity between individuals that were sampled before mid‐September and those that were sampled after mid‐September.ConclusionOur data support strategic timing of fecundity sampling to best capture the true reproductive capability of a population, which is a key metric used in models that guide adaptive management of fishes.
{"title":"Don't count your eggs before they resorb: Early collection of ovarian follicles influences estimates of Lake Trout fecundity in Yellowstone Lake","authors":"Hilary B. Treanor, Todd M. Koel, Andriana R. Puchany, Colleen R. Detjens, Molly A. H. Webb","doi":"10.1002/nafm.11015","DOIUrl":"https://doi.org/10.1002/nafm.11015","url":null,"abstract":"ObjectiveUnderstanding recruitment dynamics is necessary to predict population‐level responses to exploitation, management actions, or anthropogenic influences. Fecundity is commonly used as a metric of recruitment dynamics and can guide successful management of fisheries. However, an individual female's fecundity is not constant over time; females resorb ovarian follicles to regulate fecundity as they approach spawning. This suggests that sampling for fecundity too early may produce inaccurate estimates of relative fecundity. In Yellowstone National Park, suppression of invasive Lake Trout <jats:italic>Salvelinus namaycush</jats:italic> reduced the abundance of mature fish by 92% between 2012 and 2022. The continued efficacy of this suppression effort requires accurate assessments of reproductive potential of the population that remains.MethodsWe sought to determine whether the timing of ovarian follicle collection affected estimates of mean relative fecundity. We collected ovarian follicles from female Lake Trout, which are autumn spawners, between mid‐August and early October in 2021 and 2022. The number of ovarian follicles per sample was counted to obtain estimates of relative fecundity for each female.ResultWe observed a 13% decline in estimated mean relative fecundity between individuals that were sampled before mid‐September and those that were sampled after mid‐September.ConclusionOur data support strategic timing of fecundity sampling to best capture the true reproductive capability of a population, which is a key metric used in models that guide adaptive management of fishes.","PeriodicalId":19263,"journal":{"name":"North American Journal of Fisheries Management","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141613699","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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