Tianjiao Zhang, Hu Guo, Liming Song, Hongchun Yuan, Hengshou Sui, Bin Li
This study aims to find reliable vertical environmental variables for modeling the fishing grounds of albacore (Thunnus alalunga) in the tropical waters of the Atlantic Ocean. Logbook data of 13 Chinese longliners operating in the high seas of the Atlantic Ocean from 2016 to 2019 were collected and matched with vertical environmental variables including dissolved oxygen, temperature, and salinity from 0 to 500 m at 50‐m depth intervals. Then four machine learning (ML) models: decision tree (DT), random forest (RF), light gradient boosting (LGB) and categorical boosting (CGB) were constructed and compared with generalized additive models (GAMs) within spatial resolutions of .5° × .5°, 1° × 1°, and 2° × 2° grids to find the significant features. The importance of each variable was ranked and compared based on Shapley additive explanations (SHAP) approach across five ML models at three resolutions. Results showed that (1) the vertical environmental variables—temperature at the depth of 100 m and dissolved oxygen concentration at the depth of 100 and 150 m—were the significant features that contributed most to all the ML models at three spatial resolutions; (2) the models with a spatial resolution of 2° × 2° grid exhibited higher accuracy compared to the models with .5° × .5° and 1° × 1° grids; (3) the RF model had the best prediction performance among all the models tested. Our results suggested that significant vertical environmental variables showed similar importance across different ML models at different resolutions, and these specific variables can be relied upon for accurately predicting the fishing grounds of albacore in the tropical waters of the Atlantic Ocean.
{"title":"Evaluating the importance of vertical environmental variables for albacore fishing grounds in tropical Atlantic Ocean using machine learning and Shapley additive explanations (SHAP) approach","authors":"Tianjiao Zhang, Hu Guo, Liming Song, Hongchun Yuan, Hengshou Sui, Bin Li","doi":"10.1111/fog.12701","DOIUrl":"https://doi.org/10.1111/fog.12701","url":null,"abstract":"This study aims to find reliable vertical environmental variables for modeling the fishing grounds of albacore (<jats:styled-content style=\"fixed-case\"><jats:italic>Thunnus alalunga</jats:italic></jats:styled-content>) in the tropical waters of the Atlantic Ocean. Logbook data of 13 Chinese longliners operating in the high seas of the Atlantic Ocean from 2016 to 2019 were collected and matched with vertical environmental variables including dissolved oxygen, temperature, and salinity from 0 to 500 m at 50‐m depth intervals. Then four machine learning (ML) models: decision tree (DT), random forest (RF), light gradient boosting (LGB) and categorical boosting (CGB) were constructed and compared with generalized additive models (GAMs) within spatial resolutions of .5° × .5°, 1° × 1°, and 2° × 2° grids to find the significant features. The importance of each variable was ranked and compared based on Shapley additive explanations (SHAP) approach across five ML models at three resolutions. Results showed that (1) the vertical environmental variables—temperature at the depth of 100 m and dissolved oxygen concentration at the depth of 100 and 150 m—were the significant features that contributed most to all the ML models at three spatial resolutions; (2) the models with a spatial resolution of 2° × 2° grid exhibited higher accuracy compared to the models with .5° × .5° and 1° × 1° grids; (3) the RF model had the best prediction performance among all the models tested. Our results suggested that significant vertical environmental variables showed similar importance across different ML models at different resolutions, and these specific variables can be relied upon for accurately predicting the fishing grounds of albacore in the tropical waters of the Atlantic Ocean.","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208267","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}
Warsha Singh, Kristinn Guðnason, Marcel Montanyès, Martin Lindegren
Climate change is altering the distribution of marine organisms worldwide. This may, in turn, affect the overall structure and functioning of ecosystems, sometimes leading to low productive regimes. Pronounced shifts in distribution and migration have been observed for capelin (Mallotus villosus), one of the ecologically and commercially important species in the Arctic. This study attempts to discern whether a relationship existed between the altered capelin dynamics and the changing physical environmental conditions in the Iceland‐East Greenland‐Jan Mayen region. More specifically, three species distribution models were used to predict hindcasts (pre‐shift years 1993–2002) and nowcasts (post‐shift years 2003–2019) of capelin distribution based on relationships with temperature, salinity, current speed, net primary productivity, and bathymetry. The predicted probability of occurrence over these two time periods demonstrates that the changing environmental conditions have contributed to the modified distribution of the stock during its late feeding season in autumn and during the onset of spawning season in winter. The multi‐model approach used in this study has provided a solid statistical framework to describe the environmental niche of capelin and its potential responses to changing ocean climate.
{"title":"Climate driven response of the Iceland‐East Greenland‐Jan Mayen capelin distribution","authors":"Warsha Singh, Kristinn Guðnason, Marcel Montanyès, Martin Lindegren","doi":"10.1111/fog.12702","DOIUrl":"https://doi.org/10.1111/fog.12702","url":null,"abstract":"Climate change is altering the distribution of marine organisms worldwide. This may, in turn, affect the overall structure and functioning of ecosystems, sometimes leading to low productive regimes. Pronounced shifts in distribution and migration have been observed for capelin (<jats:styled-content style=\"fixed-case\"><jats:italic>Mallotus villosus</jats:italic></jats:styled-content>), one of the ecologically and commercially important species in the Arctic. This study attempts to discern whether a relationship existed between the altered capelin dynamics and the changing physical environmental conditions in the Iceland‐East Greenland‐Jan Mayen region. More specifically, three species distribution models were used to predict hindcasts (pre‐shift years 1993–2002) and nowcasts (post‐shift years 2003–2019) of capelin distribution based on relationships with temperature, salinity, current speed, net primary productivity, and bathymetry. The predicted probability of occurrence over these two time periods demonstrates that the changing environmental conditions have contributed to the modified distribution of the stock during its late feeding season in autumn and during the onset of spawning season in winter. The multi‐model approach used in this study has provided a solid statistical framework to describe the environmental niche of capelin and its potential responses to changing ocean climate.","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208268","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}
Gut contents and nitrogen isotope ratio (δ15N) analyses were conducted on splendid alfonsino Beryx splendens collected in the vicinity of Kuroshio from May 2015 to November 2016 (n = 708) to identify their feeding habits in the Western North Pacific. Micronektonic fish, shrimp, and squid were the dominant prey species, with the Decapoda Acanthephyra quadrispinosa, Prehensilosergia prehensilis, Cephalopoda Enoploteuthis chunii, Chiroteuthis calyx, Teleostei Sigmops gracilis, and Gonostoma elongatum. These micronektons are common in the Kuroshio Current; thus, B. splendens is a possible opportunistic feeder. Gut content weight (GCW), occurrence (%O) of fish and squid, and δ15N were significantly increased with the fork length (FL) of B. splendens. Only the %O of shrimp does not show a significant relationship with the FL of B. splendens. These indicated the ontogenetic shift of dominant prey from shrimp to fish. Fattened specimens could also prey on a greater number of fish. The seasonality of GCW and %O values was high in spring and autumn and low in summer and winter. This seasonality indicated that the feeding habits of B. splendens are controlled by primary productivity in the surface layer and/or by maturity. When the Kuroshio flowed in the north of Hachijojima Island, the GCW was significantly increased, and some organisms, including C. calyx, G. elongatum, and S. gracilis, were preyed on more. While the offshore area of the Kuroshio has low productivity, B. splendens can actively prey in this area, indicating that it is an important feeding ground for this species.
{"title":"Feeding habits of splendid alfonsino Beryx splendens in the vicinity of Kuroshio, the south of Japan","authors":"Taketoshi Kodama, Koichi Ishii, Sachiko Horii, Natsuki Gonda, Junji Yonezawa, Kazuto Ando, Kazutaka Takahashi","doi":"10.1111/fog.12703","DOIUrl":"https://doi.org/10.1111/fog.12703","url":null,"abstract":"Gut contents and nitrogen isotope ratio (<jats:italic>δ</jats:italic><jats:sup>15</jats:sup>N) analyses were conducted on splendid alfonsino <jats:styled-content style=\"fixed-case\"><jats:italic>Beryx splendens</jats:italic></jats:styled-content> collected in the vicinity of Kuroshio from May 2015 to November 2016 (<jats:italic>n</jats:italic> = 708) to identify their feeding habits in the Western North Pacific. Micronektonic fish, shrimp, and squid were the dominant prey species, with the Decapoda <jats:styled-content style=\"fixed-case\"><jats:italic>Acanthephyra quadrispinosa</jats:italic></jats:styled-content>, <jats:italic>Prehensilosergia prehensilis</jats:italic>, Cephalopoda <jats:styled-content style=\"fixed-case\"><jats:italic>Enoploteuthis chunii</jats:italic></jats:styled-content>, <jats:styled-content style=\"fixed-case\"><jats:italic>Chiroteuthis calyx</jats:italic></jats:styled-content>, Teleostei <jats:styled-content style=\"fixed-case\"><jats:italic>Sigmops gracilis</jats:italic></jats:styled-content>, and <jats:styled-content style=\"fixed-case\"><jats:italic>Gonostoma elongatum</jats:italic></jats:styled-content>. These micronektons are common in the Kuroshio Current; thus, <jats:styled-content style=\"fixed-case\"><jats:italic>B. splendens</jats:italic></jats:styled-content> is a possible opportunistic feeder. Gut content weight (GCW), occurrence (%O) of fish and squid, and <jats:italic>δ</jats:italic><jats:sup>15</jats:sup>N were significantly increased with the fork length (FL) of <jats:styled-content style=\"fixed-case\"><jats:italic>B. splendens</jats:italic></jats:styled-content>. Only the %O of shrimp does not show a significant relationship with the FL of <jats:styled-content style=\"fixed-case\"><jats:italic>B. splendens</jats:italic></jats:styled-content>. These indicated the ontogenetic shift of dominant prey from shrimp to fish. Fattened specimens could also prey on a greater number of fish. The seasonality of GCW and %O values was high in spring and autumn and low in summer and winter. This seasonality indicated that the feeding habits of <jats:styled-content style=\"fixed-case\"><jats:italic>B. splendens</jats:italic></jats:styled-content> are controlled by primary productivity in the surface layer and/or by maturity. When the Kuroshio flowed in the north of Hachijojima Island, the GCW was significantly increased, and some organisms, including <jats:styled-content style=\"fixed-case\"><jats:italic>C. calyx</jats:italic></jats:styled-content>, <jats:styled-content style=\"fixed-case\"><jats:italic>G. elongatum</jats:italic></jats:styled-content>, and <jats:styled-content style=\"fixed-case\"><jats:italic>S. gracilis</jats:italic></jats:styled-content>, were preyed on more. While the offshore area of the Kuroshio has low productivity, <jats:styled-content style=\"fixed-case\"><jats:italic>B. splendens</jats:italic></jats:styled-content> can actively prey in this area, indicating that it is an important feeding ground for this species.","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208271","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}
Trace element analysis of otoliths from core to edge was used to reveal differences in habitats of larvae and early juveniles of Japanese jack mackerel (Trachurus japonicus) caught in the East China Sea (ECS), Pacific Ocean, and Sea of Japan. Multi‐element signatures (Sr:Ca, Mg:Ca, Na:Ca, K:Ca, and Ba:Ca) were analyzed with multivariate statistics to determine whether these element signatures provide insight into regional population structure. The median values of elements: Ca ratios in otolith core region differed significantly among areas, with most elements between the ECS and the Pacific Ocean or Sea of Japan showing significant differences. The Sr:Ca ratios exhibited a V‐shaped trend from the otolith core to the edge, which was likely related to the vertical habitat layer shift of larvae and early juveniles of T. japonicus. Canonical analysis of principal coordinates using the element: Ca ratios and the hatching day were re‐classified according to the sampling area with higher accuracy in the ECS (88–95%) and the Sea of Japan (76–83%) compared to the Pacific Ocean (69–72%). These results indicate that the proportion of eggs, larvae, and early juveniles transported by the Kuroshio Current from the southern ECS—the main spawning ground—to the Pacific Ocean or the Sea of Japan is low and that juveniles distributed in the coastal waters off southwestern Japan may have originated from local spawners. These results suggest that determining the elemental composition of larvae and juveniles of T. japonicus is effective in determining the habitat differences of this species in the three regions. These findings will help to understand population structure and recruitment process of this species around Japan.
利用对耳石从核心到边缘的微量元素分析，揭示了在中国东海（ECS）、太平洋和日本海捕获的日本竹筴鱼（Trachurus japonicus）幼鱼和早期幼鱼栖息地的差异。多元素特征（Sr:Ca、Mg:Ca、Na:Ca、K:Ca 和 Ba:Ca）通过多元统计进行分析，以确定这些元素特征是否有助于了解区域种群结构。元素的中位值为耳石核心区域的元素：Ca 比率中值在不同区域之间存在显著差异，其中大多数元素在东大陆架与太平洋或日本海之间存在显著差异。从耳石核心到边缘，Sr:Ca比值呈V形变化趋势，这可能与日本栉水母幼体和早期幼体的垂直生境层转移有关。使用元素对主坐标进行典型分析：与太平洋（69-72%）相比，ECS（88-95%）和日本海（76-83%）根据采样区域对 Ca 比值和孵化日进行重新分类的准确率更高。这些结果表明，黑潮将卵、幼体和早期幼体从南部 ECS（主要产卵场）运到太平洋或日本海的比例很低，分布在日本西南部近海的幼体可能来自当地的产卵者。这些结果表明，测定日本栉水母幼体和幼鱼的元素组成可以有效地确定该物种在三个地区的栖息地差异。这些发现将有助于了解该物种在日本各地的种群结构和招募过程。
{"title":"Otolith elemental composition indicates differences in the habitat use for larvae and early juveniles of Japanese jack mackerel (Trachurus japonicus) in the waters around Japan","authors":"Yuki Fujinami, Motomitsu Takahashi, Chiyuki Sassa, Yuko Hiraoka, Hiroyuki Kurota, Seiji Ohshimo","doi":"10.1111/fog.12699","DOIUrl":"https://doi.org/10.1111/fog.12699","url":null,"abstract":"Trace element analysis of otoliths from core to edge was used to reveal differences in habitats of larvae and early juveniles of Japanese jack mackerel (<jats:styled-content style=\"fixed-case\"><jats:italic>Trachurus japonicus</jats:italic></jats:styled-content>) caught in the East China Sea (ECS), Pacific Ocean, and Sea of Japan. Multi‐element signatures (Sr:Ca, Mg:Ca, Na:Ca, K:Ca, and Ba:Ca) were analyzed with multivariate statistics to determine whether these element signatures provide insight into regional population structure. The median values of elements: Ca ratios in otolith core region differed significantly among areas, with most elements between the ECS and the Pacific Ocean or Sea of Japan showing significant differences. The Sr:Ca ratios exhibited a V‐shaped trend from the otolith core to the edge, which was likely related to the vertical habitat layer shift of larvae and early juveniles of <jats:styled-content style=\"fixed-case\"><jats:italic>T. japonicus</jats:italic></jats:styled-content>. Canonical analysis of principal coordinates using the element: Ca ratios and the hatching day were re‐classified according to the sampling area with higher accuracy in the ECS (88–95%) and the Sea of Japan (76–83%) compared to the Pacific Ocean (69–72%). These results indicate that the proportion of eggs, larvae, and early juveniles transported by the Kuroshio Current from the southern ECS—the main spawning ground—to the Pacific Ocean or the Sea of Japan is low and that juveniles distributed in the coastal waters off southwestern Japan may have originated from local spawners. These results suggest that determining the elemental composition of larvae and juveniles of <jats:styled-content style=\"fixed-case\"><jats:italic>T. japonicus</jats:italic></jats:styled-content> is effective in determining the habitat differences of this species in the three regions. These findings will help to understand population structure and recruitment process of this species around Japan.","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208269","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}
Erling Kåre Stenevik, Svein Sundby, Bjørn Ådlandsvik, Anders Thorsen
Vertical egg distributions are needed knowledge for understanding exposure to physical forcing, predation pressure, and modelling initial transport from the spawning areas. Egg density and size are the biotic factors determining vertical distributions while the ambient salinity and turbulent mixing are the physical factors contributing to their vertical distributions. Egg buoyancies and densities of Atlantic cod (Gadus morhua) have been extensively studied, while limited information on haddock (Melanogrammus aeglefinus) egg density is available. This is the first comprehensive study on haddock egg densities in Norwegian waters. Eggs were collected from pairs of spawning fish caught at the coast of western Norway and inserted into a density gradient column where density was measured. The haddock eggs were neutrally buoyant at salinities ranging from 28.5 to 31. The density changed during egg development, and the results from the measurements were used to model the vertical distribution of the eggs. The simulations showed that the changes in buoyancy substantially affected vertical distributions. A comparison to previously published data on cod eggs showed that haddock eggs are considerably more buoyant than the cod eggs and are—particularly during calm wind conditions—confined to the surface layer to a larger extent than the cod eggs. The more buoyant attribute of the haddock eggs, together with the lipophilic surface of the egg membrane, is suggested to make haddock eggs more vulnerable to buoyant pollutants, like hydrocarbons.
{"title":"Buoyancy and vertical distribution of haddock (Melanogrammus aeglefinus) eggs during embryonic development: A comparison with cod (Gadus morhua)","authors":"Erling Kåre Stenevik, Svein Sundby, Bjørn Ådlandsvik, Anders Thorsen","doi":"10.1111/fog.12700","DOIUrl":"https://doi.org/10.1111/fog.12700","url":null,"abstract":"Vertical egg distributions are needed knowledge for understanding exposure to physical forcing, predation pressure, and modelling initial transport from the spawning areas. Egg density and size are the biotic factors determining vertical distributions while the ambient salinity and turbulent mixing are the physical factors contributing to their vertical distributions. Egg buoyancies and densities of Atlantic cod (<jats:styled-content style=\"fixed-case\"><jats:italic>Gadus morhua</jats:italic></jats:styled-content>) have been extensively studied, while limited information on haddock <jats:italic>(<jats:styled-content style=\"fixed-case\">Melanogrammus aeglefinus</jats:styled-content></jats:italic>) egg density is available. This is the first comprehensive study on haddock egg densities in Norwegian waters. Eggs were collected from pairs of spawning fish caught at the coast of western Norway and inserted into a density gradient column where density was measured. The haddock eggs were neutrally buoyant at salinities ranging from 28.5 to 31. The density changed during egg development, and the results from the measurements were used to model the vertical distribution of the eggs. The simulations showed that the changes in buoyancy substantially affected vertical distributions. A comparison to previously published data on cod eggs showed that haddock eggs are considerably more buoyant than the cod eggs and are—particularly during calm wind conditions—confined to the surface layer to a larger extent than the cod eggs. The more buoyant attribute of the haddock eggs, together with the lipophilic surface of the egg membrane, is suggested to make haddock eggs more vulnerable to buoyant pollutants, like hydrocarbons.","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208270","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}
Huidong Jiang, Zhenjiang Ye, Yixiao Zhang, Wenchao Zhang, Yongjun Tian, Jianchao Li, Yang Liu, Haiqing Yu, Xingui Zhang
Vertical migration and dispersal processes during the marine crab larval stage markedly affect transport, habitat selection, population connectivity, and resource replenishment success rates. However, not much is known of the reproductive ecology of swimming crabs in the nearshore waters of the northwest Pacific shelf. Here, we investigated the diel vertical migration (DVM) characteristics and transport patterns of the swimming crab zoea (Portunus trituberculatus) in this area. A Lagrangian particle‐tracking algorithm coupled with a hydrodynamic model, incorporating a DVM pattern of zoeae based on observations from a field survey of the diurnal distribution of swimming crab zoea, was used to simulate the transport of zoeae, and the impact of zoeal transport on population connectivity was explored. The results revealed that particles were predominantly transported in a nearshore direction from the particle release point, with short dispersal distances during the zoeal stages. In nearshore waters on the continental shelf, the swimming crab zoeae are exposed to shoreward‐moving currents with the aid of prolonged daytime locations in the lower water column, whereas larvae migrate upward to the middle and upper layers of the water column at night rather than the most superficial layer, potentially avoiding surface offshore‐moving currents that may be responsible for the retention and shoreward transport of larvae. Most zoeae are transported to shallow waters, and the contribution of transport to population connectivity during the zoeal stages is relatively limited. The findings here have considerable implications for understanding the mechanisms governing the early recruitment dynamics of this species, as well as for fisheries management and conservation of marine biodiversity.
{"title":"The integration of diel vertical migration and hydrodynamic process influences the transport of swimming crab zoea (Portunus trituberculatus)","authors":"Huidong Jiang, Zhenjiang Ye, Yixiao Zhang, Wenchao Zhang, Yongjun Tian, Jianchao Li, Yang Liu, Haiqing Yu, Xingui Zhang","doi":"10.1111/fog.12695","DOIUrl":"https://doi.org/10.1111/fog.12695","url":null,"abstract":"Vertical migration and dispersal processes during the marine crab larval stage markedly affect transport, habitat selection, population connectivity, and resource replenishment success rates. However, not much is known of the reproductive ecology of swimming crabs in the nearshore waters of the northwest Pacific shelf. Here, we investigated the diel vertical migration (DVM) characteristics and transport patterns of the swimming crab zoea (<jats:italic>Portunus trituberculatus</jats:italic>) in this area. A Lagrangian particle‐tracking algorithm coupled with a hydrodynamic model, incorporating a DVM pattern of zoeae based on observations from a field survey of the diurnal distribution of swimming crab zoea, was used to simulate the transport of zoeae, and the impact of zoeal transport on population connectivity was explored. The results revealed that particles were predominantly transported in a nearshore direction from the particle release point, with short dispersal distances during the zoeal stages. In nearshore waters on the continental shelf, the swimming crab zoeae are exposed to shoreward‐moving currents with the aid of prolonged daytime locations in the lower water column, whereas larvae migrate upward to the middle and upper layers of the water column at night rather than the most superficial layer, potentially avoiding surface offshore‐moving currents that may be responsible for the retention and shoreward transport of larvae. Most zoeae are transported to shallow waters, and the contribution of transport to population connectivity during the zoeal stages is relatively limited. The findings here have considerable implications for understanding the mechanisms governing the early recruitment dynamics of this species, as well as for fisheries management and conservation of marine biodiversity.","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208299","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. Sullaway, Curry J. Cunningham, David G Kimmel, Darren J. Pilcher, James T Thorson
Understanding how ecosystem change influences fishery resources through trophic pathways is a key tenet of ecosystem‐based fishery management. System models (SM), which use numerical modeling to describe physical and biological processes, can advance inclusion of ecosystem and prey information in fisheries management; however, incorporating SMs in management requires evaluation against empirical data. The Bering Ecosystem Study Nutrient‐Phytoplankton‐Zooplankton (BESTNPZ) model is an SM (originally created by the Bering Ecosystem Study, which initiated in 2006 and was expanded by Kearney et al.) includes zooplankton biomass hindcasts for the Bering Sea. In the Bering Sea, zooplankton are an important prey item for fishery species, yet the zooplankton component of this SM has not been validated against empirical data. We compared empirical zooplankton data to BESTNPZ hindcast estimates for three zooplankton functional groups and found that the two sources of information are on different absolute scales. We found high correlation between relative seasonal biomass trends estimated by BESTNPZ and empirical data for large off‐shelf copepods (Neocalanus spp.) and low correlations for large on‐shelf copepods and small copepods (Calanus spp. and Pseudocalanus spp., respectively). To address these discrepancies, we constructed hybrid species distribution models (H‐SDM), which predict zooplankton biomass using the BESTNPZ hindcast and environmental covariates. We found that H‐SDMs offered marginal improvements over correlative species distribution models (C‐SDMs) relying solely on empirical data for spatial extrapolation and little improvement for most functional groups when forecasting short‐term temporal zooplankton biomass trends. Overall, we suggest that interpretation of current BESTNPZ hindcasts should be tempered by our understanding of key mismatches in absolute scale, seasonality, and annual indices between BESTNPZ and empirical data.
{"title":"Evaluating the performance of a system model in predicting zooplankton dynamics: Insights from the Bering Sea ecosystem","authors":"G. Sullaway, Curry J. Cunningham, David G Kimmel, Darren J. Pilcher, James T Thorson","doi":"10.1111/fog.12691","DOIUrl":"https://doi.org/10.1111/fog.12691","url":null,"abstract":"Understanding how ecosystem change influences fishery resources through trophic pathways is a key tenet of ecosystem‐based fishery management. System models (SM), which use numerical modeling to describe physical and biological processes, can advance inclusion of ecosystem and prey information in fisheries management; however, incorporating SMs in management requires evaluation against empirical data. The Bering Ecosystem Study Nutrient‐Phytoplankton‐Zooplankton (BESTNPZ) model is an SM (originally created by the Bering Ecosystem Study, which initiated in 2006 and was expanded by Kearney et al.) includes zooplankton biomass hindcasts for the Bering Sea. In the Bering Sea, zooplankton are an important prey item for fishery species, yet the zooplankton component of this SM has not been validated against empirical data. We compared empirical zooplankton data to BESTNPZ hindcast estimates for three zooplankton functional groups and found that the two sources of information are on different absolute scales. We found high correlation between relative seasonal biomass trends estimated by BESTNPZ and empirical data for large off‐shelf copepods (Neocalanus spp.) and low correlations for large on‐shelf copepods and small copepods (Calanus spp. and Pseudocalanus spp., respectively). To address these discrepancies, we constructed hybrid species distribution models (H‐SDM), which predict zooplankton biomass using the BESTNPZ hindcast and environmental covariates. We found that H‐SDMs offered marginal improvements over correlative species distribution models (C‐SDMs) relying solely on empirical data for spatial extrapolation and little improvement for most functional groups when forecasting short‐term temporal zooplankton biomass trends. Overall, we suggest that interpretation of current BESTNPZ hindcasts should be tempered by our understanding of key mismatches in absolute scale, seasonality, and annual indices between BESTNPZ and empirical data.","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141920959","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}
For small pelagic fish, the physical and feeding environments during the larval and juvenile periods significantly affect recruitment to standing stock. To understand the variation in environmental conditions experienced by larvae and juveniles, this study determined the distribution of larval and juvenile Pacific saury Cololabis saira over a distance of more than 6900 km in an east–west direction in relation to the ocean environment in winter. Specimens were collected from the western and central parts of the North Pacific Ocean, mainly in January and February 2018 and 2020. Larvae (≤39.9 mm) were broadly distributed around the Kuroshio Current and the Kuroshio Extension Current. Larval densities in the water masses around the Kuroshio Extension Current were as high as, or even significantly higher than, those around the Kuroshio Current, which is considered the main spawning ground. Most juveniles (≥40.0 mm) were captured north of the Kuroshio Extension Current, where sea surface temperatures were lower and chlorophyll a concentrations were higher. The generalized additive model analysis also suggested that, compared to larvae, juveniles tended to be distributed in areas with lower sea surface temperatures and in more eastern areas. The extensive distribution of Pacific saury larvae and juveniles indicates that it is necessary to focus not only on the marine environment around the Kuroshio region but also on the Kuroshio Extension region to understand the recruitment variability of this species.
对于小型中上层鱼类而言，幼鱼和幼鱼时期的物理环境和觅食环境对常备种群的增殖有重大影响。为了解幼体和幼鱼所经历的环境条件变化，本研究测定了太平洋秋刀鱼（Cololabis saira）幼体和幼鱼在东西方向超过 6900 公里的分布与冬季海洋环境的关系。标本主要于2018年和2020年1月和2月在北太平洋西部和中部采集。幼体（≤39.9 毫米）广泛分布在黑潮和黑潮延伸流周围。黑潮延伸流附近水体中的幼体密度与黑潮附近的幼体密度相当，甚至明显高于黑潮附近的幼体密度，而黑潮附近被认为是主要的产卵场。大多数幼鱼（≥40.0 mm）在黑潮延伸流以北捕获，那里的海面温度较低，叶绿素 a 浓度较高。广义加性模型分析还表明，与幼体相比，幼体往往分布在海面温度较低的地区和东部地区。太平洋秋刀鱼幼体和幼鱼的广泛分布表明，不仅有必要关注黑潮区域周围的海洋环境，而且有必要关注黑潮延伸区域，以了解该物种的增殖变化。
{"title":"Distributions of larvae and juveniles of Pacific saury Cololabis saira during winter in relation to oceanographic structures in the central and western North Pacific Ocean","authors":"Fuji Taiki, Miyamoto Hiroomi, Abo Jun‐ichi, Watai Mikio","doi":"10.1111/fog.12697","DOIUrl":"https://doi.org/10.1111/fog.12697","url":null,"abstract":"For small pelagic fish, the physical and feeding environments during the larval and juvenile periods significantly affect recruitment to standing stock. To understand the variation in environmental conditions experienced by larvae and juveniles, this study determined the distribution of larval and juvenile Pacific saury Cololabis saira over a distance of more than 6900 km in an east–west direction in relation to the ocean environment in winter. Specimens were collected from the western and central parts of the North Pacific Ocean, mainly in January and February 2018 and 2020. Larvae (≤39.9 mm) were broadly distributed around the Kuroshio Current and the Kuroshio Extension Current. Larval densities in the water masses around the Kuroshio Extension Current were as high as, or even significantly higher than, those around the Kuroshio Current, which is considered the main spawning ground. Most juveniles (≥40.0 mm) were captured north of the Kuroshio Extension Current, where sea surface temperatures were lower and chlorophyll a concentrations were higher. The generalized additive model analysis also suggested that, compared to larvae, juveniles tended to be distributed in areas with lower sea surface temperatures and in more eastern areas. The extensive distribution of Pacific saury larvae and juveniles indicates that it is necessary to focus not only on the marine environment around the Kuroshio region but also on the Kuroshio Extension region to understand the recruitment variability of this species.","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925585","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}
After ocean entry, juvenile Japanese chum salmon migrate northeastward to the Sea of Okhotsk. However, some juveniles originating in rivers along the Pacific coast of Hokkaido were reported to migrate in the opposite direction (westward). We compiled historical data to determine which river‐origin juveniles migrate westward and to what extent. Then, the ocean‐entry conditions and growth rates of 398 juveniles from two rivers along the Pacific coast of Hokkaido were estimated with otolith daily‐increment analysis. Many juveniles migrated >100 km westward from multiple natal river mouths. Juveniles collected to the west of their natal rivers tended to enter the ocean earlier than those collected to the east, and many did so before sea surface temperatures reached 5°C (the lower limit of the empirically favorable temperature range). In the west, many small juveniles were collected soon after ocean entry, suggesting that they migrated passively with the Coastal Oyashio, a westward cold current. By contrast, juveniles collected in the east tended to grow faster in length and have a lower body condition factor at capture, possibly due to growth‐dependent mortality during their migration against the flow of the Coastal Oyashio. Moreover, many juveniles in the west were exposed to temperatures near 13°C (the upper limit of favorable temperatures) at capture. In recent years, there has been a shortening of the favorable water‐temperature period and a drastic decline in adult chum returns in the region. There is hence concern that the likelihood of abortive migrations for juveniles transported westward will increase.
{"title":"Characteristics of juvenile chum salmon carrying out inverse migrations after ocean entry from rivers along the Pacific coast of Hokkaido, Japan","authors":"Kentaro Honda, Kotaro Shirai, Takumi Morishita, Toshihiko Saito","doi":"10.1111/fog.12698","DOIUrl":"https://doi.org/10.1111/fog.12698","url":null,"abstract":"After ocean entry, juvenile Japanese chum salmon migrate northeastward to the Sea of Okhotsk. However, some juveniles originating in rivers along the Pacific coast of Hokkaido were reported to migrate in the opposite direction (westward). We compiled historical data to determine which river‐origin juveniles migrate westward and to what extent. Then, the ocean‐entry conditions and growth rates of 398 juveniles from two rivers along the Pacific coast of Hokkaido were estimated with otolith daily‐increment analysis. Many juveniles migrated >100 km westward from multiple natal river mouths. Juveniles collected to the west of their natal rivers tended to enter the ocean earlier than those collected to the east, and many did so before sea surface temperatures reached 5°C (the lower limit of the empirically favorable temperature range). In the west, many small juveniles were collected soon after ocean entry, suggesting that they migrated passively with the Coastal Oyashio, a westward cold current. By contrast, juveniles collected in the east tended to grow faster in length and have a lower body condition factor at capture, possibly due to growth‐dependent mortality during their migration against the flow of the Coastal Oyashio. Moreover, many juveniles in the west were exposed to temperatures near 13°C (the upper limit of favorable temperatures) at capture. In recent years, there has been a shortening of the favorable water‐temperature period and a drastic decline in adult chum returns in the region. There is hence concern that the likelihood of abortive migrations for juveniles transported westward will increase.","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141926994","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}
Brian E. Smith, Stefán Ragnarsson, Jeremy S. Collie
Continental shelves experience many human pressures with demersal fisheries central to disturbing the ocean floor. However, ecological processes such as predation rates of benthos and their relationship with bottom fishing are often unknown for large marine ecosystems. We examined the amount of benthos consumed by 14 benthivorous fishes, the overlap between benthos predation and bottom fishing (dredge and trawl gear), and temporal trends in benthivorous fish abundance and the number of fishing trips on the northeast US continental shelf. Mean annual predation (biomass of prey removed) and 95% confidence intervals ranged from .0002 (.0001–.0003) to 3967 (1761–7112) t per 10‐min area squared grid cell and prey taxa for these benthivorous fishes. Predation and bottom fishing had overlapping footprints of activity, which were slightly stronger for dredge gear. Trophic success (ratio of prey biomass eaten to the biomass of the benthivore community per grid cell) revealed more Bivalvia, Gammaridea, and Polychaeta eaten in areas targeted by trawling with more fish biomass. In contrast, dredging did not target fish biomass, but these areas had increased (Echinoidea, Gammaridea, and other benthos) or decreased (Ophiuroidea) trophic success relative to dredging footprint, suggesting habitat preferences for benthic prey and demersal fisheries have converged rather than diverged. Despite declines in bottom fishing, recent increases in benthivorous fish abundance and growing interest in ocean floor use suggest that fisheries managers should ensure benthivores have sufficient prey resources relative to their community size and human pressures to promote long‐term sustainability of demersal fisheries and healthy ecosystems.
{"title":"Quantifying predation on benthos and its overlap with bottom fishing in the NW Atlantic","authors":"Brian E. Smith, Stefán Ragnarsson, Jeremy S. Collie","doi":"10.1111/fog.12696","DOIUrl":"https://doi.org/10.1111/fog.12696","url":null,"abstract":"Continental shelves experience many human pressures with demersal fisheries central to disturbing the ocean floor. However, ecological processes such as predation rates of benthos and their relationship with bottom fishing are often unknown for large marine ecosystems. We examined the amount of benthos consumed by 14 benthivorous fishes, the overlap between benthos predation and bottom fishing (dredge and trawl gear), and temporal trends in benthivorous fish abundance and the number of fishing trips on the northeast US continental shelf. Mean annual predation (biomass of prey removed) and 95% confidence intervals ranged from .0002 (.0001–.0003) to 3967 (1761–7112) t per 10‐min area squared grid cell and prey taxa for these benthivorous fishes. Predation and bottom fishing had overlapping footprints of activity, which were slightly stronger for dredge gear. Trophic success (ratio of prey biomass eaten to the biomass of the benthivore community per grid cell) revealed more Bivalvia, Gammaridea, and Polychaeta eaten in areas targeted by trawling with more fish biomass. In contrast, dredging did not target fish biomass, but these areas had increased (Echinoidea, Gammaridea, and other benthos) or decreased (Ophiuroidea) trophic success relative to dredging footprint, suggesting habitat preferences for benthic prey and demersal fisheries have converged rather than diverged. Despite declines in bottom fishing, recent increases in benthivorous fish abundance and growing interest in ocean floor use suggest that fisheries managers should ensure benthivores have sufficient prey resources relative to their community size and human pressures to promote long‐term sustainability of demersal fisheries and healthy ecosystems.","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933093","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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