Marcos Arteaga, Sebastián I. Vásquez, Sergio Neira, Luis Cubillos
Recruitment is a critical process in the dynamics of fish populations since it represents the abundance of new fish that enter a population each year. In Ekman-type upwelling ecosystems, wind is a critical factor for small pelagic fish recruitment, as it controls food availability and physical constraints such as turbulence and offshore advection. In this study, we evaluate the effect of wind, chlorophyll-a, and spawning biomass as independent variables on anchovy recruitment. Using generalized additive models (GAMs), we tested (i) the significance of each factor, (ii) the shape of the relationship between recruitment and predictors variables, (iii) recruitment regimes in the series, and (iv) whether extended windy events are associated with low recruitment levels potentially related to offshore transport of early life stages. The study period spanned from 1990 to 2021, focusing on the austral spring in south-central Chile (35–40°S) when both upwelling and anchovy spawning are maximized. GAMs revealed a parabolic relationship between the velocity of upwelling-favorable winds and anchovy recruitment. Maximized recruitment occurred at wind speeds around 6 m s−1 but decreased with winds above 7 m s−1 and below 5 m s−1, and during periods of extended windy events (i.e., those lasting more than 15 days). Chlorophyll-a showed no significance on anchovy recruitment, suggesting that phytoplankton were not a limiting factor for anchovy early survival. We also found that anchovy recruitment regimes were associated with specific wind intensities. We discussed the pertinence of incorporating a recruitment index based on wind in the fishery management of the anchovy in south-central Chile.
{"title":"Effect of wind variability on the recruitment of anchovy Engraulis ringens in the southern Humboldt upwelling ecosystem","authors":"Marcos Arteaga, Sebastián I. Vásquez, Sergio Neira, Luis Cubillos","doi":"10.1111/fog.12677","DOIUrl":"10.1111/fog.12677","url":null,"abstract":"<p>Recruitment is a critical process in the dynamics of fish populations since it represents the abundance of new fish that enter a population each year. In Ekman-type upwelling ecosystems, wind is a critical factor for small pelagic fish recruitment, as it controls food availability and physical constraints such as turbulence and offshore advection. In this study, we evaluate the effect of wind, chlorophyll-a, and spawning biomass as independent variables on anchovy recruitment. Using generalized additive models (GAMs), we tested (i) the significance of each factor, (ii) the shape of the relationship between recruitment and predictors variables, (iii) recruitment regimes in the series, and (iv) whether extended windy events are associated with low recruitment levels potentially related to offshore transport of early life stages. The study period spanned from 1990 to 2021, focusing on the austral spring in south-central Chile (35–40°S) when both upwelling and anchovy spawning are maximized. GAMs revealed a parabolic relationship between the velocity of upwelling-favorable winds and anchovy recruitment. Maximized recruitment occurred at wind speeds around 6 m s<sup>−1</sup> but decreased with winds above 7 m s<sup>−1</sup> and below 5 m s<sup>−1</sup>, and during periods of extended windy events (i.e., those lasting more than 15 days). Chlorophyll-a showed no significance on anchovy recruitment, suggesting that phytoplankton were not a limiting factor for anchovy early survival. We also found that anchovy recruitment regimes were associated with specific wind intensities. We discussed the pertinence of incorporating a recruitment index based on wind in the fishery management of the anchovy in south-central Chile.</p>","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":"33 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141121585","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}
Kaitlyn A. O'Brien, Enric Cortés, William B. Driggers III, Bryan S. Frazier, Robert J. Latour
Understanding spatial ecology and predicting animal movements in response to environmental changes, such as anthropogenic climate change and multidecadal variability, is critical for effective conservation strategies. Niche structuring is key to some coastal shark species and size classes coexisting in the US Atlantic and Gulf of Mexico to limit interspecific and intraspecific interaction. Data from four fishery-independent bottom longline surveys were used to evaluate the abiotic ecological niches of eight species of small and large coastal sharks. Gaussian mixture models separated length composition data into 14 size categories for ecological niche analysis. Generalized additive mixed effect models were fit and coupled with output from dynamic high-resolution ocean models to predict suitable abiotic habitats, evaluate potential shifts in distribution, and explore the impacts of large-scale climatological trends on abiotic habitats from 1994 to 2019. The abiotic niche for small coastal sharks generally tended toward warmer, high salinity, shallow bottom waters close to shore. No overarching niche was found for large coastal sharks, but appreciable ontogenetic differences were seen. Most taxa analyzed exhibited declining annual trends in higher quality habitats, particularly during fall months. The analysis provided evidence of shifts north along the Atlantic, to deeper offshore waters in the Atlantic and Gulf of Mexico, and the potential to redistribute in response to multidecadal climate variability for multiple species. The analytical framework described could aid in developing various spatiotemporal management measures, and results provide insight into the habitat characteristics of several species over broad spatiotemporal ranges and through ontogeny.
{"title":"Niche structure and habitat shifts for coastal sharks of the US Southeast Atlantic and Gulf of Mexico","authors":"Kaitlyn A. O'Brien, Enric Cortés, William B. Driggers III, Bryan S. Frazier, Robert J. Latour","doi":"10.1111/fog.12676","DOIUrl":"10.1111/fog.12676","url":null,"abstract":"<p>Understanding spatial ecology and predicting animal movements in response to environmental changes, such as anthropogenic climate change and multidecadal variability, is critical for effective conservation strategies. Niche structuring is key to some coastal shark species and size classes coexisting in the US Atlantic and Gulf of Mexico to limit interspecific and intraspecific interaction. Data from four fishery-independent bottom longline surveys were used to evaluate the abiotic ecological niches of eight species of small and large coastal sharks. Gaussian mixture models separated length composition data into 14 size categories for ecological niche analysis. Generalized additive mixed effect models were fit and coupled with output from dynamic high-resolution ocean models to predict suitable abiotic habitats, evaluate potential shifts in distribution, and explore the impacts of large-scale climatological trends on abiotic habitats from 1994 to 2019. The abiotic niche for small coastal sharks generally tended toward warmer, high salinity, shallow bottom waters close to shore. No overarching niche was found for large coastal sharks, but appreciable ontogenetic differences were seen. Most taxa analyzed exhibited declining annual trends in higher quality habitats, particularly during fall months. The analysis provided evidence of shifts north along the Atlantic, to deeper offshore waters in the Atlantic and Gulf of Mexico, and the potential to redistribute in response to multidecadal climate variability for multiple species. The analytical framework described could aid in developing various spatiotemporal management measures, and results provide insight into the habitat characteristics of several species over broad spatiotemporal ranges and through ontogeny.</p>","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":"33 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/fog.12676","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141125729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chub mackerel (Scomber japonicus, Scombridae) and blue mackerel (Scomber australasicus) are two important fishery resources in the western North Pacific that spawn eggs during the same season. Although estimating the total egg production (TEP) is important for evaluating the spawning stock biomass of mackerel species, it is difficult to accurately identify formalin-preserved eggs collected during ichthyoplankton surveys. Hence, a new identification criterion that incorporates the effects of water temperature on egg size was developed in this study. The diameter of 37,304 mackerel eggs collected over 16 years (2006–2021) was measured, and frequency distributions of egg size across sea surface temperature (SST) ranges at 1°C interval were constructed. The frequency distributions were classified into two groups using a Gaussian mixture model; based on the results of DNA analysis, the small group was chub mackerel, while the large group was blue mackerel. The SST at the sampling stations and the mean egg size of both groups were negatively correlated. The new identification criterion, incorporating the relationship between SST and egg size, provided reasonable estimates of the TEP of the two mackerel species compared with the conventional criterion. The new species identification approach is applicable to other fish taxa in the western North Pacific.
{"title":"Interspecific and intraspecific difference in egg size of two mackerel (Scomber spp.) species in relation to sea surface temperature in the western North Pacific: A new approach to species identification","authors":"Mikio Watai, Tohya Yasuda, Junji Kinoshita, Mitsuo Nyuji, Satoshi Nagai, Akinori Takasuka, Michio Yoneda","doi":"10.1111/fog.12675","DOIUrl":"10.1111/fog.12675","url":null,"abstract":"<p>Chub mackerel (<i>Scomber japonicus</i>, Scombridae) and blue mackerel (<i>Scomber australasicus</i>) are two important fishery resources in the western North Pacific that spawn eggs during the same season. Although estimating the total egg production (TEP) is important for evaluating the spawning stock biomass of mackerel species, it is difficult to accurately identify formalin-preserved eggs collected during ichthyoplankton surveys. Hence, a new identification criterion that incorporates the effects of water temperature on egg size was developed in this study. The diameter of 37,304 mackerel eggs collected over 16 years (2006–2021) was measured, and frequency distributions of egg size across sea surface temperature (SST) ranges at 1°C interval were constructed. The frequency distributions were classified into two groups using a Gaussian mixture model; based on the results of DNA analysis, the small group was chub mackerel, while the large group was blue mackerel. The SST at the sampling stations and the mean egg size of both groups were negatively correlated. The new identification criterion, incorporating the relationship between SST and egg size, provided reasonable estimates of the TEP of the two mackerel species compared with the conventional criterion. The new species identification approach is applicable to other fish taxa in the western North Pacific.</p>","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":"33 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140934838","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}
Rui Wang, Shigang Liu, Ran Zhang, Hai Li, Puqing Song, Yuan Li, Longshan Lin
Antarctic krill Euphausia superba is a key species in the Southern Ocean ecosystem and has important ecological value. It is also one of the main fishery resources in the Southern Ocean with high economic value. In recent years, with the development of krill fishery and rapid climate change, the conservation and management of krill resources have faced unprecedented challenges. The krill resource is different from the general fishery resources. Due to the krill schooling characteristics, fishery data has some advantages over scientific survey data. Reviewing and analyzing the krill fishery data is necessary. Therefore, in this study, four fishery resource indices (FRIs) were calculated based on Antarctic krill fishery data, and based on the environmental dependence of Antarctic krill, the FRI with the strongest environmental dependence was screened by using the Gradient Forest Model, and the step changes of the FRI with strongest environmental dependence was examined by using the sequential t-test analyses of regime shifts (STARS). The generalized additive model (GAM) to analyze the correlation between the FRI with the strongest environmental dependence and the main environmental factors, and then explore the resource status of Antarctic krill in the study area. The model results showed that the “FRI_hual” had the strongest environmental dependence and was a better indicator of the status of the Antarctic krill in the study area than the others. In the 2009–2010 year, “FRI_hual” had an obvious regime shift. The interaction of environmental factors “ice_area_2” and “SSH_1” has a great impact on “FRI_hual”. Methods used and results obtained in the study can provide new ideas and a scientific reference for future work, including integrated stock assessment of krill and krill resource monitoring, conservation, and management based on the ecosystem.
{"title":"Analyzing fishery data and exploring the resource status of Antarctic krill based on its environmental dependence","authors":"Rui Wang, Shigang Liu, Ran Zhang, Hai Li, Puqing Song, Yuan Li, Longshan Lin","doi":"10.1111/fog.12674","DOIUrl":"10.1111/fog.12674","url":null,"abstract":"<p>Antarctic krill <i>Euphausia superba</i> is a key species in the Southern Ocean ecosystem and has important ecological value. It is also one of the main fishery resources in the Southern Ocean with high economic value. In recent years, with the development of krill fishery and rapid climate change, the conservation and management of krill resources have faced unprecedented challenges. The krill resource is different from the general fishery resources. Due to the krill schooling characteristics, fishery data has some advantages over scientific survey data. Reviewing and analyzing the krill fishery data is necessary. Therefore, in this study, four fishery resource indices (FRIs) were calculated based on Antarctic krill fishery data, and based on the environmental dependence of Antarctic krill, the FRI with the strongest environmental dependence was screened by using the Gradient Forest Model, and the step changes of the FRI with strongest environmental dependence was examined by using the sequential t-test analyses of regime shifts (STARS). The generalized additive model (GAM) to analyze the correlation between the FRI with the strongest environmental dependence and the main environmental factors, and then explore the resource status of Antarctic krill in the study area. The model results showed that the “FRI_hual” had the strongest environmental dependence and was a better indicator of the status of the Antarctic krill in the study area than the others. In the 2009–2010 year, “FRI_hual” had an obvious regime shift. The interaction of environmental factors “ice_area_2” and “SSH_1” has a great impact on “FRI_hual”. Methods used and results obtained in the study can provide new ideas and a scientific reference for future work, including integrated stock assessment of krill and krill resource monitoring, conservation, and management based on the ecosystem.</p>","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":"33 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140367992","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}
Mitsuhide Sato, Takaki Tsubono, Jun Yamaguchi, Shigenobu Takeda
To test the potential of high-resolution satellite image analysis for assessing and predicting the mesoscale (<10 km in this study) effects of climate and environmental change on temperature and primary productivity in fishing grounds, we conducted satellite image analysis around an island in a coastal strait west of Japan from 2018 to 2023. We observed a distinct north–south gradient in sea surface temperature (SST) and chlorophyll a concentration (CHL) over approximately 20 km of the transect, which was likely affected by the current system. The model configuration suggests that the frequency of southward currents during winter–spring can control the magnitude of spring phytoplankton blooms. In the study region, an increase in SST at a rate of 0.06–0.13°C y−1 occurred during the study period, accompanied by a decrease in CHL. The north–south gradient in the rate of change suggests that the variation in the temperature and flow rate of the Kuroshio Current into the study area was due to these abrupt changes. The relationship between the annual mean SST and CHL was also spatially heterogeneous, showing a higher sensitivity of CHL to SST in the southwest of the island than in the north. In addition to the intrusion of warm and oligotrophic Kuroshio waters, the spread of less saline and more eutrophic coastal waters likely influenced this spatial heterogeneity. The satellite image analysis in the present study successfully revealed mesoscale mosaics of environmental conditions in coastal fishery grounds.
{"title":"Mesoscale mosaics of interannual variations in surface temperature, chlorophyll a concentration, and their relation in a coastal fishing ground","authors":"Mitsuhide Sato, Takaki Tsubono, Jun Yamaguchi, Shigenobu Takeda","doi":"10.1111/fog.12673","DOIUrl":"10.1111/fog.12673","url":null,"abstract":"<p>To test the potential of high-resolution satellite image analysis for assessing and predicting the mesoscale (<10 km in this study) effects of climate and environmental change on temperature and primary productivity in fishing grounds, we conducted satellite image analysis around an island in a coastal strait west of Japan from 2018 to 2023. We observed a distinct north–south gradient in sea surface temperature (SST) and chlorophyll <i>a</i> concentration (CHL) over approximately 20 km of the transect, which was likely affected by the current system. The model configuration suggests that the frequency of southward currents during winter–spring can control the magnitude of spring phytoplankton blooms. In the study region, an increase in SST at a rate of 0.06–0.13°C y<sup>−1</sup> occurred during the study period, accompanied by a decrease in CHL. The north–south gradient in the rate of change suggests that the variation in the temperature and flow rate of the Kuroshio Current into the study area was due to these abrupt changes. The relationship between the annual mean SST and CHL was also spatially heterogeneous, showing a higher sensitivity of CHL to SST in the southwest of the island than in the north. In addition to the intrusion of warm and oligotrophic Kuroshio waters, the spread of less saline and more eutrophic coastal waters likely influenced this spatial heterogeneity. The satellite image analysis in the present study successfully revealed mesoscale mosaics of environmental conditions in coastal fishery grounds.</p>","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":"33 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140147437","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}
Elier Armas, Hugo Arancibia, Sergio Neira, María Carla Marín
Engraulis ringens (anchovy) is a small pelagic fish of the Family Engraulidae that inhabits the neretic-coastal zone from northern Peru to south-central Chile. It is the main resource species of industrial fishing of northern Chile, representing 80% of the annual landings of the purse seine fleet. The history of this fishery (1985–2023) shows a strong decrease in annual industrial landings, especially during extreme El Niño–Southern Oscillation (ENSO) events. The greatest decrease in landings in two decades occurred in 2020, coinciding with a cold La Niña event, which had not been observed in previous La Niña events. We evaluated whether the current decrease in annual landings of E. ringens is associated with oceanographic changes in northern Chile during El Niño or La Niña events. We applied a neuronal network model to identify the spatial and temporal distribution of E. ringens using the catch probability of each boat of the industrial purse seine fleet. The selected oceanographic variables (sea surface temperature, salinity, depth of the mixed layer, sea height and currents) for the 2003–2020 period were obtained from the Copernicus Marine Environment Monitoring Service (CMEMS program) and used as predictor variables of the monthly landings of E. ringens. The neural network model explained 97% of the monthly variability of catch probability of E. ringens by the industrial purse seine fleet. The spatial distribution of catch probability of E. ringens was analyzed independently for El Niño (2015), La Niña (2007, 2013, and 2020), and Neutral (2004) years. We found that catch probability extended further west during La Niña events (except for 2020), occupying a greater area, but were limited to a 10 nautical mile coastal strip during the El Niño event. The spatial distribution of catch probability in the Neutral condition was near the coast, although not as restricted as during the El Niño event. The higher catch probabilities in the La Niña event of 2020 were near the coast, in contrast to the previous La Niña events of 2007 and 2013, due to the restriction of the optimal habitat of E. ringens in response to changes in oceanographic conditions. The application of the results of this study will allow understanding and probably anticipating the consequences that extreme ENSO events could have on the catch probability of the industrial anchovy purse seine fleet in northern Chile.
Engraulis ringens(凤尾鱼)是一种小型中上层鱼类,属于 Engraulidae 科,栖息于秘鲁北部至智利中南部的近海沿海地区。它是智利北部工业化捕捞的主要资源品种,占围网船队年上岸量的 80%。该渔业的历史(1985-2023 年)显示,年工业上岸量大幅下降,尤其是在厄尔尼诺-南方涛动(ENSO)极端事件期间。2020 年上岸量出现了 20 年来的最大降幅,当时正值寒冷的拉尼娜事件,而在之前的拉尼娜事件中并未观察到这一现象。我们评估了目前每年 E. ringens 上岸量的减少是否与厄尔尼诺或拉尼娜事件期间智利北部海洋变化有关。我们采用神经元网络模型,利用工业围网船队每艘船的捕获概率来确定 E. ringens 的时空分布。我们从哥白尼海洋环境监测服务(CMEMS 计划)中获取了 2003-2020 年期间选定的海洋变量(海面温度、盐度、混合层深度、海平面高度和海流),并将其用作 E. ringens 月上岸量的预测变量。神经网络模型解释了工业围网船队捕获 E. ringens 的月度变化概率的 97%。对厄尔尼诺年(2015 年)、拉尼娜年(2007 年、2013 年和 2020 年)和中性年(2004 年)E. ringens 捕获概率的空间分布进行了独立分析。我们发现,在拉尼娜事件期间(2020 年除外),捕获概率进一步向西扩展,占据了更大的区域,但在厄尔尼诺事件期间,捕获概率仅限于 10 海里的沿海地带。在中性条件下,捕获概率的空间分布靠近海岸,但不像厄尔尼诺事件期间那样受到限制。与 2007 年和 2013 年的拉尼娜事件不同,2020 年的拉尼娜事件中较高的捕获概率出现在海岸附近,这是因为 E. ringens 的最佳栖息地因海洋条件的变化而受到限制。应用该研究结果将有助于了解并预测极端厄尔尼诺/南方涛动事件可能对智利北部工业化围网捕捞凤尾鱼船队的捕获概率造成的后果。
{"title":"Neural network approach for detecting spatial changes in catch probability of Engraulis ringens during El Niño-Southern Oscillation events in northern Chile","authors":"Elier Armas, Hugo Arancibia, Sergio Neira, María Carla Marín","doi":"10.1111/fog.12672","DOIUrl":"10.1111/fog.12672","url":null,"abstract":"<p><i>Engraulis ringens</i> (anchovy) is a small pelagic fish of the Family Engraulidae that inhabits the neretic-coastal zone from northern Peru to south-central Chile. It is the main resource species of industrial fishing of northern Chile, representing 80% of the annual landings of the purse seine fleet. The history of this fishery (1985–2023) shows a strong decrease in annual industrial landings, especially during extreme El Niño–Southern Oscillation (ENSO) events. The greatest decrease in landings in two decades occurred in 2020, coinciding with a cold La Niña event, which had not been observed in previous La Niña events. We evaluated whether the current decrease in annual landings of <i>E. ringens</i> is associated with oceanographic changes in northern Chile during El Niño or La Niña events. We applied a neuronal network model to identify the spatial and temporal distribution of <i>E. ringens</i> using the catch probability of each boat of the industrial purse seine fleet. The selected oceanographic variables (sea surface temperature, salinity, depth of the mixed layer, sea height and currents) for the 2003–2020 period were obtained from the Copernicus Marine Environment Monitoring Service (CMEMS program) and used as predictor variables of the monthly landings of <i>E. ringens</i>. The neural network model explained 97% of the monthly variability of catch probability of <i>E. ringens</i> by the industrial purse seine fleet. The spatial distribution of catch probability of <i>E. ringens</i> was analyzed independently for El Niño (2015), La Niña (2007, 2013, and 2020), and Neutral (2004) years. We found that catch probability extended further west during La Niña events (except for 2020), occupying a greater area, but were limited to a 10 nautical mile coastal strip during the El Niño event. The spatial distribution of catch probability in the Neutral condition was near the coast, although not as restricted as during the El Niño event. The higher catch probabilities in the La Niña event of 2020 were near the coast, in contrast to the previous La Niña events of 2007 and 2013, due to the restriction of the optimal habitat of <i>E. ringens</i> in response to changes in oceanographic conditions. The application of the results of this study will allow understanding and probably anticipating the consequences that extreme ENSO events could have on the catch probability of the industrial anchovy purse seine fleet in northern Chile.</p>","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":"33 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140025916","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}
The lunar phase is known to influence the spawning activity of some Lutjanus snappers, however, information on its influence on feeding activity is limited. In the present study, diet, feeding habit, and lunar periodicity of feeding activity on two reef-associated sympatric snappers, blackspot snapper Lutjanus fulviflamma (n = 339) and blacktail snapper L. fulvus (n = 172), were investigated by stomach content analyses in the Yaeyama region (24°N, 124°E), southern Japan. Diets of the two snappers were similar and mainly consumed fishes, crabs, and shrimps. Relative volume of the stomach contents to body weight was compared by season, lunar day, and predator size using a generalized linear model. Larger individuals fed on larger fish prey and tended to show higher stomach fullness for both snappers. Periodic regression revealed that the lunar periodicity of the feeding activity is different between the two Lutjanus snappers. The feeding activity of L. fulviflamma increased around the spring tides of both new and full moons during a single lunar cycle. On the other hand, the feeding activity of L. fulvus increased only before the new moon but decreased before the full moon. Spawning of L. fulvus is known to occur only around the full moon, and enlarged gonads are considered to suppress the feeding activity of the species. Individuals with much stomach contents did not have large gonads for both snappers, and this supports the above supposition. Spawning and feeding activities are closely linked and simultaneous temporal analysis will enable a clearer understanding of the ecological role of these predators.
{"title":"Feeding ecology of two reef-associated snappers (Lutjanus fulviflamma and L. fulvus): Influence of lunar phase on feeding activity","authors":"Tamaki Shimose","doi":"10.1111/fog.12670","DOIUrl":"10.1111/fog.12670","url":null,"abstract":"<p>The lunar phase is known to influence the spawning activity of some <i>Lutjanus</i> snappers, however, information on its influence on feeding activity is limited. In the present study, diet, feeding habit, and lunar periodicity of feeding activity on two reef-associated sympatric snappers, blackspot snapper <i>Lutjanus fulviflamma</i> (n = 339) and blacktail snapper <i>L. fulvus</i> (n = 172), were investigated by stomach content analyses in the Yaeyama region (24°N, 124°E), southern Japan. Diets of the two snappers were similar and mainly consumed fishes, crabs, and shrimps. Relative volume of the stomach contents to body weight was compared by season, lunar day, and predator size using a generalized linear model. Larger individuals fed on larger fish prey and tended to show higher stomach fullness for both snappers. Periodic regression revealed that the lunar periodicity of the feeding activity is different between the two <i>Lutjanus</i> snappers. The feeding activity of <i>L. fulviflamma</i> increased around the spring tides of both new and full moons during a single lunar cycle. On the other hand, the feeding activity of <i>L. fulvus</i> increased only before the new moon but decreased before the full moon. Spawning of <i>L. fulvus</i> is known to occur only around the full moon, and enlarged gonads are considered to suppress the feeding activity of the species. Individuals with much stomach contents did not have large gonads for both snappers, and this supports the above supposition. Spawning and feeding activities are closely linked and simultaneous temporal analysis will enable a clearer understanding of the ecological role of these predators.</p>","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":"33 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139948400","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}
Shingo Kimura, Sachie Miyazaki, Hiroaki Onda, Takashi Kitagawa, Yoichi Miyake, Michael J. Miller, Katsumi Tsukamoto
To understand the larval distribution, size variation, and stable isotope ratios of Japanese eel leptocephali in relation to the salinity front and their feeding ecology, larvae from 7 research cruises (2002–2013) in the North Equatorial Current (NEC) spawning area were examined. The smallest early-stage larvae were distributed south of or near the salinity front, confirming that the salinity front is an important oceanic feature to understand spawning locations of the Japanese eel. Larger size larvae tended to distribute into higher latitudes. Transport to northern latitudes with their growth would facilitate transport into the Kuroshio region, but retention in the Subtropical Countercurrent (STCC) might be detrimental. Preleptocephalus isotope ratios reflected maternal ratios, but feeding-stage leptocephali (8–56 mm) tended to have higher ∂15N values at lower latitudes typically in areas south of a salinity front. Feeding larvae quickly assimilate isotope ratios from the NEC after spawning and early growth. Large differences of ∂13C values of larvae between the NEC and STCC might vary with spatial baselines in the two currents. However, diel vertical migrations should be considered, because the isotope ratios in particulate organic matter distinctly depend on the depth. Comparisons among Japanese eel larvae and other taxa of leptocephali in the NEC illustrate the need for further studies on the trophic ecology of leptocephali.
{"title":"Distribution and stable isotope ratio characteristics of Japanese eel leptocephali in relation to hydrographic structure of their Pacific Ocean spawning area","authors":"Shingo Kimura, Sachie Miyazaki, Hiroaki Onda, Takashi Kitagawa, Yoichi Miyake, Michael J. Miller, Katsumi Tsukamoto","doi":"10.1111/fog.12671","DOIUrl":"10.1111/fog.12671","url":null,"abstract":"<p>To understand the larval distribution, size variation, and stable isotope ratios of Japanese eel leptocephali in relation to the salinity front and their feeding ecology, larvae from 7 research cruises (2002–2013) in the North Equatorial Current (NEC) spawning area were examined. The smallest early-stage larvae were distributed south of or near the salinity front, confirming that the salinity front is an important oceanic feature to understand spawning locations of the Japanese eel. Larger size larvae tended to distribute into higher latitudes. Transport to northern latitudes with their growth would facilitate transport into the Kuroshio region, but retention in the Subtropical Countercurrent (STCC) might be detrimental. Preleptocephalus isotope ratios reflected maternal ratios, but feeding-stage leptocephali (8–56 mm) tended to have higher ∂<sup>15</sup>N values at lower latitudes typically in areas south of a salinity front. Feeding larvae quickly assimilate isotope ratios from the NEC after spawning and early growth. Large differences of ∂<sup>13</sup>C values of larvae between the NEC and STCC might vary with spatial baselines in the two currents. However, diel vertical migrations should be considered, because the isotope ratios in particulate organic matter distinctly depend on the depth. Comparisons among Japanese eel larvae and other taxa of leptocephali in the NEC illustrate the need for further studies on the trophic ecology of leptocephali.</p>","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":"33 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/fog.12671","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139948193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jessica A. Bolin, Karen Evans, David S. Schoeman, Claire M. Spillman, Thomas S. Moore II, Jason R. Hartog, Scott F. Cummins, Kylie L. Scales
Meat quality is of paramount importance in the fisheries and aquaculture industries, but the quality of seafood can be affected by environmental variability and change, creating uncertainties in the delivery of consistent, high-end product. Reports from fishers operating in an Australian fishery catching broadbill swordfish (Xiphias gladius) suggest that anomalously warm waters are linked with myoliquefaction of muscle tissue. The condition affects the marketability of fish by turning the meat into a soft, mushy texture post-mortem and is caused by infection by the myxozoan parasite Kudoa musculoliquefaciens. Here, we combine microscopy, molecular techniques and ecological modelling to explore potential environmental drivers of the prevalence and intensity of K. musculoliquefaciens in swordfish, as a first step in understanding how a warming ocean might exacerbate the risk of harvesting an infected swordfish and the resultant potential risk of myoliquefaction. We develop predictive dynamic risk surfaces on seasonal timescales, with results revealing both the likelihood of harvesting an infected swordfish and the intensity of parasite load increase during the Austral summer. The prevalence of the parasite further increases in the region dominated by the East Australian Current, when locally warm areas are atypically cool and when average monthly temperatures are more variable. These findings provide information useful in predicting the conditions under which the risk of harvesting infected swordfish might be intensified, enabling adaptation to climate change impacts and optimisation of decision-making when fishing under risky conditions.
肉质对渔业和水产养殖业至关重要,但海产品的质量可能会受到环境变化的影响,从而给提供稳定的高端产品带来不确定性。在澳大利亚捕捞宽吻剑鱼(Xiphias gladius)的渔民的报告表明,异常温暖的水域与肌肉组织的肌溶解有关。这种情况会使鱼死后肉质变软,影响鱼的销路,是由肌寄生虫 Kudoa musculoliquefaciens 感染引起的。在这里,我们将显微镜、分子技术和生态建模结合起来,探索箭鱼中 K. musculoliquefaciens 感染率和强度的潜在环境驱动因素,以此作为了解海洋变暖如何加剧捕捞受感染箭鱼的风险以及由此产生的肌溶解潜在风险的第一步。我们开发了以季节为时间尺度的预测性动态风险曲面,结果显示,在澳大拉西亚夏季,捕获受感染箭鱼的可能性和寄生虫负荷的强度都会增加。在东澳大利亚洋流主导的区域,寄生虫的流行率进一步上升,此时局部温暖地区异常凉爽,月平均气温变化较大。这些发现提供了有用的信息,有助于预测在何种条件下捕捞受感染箭鱼的风险可能会增加,从而适应气候变化的影响,并优化在风险条件下捕捞时的决策。
{"title":"A warming western boundary current increases the prevalence of commercially disruptive parasites in broadbill swordfish","authors":"Jessica A. Bolin, Karen Evans, David S. Schoeman, Claire M. Spillman, Thomas S. Moore II, Jason R. Hartog, Scott F. Cummins, Kylie L. Scales","doi":"10.1111/fog.12669","DOIUrl":"10.1111/fog.12669","url":null,"abstract":"<p>Meat quality is of paramount importance in the fisheries and aquaculture industries, but the quality of seafood can be affected by environmental variability and change, creating uncertainties in the delivery of consistent, high-end product. Reports from fishers operating in an Australian fishery catching broadbill swordfish (<i>Xiphias gladius</i>) suggest that anomalously warm waters are linked with myoliquefaction of muscle tissue. The condition affects the marketability of fish by turning the meat into a soft, mushy texture post-mortem and is caused by infection by the myxozoan parasite <i>Kudoa musculoliquefaciens</i>. Here, we combine microscopy, molecular techniques and ecological modelling to explore potential environmental drivers of the prevalence and intensity of <i>K. musculoliquefaciens</i> in swordfish, as a first step in understanding how a warming ocean might exacerbate the risk of harvesting an infected swordfish and the resultant potential risk of myoliquefaction. We develop predictive dynamic risk surfaces on seasonal timescales, with results revealing both the likelihood of harvesting an infected swordfish and the intensity of parasite load increase during the Austral summer. The prevalence of the parasite further increases in the region dominated by the East Australian Current, when locally warm areas are atypically cool and when average monthly temperatures are more variable. These findings provide information useful in predicting the conditions under which the risk of harvesting infected swordfish might be intensified, enabling adaptation to climate change impacts and optimisation of decision-making when fishing under risky conditions.</p>","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":"33 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/fog.12669","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139751024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anna Karolina Oliveira de Queiroz, Maria A. Gasalla, Marcele Laux, Renato Renison Moreira Oliveira, Fabricio dos Anjos Santa Rosa, Audun Schrøder-Nielsen, Felippe A. Postuma, João Bráullio de Luna Sales, Hugo J. de Boer, Quentin Mauvisseau, Jonathan Stuart Ready
Clupeiform fishes are ecologically and economically important species contributing to industrial and artisanal fisheries worldwide. They represent key links in food webs, influencing the dynamic between trophic levels. The dietary interactions of these species are poorly studied in many regions, yet essential for fisheries management. To elucidate the role of these species in food webs of the Southern Brazilian Bight pelagic fisheries, we used metabarcoding analysis of fish stomach contents of Clupeiformes and possible predators. Onboard sampling from March to September 2016 allowed for processing of 87 stomach samples representing 31 species (including 12 samples representing three species of Clupeiformes). Links between trophic levels showed the predominance of Sardinella brasiliensis and Engraulis anchoita as important dietary items of a large range of fishes (28 species belonging to 18 families) and representing the majority of the total prey read abundance assigned to clupeiform fishes (~46% and ~32%, respectively). Opisthonema oglinum contributed to the diet of 16 species in 13 families and ~18% of total read abundance of clupeiform fishes as prey. The appearance of multiple clupeiform taxa in the diet of predators that are not commonly associated with pelagic prey indicates that ecosystem-based fisheries management should not be separated between pelagic and demersal fisheries. The diet of Clupeiformes revealed an unexpectedly large diversity of fish species and a low proportion of invertebrates (<5% of clupeiform prey reads). This was likely due to a combination of both a limitation of the metabarcoding method (primer bias and low success of invertebrate taxonomic identification) as well as a contribution of early life stages (ichthyoplankton) to the diet of these fishes. The potential role of clupeiform fish populations as a constraint to the recruitment from the ichthyoplanktonic phase of other ecologically or commercially important fishes should be considered as an important direction for future studies.
{"title":"Dietary metabarcoding of keystone sardine species reveals the importance of their ichthyoplankton prey in food webs of the Southern Brazilian Bight fisheries","authors":"Anna Karolina Oliveira de Queiroz, Maria A. Gasalla, Marcele Laux, Renato Renison Moreira Oliveira, Fabricio dos Anjos Santa Rosa, Audun Schrøder-Nielsen, Felippe A. Postuma, João Bráullio de Luna Sales, Hugo J. de Boer, Quentin Mauvisseau, Jonathan Stuart Ready","doi":"10.1111/fog.12668","DOIUrl":"10.1111/fog.12668","url":null,"abstract":"<p>Clupeiform fishes are ecologically and economically important species contributing to industrial and artisanal fisheries worldwide. They represent key links in food webs, influencing the dynamic between trophic levels. The dietary interactions of these species are poorly studied in many regions, yet essential for fisheries management. To elucidate the role of these species in food webs of the Southern Brazilian Bight pelagic fisheries, we used metabarcoding analysis of fish stomach contents of Clupeiformes and possible predators. Onboard sampling from March to September 2016 allowed for processing of 87 stomach samples representing 31 species (including 12 samples representing three species of Clupeiformes). Links between trophic levels showed the predominance of <i>Sardinella brasiliensis</i> and <i>Engraulis anchoita</i> as important dietary items of a large range of fishes (28 species belonging to 18 families) and representing the majority of the total prey read abundance assigned to clupeiform fishes (~46% and ~32%, respectively). <i>Opisthonema oglinum</i> contributed to the diet of 16 species in 13 families and ~18% of total read abundance of clupeiform fishes as prey. The appearance of multiple clupeiform taxa in the diet of predators that are not commonly associated with pelagic prey indicates that ecosystem-based fisheries management should not be separated between pelagic and demersal fisheries. The diet of Clupeiformes revealed an unexpectedly large diversity of fish species and a low proportion of invertebrates (<5% of clupeiform prey reads). This was likely due to a combination of both a limitation of the metabarcoding method (primer bias and low success of invertebrate taxonomic identification) as well as a contribution of early life stages (ichthyoplankton) to the diet of these fishes. The potential role of clupeiform fish populations as a constraint to the recruitment from the ichthyoplanktonic phase of other ecologically or commercially important fishes should be considered as an important direction for future studies.</p>","PeriodicalId":51054,"journal":{"name":"Fisheries Oceanography","volume":"33 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/fog.12668","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139751035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}