Dylan S. Cunningham, Douglas C. Braun, Jonathan W. Moore, Amanda M. Martens
Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print.
加拿大渔业和水产科学杂志》，提前印刷。
{"title":"Forestry and stream temperatures: a response to comment by R.D. Moore","authors":"Dylan S. Cunningham, Douglas C. Braun, Jonathan W. Moore, Amanda M. Martens","doi":"10.1139/cjfas-2023-0306","DOIUrl":"https://doi.org/10.1139/cjfas-2023-0306","url":null,"abstract":"Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. <br/>","PeriodicalId":9515,"journal":{"name":"Canadian Journal of Fisheries and Aquatic Sciences","volume":"121 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139951202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print.
加拿大渔业和水产科学杂志》，提前印刷。
{"title":"Correction: Accounting for transient dynamics could improve the use of marine protected areas as a reference point for fisheries management","authors":"V.I. Quennessen, E.A. Babcock, J.W. White","doi":"10.1139/cjfas-2024-0024","DOIUrl":"https://doi.org/10.1139/cjfas-2024-0024","url":null,"abstract":"Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. <br/>","PeriodicalId":9515,"journal":{"name":"Canadian Journal of Fisheries and Aquatic Sciences","volume":"26 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139773085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. Migratory freshwater fish species are particularly susceptible to population decline because they rely on multiple habitats and open passages to complete their life cycle. Understanding the migratory patterns of cyprinids is thus essential for their management and conservation. Gnathopogon caerelescens, a small cyprinid species endemic to Lake Biwa (Japan), is one of the most important targets of inland fisheries. However, their abundance has dramatically decreased. By using an extensive alizarin complexone-mark-and-recapture program for of G. caerelescens juveniles, together with the collaboration of commercial fishermen, this cyprinid fish was demonstrated as: (1) migrating from a nursery lagoon toward the main lake and moving along the near-shore from spring to autumn; (2) migrating from the near-shore shallow habitats to off-shore deep habitats from autumn to winter; and (3) migrating to a nursery lagoon from off-shore deep habitats from winter to spring. These results highlighted the importance of protecting individual spawning/nursery habitats, and maintaining connectivity between each spawning/nursery habitat and the lake system.
加拿大渔业和水产科学杂志》（Canadian Journal of Fisheries and Aquatic Sciences），提前印刷。 洄游淡水鱼类尤其容易出现种群数量下降的情况，因为它们依赖多种栖息地和开放通道来完成生命周期。因此，了解鲤科鱼类的洄游模式对其管理和保护至关重要。Gnathopogon caerelescens是琵琶湖（日本）特有的小型鲤科鱼类，是内陆渔业最重要的捕捞对象之一。然而，它们的数量却急剧下降。通过对 G. caerelescens 幼鱼进行广泛的茜素络合-标记-再捕捉计划，并与商业渔民合作，证明了这种鲤科鱼类的以下特征：(1) 从春季到秋季，从育苗环礁湖向主湖区洄游，并沿近岸移动；(2) 从秋季到冬季，从近岸浅层生境向近岸深层生境洄游；(3) 从冬季到春季，从近岸深层生境向育苗环礁湖洄游。这些结果凸显了保护单个产卵/育苗栖息地以及保持每个产卵/育苗栖息地与湖泊系统之间的连通性的重要性。
{"title":"Apparent migration and natal homing of a small minnow in a large ancient lake","authors":"Takeshi Kikko, Takuya Sato, Minoru Kanaiwa, Daisuke Ishizaki, Kunihiko Kuwamura, Haruo Okamoto, Atsuhiko Ide, Morihito Nemoto, Shoichiro Takeoka, Yoshiaki Kai, Kouji Nakayama, Yasuhiro Fujioka","doi":"10.1139/cjfas-2022-0207","DOIUrl":"https://doi.org/10.1139/cjfas-2022-0207","url":null,"abstract":"Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. <br/> Migratory freshwater fish species are particularly susceptible to population decline because they rely on multiple habitats and open passages to complete their life cycle. Understanding the migratory patterns of cyprinids is thus essential for their management and conservation. Gnathopogon caerelescens, a small cyprinid species endemic to Lake Biwa (Japan), is one of the most important targets of inland fisheries. However, their abundance has dramatically decreased. By using an extensive alizarin complexone-mark-and-recapture program for of G. caerelescens juveniles, together with the collaboration of commercial fishermen, this cyprinid fish was demonstrated as: (1) migrating from a nursery lagoon toward the main lake and moving along the near-shore from spring to autumn; (2) migrating from the near-shore shallow habitats to off-shore deep habitats from autumn to winter; and (3) migrating to a nursery lagoon from off-shore deep habitats from winter to spring. These results highlighted the importance of protecting individual spawning/nursery habitats, and maintaining connectivity between each spawning/nursery habitat and the lake system.","PeriodicalId":9515,"journal":{"name":"Canadian Journal of Fisheries and Aquatic Sciences","volume":"19 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139755026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Leire Citores, Leire Ibaibarriaga, Maria Santos, Andres Uriarte
Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. Biomass estimates of fish resources by the daily egg production method (DEPM) are sensitive to the high variability of the daily egg production (P0) and egg mortality (Z) in space. This work presents a Bayesian approach to estimate these parameters. A prior distribution of Z based on literature serves to overcome the biologically implausible Z estimates that can result from frequentist approaches. In addition to the classical estimation of a single P0 over the spawning area, the Bayesian framework allows also the modelling of egg densities in space, by including either spatial random effects, smoothing functions, or kriging like models, providing insights into the spatial variability of P0. The Bayesian approach was applied to the Bay of Biscay anchovy DEPM surveys. Results showed that this Bayesian approximation solved the implausible Z problem resulting in tighter credible intervals of both P0 and Z. Overall, spatial models outperformed the non-spatial model in terms of goodness of fit and resulted in slightly different total production estimates across models for each year, with a moderate decrease on uncertainty estimates.
加拿大渔业和水产科学杂志》（Canadian Journal of Fisheries and Aquatic Sciences），打印前。 用日产卵量法（DEPM）估算鱼类资源的生物量对日产卵量（P0）和卵死亡率（Z）在空间上的高变异性很敏感。本研究提出了一种贝叶斯方法来估算这些参数。基于文献的 Z 先验分布可克服频数法可能导致的生物学上难以置信的 Z 估计值。除了对产卵区单一 P0 的经典估算外，贝叶斯框架还可以通过空间随机效应、平滑函数或类似克里金模型，对空间中的卵密度进行建模，从而深入了解 P0 的空间变异性。贝叶斯方法被应用于比斯开湾鳀鱼 DEPM 调查。结果表明，这种贝叶斯近似方法解决了不可信的 Z 问题，使 P0 和 Z 的可信区间更窄。总体而言，空间模型在拟合优度方面优于非空间模型，各模型每年的总产量估计值略有不同，不确定性估计值适度下降。
{"title":"A Bayesian spatially explicit estimation of daily egg production: application to anchovy in the Bay of Biscay","authors":"Leire Citores, Leire Ibaibarriaga, Maria Santos, Andres Uriarte","doi":"10.1139/cjfas-2023-0126","DOIUrl":"https://doi.org/10.1139/cjfas-2023-0126","url":null,"abstract":"Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. <br/> Biomass estimates of fish resources by the daily egg production method (DEPM) are sensitive to the high variability of the daily egg production (P0) and egg mortality (Z) in space. This work presents a Bayesian approach to estimate these parameters. A prior distribution of Z based on literature serves to overcome the biologically implausible Z estimates that can result from frequentist approaches. In addition to the classical estimation of a single P0 over the spawning area, the Bayesian framework allows also the modelling of egg densities in space, by including either spatial random effects, smoothing functions, or kriging like models, providing insights into the spatial variability of P0. The Bayesian approach was applied to the Bay of Biscay anchovy DEPM surveys. Results showed that this Bayesian approximation solved the implausible Z problem resulting in tighter credible intervals of both P0 and Z. Overall, spatial models outperformed the non-spatial model in terms of goodness of fit and resulted in slightly different total production estimates across models for each year, with a moderate decrease on uncertainty estimates.","PeriodicalId":9515,"journal":{"name":"Canadian Journal of Fisheries and Aquatic Sciences","volume":"12 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139657745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eric R. Huber, Rachael E. Ryan, Rachel C. Johnson, Anna M. Sturrock, Robert A. Lusardi, Stephanie M. Carlson
Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. The California Central Valley steelhead (Oncorhynchus mykiss) has declined precipitously since Euro-American colonization and has been listed as threatened under the United States Endangered Species Act since 1998. Hatchery-origin fish now dominate the population, and hatchery management is a key listing factor. However, scant release metric information is available. We compiled a time series of O. mykiss hatchery release data for all four Central Valley hatcheries releasing O. mykiss between 1948 and 2017. The biocomplexity of released fish has declined since the early 1980s. Individuals have been released at increasingly similar numbers, biomass, body sizes, times, and locations over time. Moreover, yearling fish have been released at larger sizes, leading to the near-exclusive release of age-1 smolts in February and March since the late 1990s and early 2000s. Pervasive reductions in release portfolios have likely occurred for other hatchery-supported Pacific salmonid stocks throughout the Pacific Rim region. In an increasingly variable environment, such reductions in intraspecific diversity could significantly affect population stability and resilience.
{"title":"Seventy years of diminishing biocomplexity of California Central Valley hatchery steelhead, Oncorhynchus mykiss","authors":"Eric R. Huber, Rachael E. Ryan, Rachel C. Johnson, Anna M. Sturrock, Robert A. Lusardi, Stephanie M. Carlson","doi":"10.1139/cjfas-2023-0077","DOIUrl":"https://doi.org/10.1139/cjfas-2023-0077","url":null,"abstract":"Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. <br/> The California Central Valley steelhead (Oncorhynchus mykiss) has declined precipitously since Euro-American colonization and has been listed as threatened under the United States Endangered Species Act since 1998. Hatchery-origin fish now dominate the population, and hatchery management is a key listing factor. However, scant release metric information is available. We compiled a time series of O. mykiss hatchery release data for all four Central Valley hatcheries releasing O. mykiss between 1948 and 2017. The biocomplexity of released fish has declined since the early 1980s. Individuals have been released at increasingly similar numbers, biomass, body sizes, times, and locations over time. Moreover, yearling fish have been released at larger sizes, leading to the near-exclusive release of age-1 smolts in February and March since the late 1990s and early 2000s. Pervasive reductions in release portfolios have likely occurred for other hatchery-supported Pacific salmonid stocks throughout the Pacific Rim region. In an increasingly variable environment, such reductions in intraspecific diversity could significantly affect population stability and resilience.","PeriodicalId":9515,"journal":{"name":"Canadian Journal of Fisheries and Aquatic Sciences","volume":"23 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139657754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jamie C. Madden, Luc LaRochelle, Declan Burton, Sascha C. Danylchuk, Andy J. Danylchuk, Steven J. Cooke
Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. Without sufficient time to diffuse air from their swim bladders, physoclistous fish caught in deep water can exhibit symptoms of barotrauma. In this study, we tested the effectiveness of four barotrauma relief techniques on 76 walleye (Sander vitreus) and compared their 10 min post-release behaviour and depth selection with an untreated control group using a biologger containing a tri-axial accelerometer and depth sensor. Vented fish showed the best success rate of returning to depth, while no untreated controls were able to swim down. For fish that remained at depth, half were found to have lost orientation and were upside down during the entire monitoring period, with this orientation being strongly associated with the relief method. Vented fish had higher chances (80%) of remaining in the correct orientation at depth compared with the other methods (average of 38%). Our research shows that the best way to prevent negative outcomes of barotrauma is to avoid fishing at depths that yield barotrauma; however, if unavoidable, affected fish should be carefully vented by trained anglers to best reduce post-release impairments.
{"title":"Biologgers reveal unanticipated issues with descending angled walleye with barotrauma symptoms","authors":"Jamie C. Madden, Luc LaRochelle, Declan Burton, Sascha C. Danylchuk, Andy J. Danylchuk, Steven J. Cooke","doi":"10.1139/cjfas-2023-0141","DOIUrl":"https://doi.org/10.1139/cjfas-2023-0141","url":null,"abstract":"Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. <br/> Without sufficient time to diffuse air from their swim bladders, physoclistous fish caught in deep water can exhibit symptoms of barotrauma. In this study, we tested the effectiveness of four barotrauma relief techniques on 76 walleye (Sander vitreus) and compared their 10 min post-release behaviour and depth selection with an untreated control group using a biologger containing a tri-axial accelerometer and depth sensor. Vented fish showed the best success rate of returning to depth, while no untreated controls were able to swim down. For fish that remained at depth, half were found to have lost orientation and were upside down during the entire monitoring period, with this orientation being strongly associated with the relief method. Vented fish had higher chances (80%) of remaining in the correct orientation at depth compared with the other methods (average of 38%). Our research shows that the best way to prevent negative outcomes of barotrauma is to avoid fishing at depths that yield barotrauma; however, if unavoidable, affected fish should be carefully vented by trained anglers to best reduce post-release impairments.","PeriodicalId":9515,"journal":{"name":"Canadian Journal of Fisheries and Aquatic Sciences","volume":"53 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139412439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Bareille, M. Vignon, A. Chappaz, A. Fontaine, H. Tabouret, F. Morat, J. Martin, J.C. Aymes, F. Daverat, C. Pécheyran, O. Donard
Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. Using strontium (Sr) and barium (Ba) in otoliths to determine natal origins and understand patterns of fish movements is based on the fundamental assumption that otoliths record water chemistry signals without any major alterations. Although prior studies highlighted that fish physiology can modify the water signal in otoliths, studies for freshwater fish are scarce. We exposed different groups of Atlantic salmon parr Salmo salar to different scenarios of ambient-level variations in Sr/Ca and Ba/Ca ratios and then combined otolith chemical profiles with environmental data (water chemistry and temperature), Fulton's index, and otolith growth rates to assess what factors explain/influence the elemental ratios of Sr and Ba in otoliths. Generalized additive mixed models (GAMMs) using water-based otolith composition, temperature, Fulton's index, and “individual” as explanatory variables allow to demonstrate that water chemistry alone cannot fully explain measured ratios in otoliths, except in scenarios involving significant changes in water chemistry. Other factors (physiological effects) should be accounted for reproducing short and minimal seasonal variations in water composition, considering that inter-individual variability contributes quite significantly in most scenarios.
加拿大渔业与水产科学杂志》，提前出版。 利用耳石中的锶（Sr）和钡（Ba）来确定鱼类的产地并了解鱼类的运动模式是基于一个基本假设，即耳石记录的水化学信号不会发生任何重大改变。尽管之前的研究强调鱼类的生理机能会改变耳石中的水信号，但针对淡水鱼类的研究却很少。我们将不同组别的大西洋鲑小鲤鱼暴露于 Sr/Ca 和 Ba/Ca 比率环境水平变化的不同情景中，然后将耳石化学剖面与环境数据（水化学和温度）、富尔顿指数和耳石生长率相结合，以评估哪些因素可以解释/影响耳石中的 Sr 和 Ba 元素比率。使用水基耳石成分、温度、富尔顿指数和 "个体 "作为解释变量的广义加法混合模型（GAMMs）可以证明，除了在水化学发生重大变化的情况下，水化学本身并不能完全解释耳石中的测量比率。考虑到个体间的变化在大多数情况下都有相当大的影响，因此在再现水成分的短期和最小季节变化时，应考虑其他因素（生理效应）。
{"title":"Freshwater fish otoliths record signals from both water and physiological processes: new insights from Sr/Ca and Ba/Ca ratios","authors":"G. Bareille, M. Vignon, A. Chappaz, A. Fontaine, H. Tabouret, F. Morat, J. Martin, J.C. Aymes, F. Daverat, C. Pécheyran, O. Donard","doi":"10.1139/cjfas-2022-0030","DOIUrl":"https://doi.org/10.1139/cjfas-2022-0030","url":null,"abstract":"Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print. <br/> Using strontium (Sr) and barium (Ba) in otoliths to determine natal origins and understand patterns of fish movements is based on the fundamental assumption that otoliths record water chemistry signals without any major alterations. Although prior studies highlighted that fish physiology can modify the water signal in otoliths, studies for freshwater fish are scarce. We exposed different groups of Atlantic salmon parr Salmo salar to different scenarios of ambient-level variations in Sr/Ca and Ba/Ca ratios and then combined otolith chemical profiles with environmental data (water chemistry and temperature), Fulton's index, and otolith growth rates to assess what factors explain/influence the elemental ratios of Sr and Ba in otoliths. Generalized additive mixed models (GAMMs) using water-based otolith composition, temperature, Fulton's index, and “individual” as explanatory variables allow to demonstrate that water chemistry alone cannot fully explain measured ratios in otoliths, except in scenarios involving significant changes in water chemistry. Other factors (physiological effects) should be accounted for reproducing short and minimal seasonal variations in water composition, considering that inter-individual variability contributes quite significantly in most scenarios.","PeriodicalId":9515,"journal":{"name":"Canadian Journal of Fisheries and Aquatic Sciences","volume":"212 4 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139376362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accurate and precise estimates of survey abundance indices are essential inputs for stock assessment models therefore are important for the successful conservation and management of fisheries stocks. Since abundance indices can be standardized by various different ways from conventional design-based approaches to model-based approaches, it is essential to compare the efficiency of those approaches and quantify the consequences for stock assessments. In this study, we focus on an important commercial stock of witch flounder (Glyptocephalus cynoglossus) in NAFO 3N+3O divisions. We first compare the survey indices standardized by design-based and model-based approaches, and find that a model-based estimator provides more precise estimates of survey indices than design-based approach for this stock. We then apply a widely used Age-structured Statistical Catch-at-Length (ACL) assessment model to the standardized catch-at-length survey indices from both approaches to estimate the age-based population dynamics for this stock. We conclude that the ACL model fit to model-based indices performed better than the same model fit to design-based indices.
{"title":"Spatiotemporal model improves survey indices for witch flounder stock assessment in the Grand Banks","authors":"Jiaying Chen, Jinrong Gao, Fan Zhang","doi":"10.1139/cjfas-2023-0101","DOIUrl":"https://doi.org/10.1139/cjfas-2023-0101","url":null,"abstract":"Accurate and precise estimates of survey abundance indices are essential inputs for stock assessment models therefore are important for the successful conservation and management of fisheries stocks. Since abundance indices can be standardized by various different ways from conventional design-based approaches to model-based approaches, it is essential to compare the efficiency of those approaches and quantify the consequences for stock assessments. In this study, we focus on an important commercial stock of witch flounder (Glyptocephalus cynoglossus) in NAFO 3N+3O divisions. We first compare the survey indices standardized by design-based and model-based approaches, and find that a model-based estimator provides more precise estimates of survey indices than design-based approach for this stock. We then apply a widely used Age-structured Statistical Catch-at-Length (ACL) assessment model to the standardized catch-at-length survey indices from both approaches to estimate the age-based population dynamics for this stock. We conclude that the ACL model fit to model-based indices performed better than the same model fit to design-based indices.","PeriodicalId":9515,"journal":{"name":"Canadian Journal of Fisheries and Aquatic Sciences","volume":"52 29","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139442140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Morteza Eighani, T. Malta, Valentina Melli, Finbarr G. O’Neill
In this study, we investigate whether replacing conventional seabed-contacting otter boards with semi-pelagic self-adjusting otter boards (SAO), which have the ability to maintain a given height above the seabed, affects catch efficiency of a demersal fish trawl. Experimental fishing trials, using the alternate haul method, were conducted in the Kattegat and Skagerrak with three otter board configurations using: conventional seabed-contacting otter boards; the SAO set to maintain a target height over the seabed of 1 m; and the SAO set to maintain a target height 5 m. Replacing conventional otter boards with SAO resulted in a loss of catch efficiency for haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), and plaice (Hippoglossoides platessoides), while no significant difference was found for cod (Gadus morhua), common dab (Limanda limanda) and lemon sole (Microstomus kitt). When comparing the SAO - 1m and SAO - 5m, it was observed that SAO - 5m resulted in a loss of catch efficiency for haddock and plaice, a minimal reduction for cod and no significant difference for whiting, common dab, and lemon sole.
{"title":"Semi-pelagic self-adjusting otter boards: effects on the catching performance of a demersal trawl","authors":"Morteza Eighani, T. Malta, Valentina Melli, Finbarr G. O’Neill","doi":"10.1139/cjfas-2023-0224","DOIUrl":"https://doi.org/10.1139/cjfas-2023-0224","url":null,"abstract":"In this study, we investigate whether replacing conventional seabed-contacting otter boards with semi-pelagic self-adjusting otter boards (SAO), which have the ability to maintain a given height above the seabed, affects catch efficiency of a demersal fish trawl. Experimental fishing trials, using the alternate haul method, were conducted in the Kattegat and Skagerrak with three otter board configurations using: conventional seabed-contacting otter boards; the SAO set to maintain a target height over the seabed of 1 m; and the SAO set to maintain a target height 5 m. Replacing conventional otter boards with SAO resulted in a loss of catch efficiency for haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), and plaice (Hippoglossoides platessoides), while no significant difference was found for cod (Gadus morhua), common dab (Limanda limanda) and lemon sole (Microstomus kitt). When comparing the SAO - 1m and SAO - 5m, it was observed that SAO - 5m resulted in a loss of catch efficiency for haddock and plaice, a minimal reduction for cod and no significant difference for whiting, common dab, and lemon sole.","PeriodicalId":9515,"journal":{"name":"Canadian Journal of Fisheries and Aquatic Sciences","volume":"4 6","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139443874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Despite management efforts, like the implementation of escape panels and openings, unwanted catch remains a challenge in demersal trawl fisheries. Studies report that selectivity in escape panels and openings can be low. We explore the selective potential of a large escape opening placed in the aft of the trawl. We then examine if adding a dark tunnel behind the escape opening can increase the escape efficiency of fish by triggering a station-holding behavior. Our results showed limited escapement through the large escape opening, however, significant for narrow length ranges of some species. Adding the dark tunnel significantly increased the escapement for all analysed species, with escapement up to 70 (40-83)% and 63 (8-93)% for roundfish and flatfish, respectively. As target species, a loss of crustaceans up to 85 (60-96)% highlighted the importance of optimising the integration of the dark tunnel in demersal trawls. Providing the dark tunnel is integrated correctly, our results suggest that currently implemented escape panels and openings with low selective efficiency could be substantially improved by simple means like the dark tunnel.
{"title":"Improving escape efficiency in selective devices with the use of a dark tunnel","authors":"Mette Munkholm Svantemann, Esther Savina, L. Krag","doi":"10.1139/cjfas-2023-0232","DOIUrl":"https://doi.org/10.1139/cjfas-2023-0232","url":null,"abstract":"Despite management efforts, like the implementation of escape panels and openings, unwanted catch remains a challenge in demersal trawl fisheries. Studies report that selectivity in escape panels and openings can be low. We explore the selective potential of a large escape opening placed in the aft of the trawl. We then examine if adding a dark tunnel behind the escape opening can increase the escape efficiency of fish by triggering a station-holding behavior. Our results showed limited escapement through the large escape opening, however, significant for narrow length ranges of some species. Adding the dark tunnel significantly increased the escapement for all analysed species, with escapement up to 70 (40-83)% and 63 (8-93)% for roundfish and flatfish, respectively. As target species, a loss of crustaceans up to 85 (60-96)% highlighted the importance of optimising the integration of the dark tunnel in demersal trawls. Providing the dark tunnel is integrated correctly, our results suggest that currently implemented escape panels and openings with low selective efficiency could be substantially improved by simple means like the dark tunnel.","PeriodicalId":9515,"journal":{"name":"Canadian Journal of Fisheries and Aquatic Sciences","volume":"37 31","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139443013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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