Pub Date : 2024-11-02DOI: 10.1016/j.fishres.2024.107213
Amini I. Hamad , Christopher A. Muhando , Batuli M. Yahya
Octopus cyanea (Gray, 1849) is a benthic and diurnally active species found in tropical and subtropical reefs. It is harvested for commercial and subsistence purposes, but some factors in Zanzibar challenge its catch. This study was conducted to determine variations in O. cyanea catch between on-foot and dive fishing methods in Zanzibar. Information from this study would help in the establishment of management plans, which are still challenging in Zanzibar. The catch size, catch rate, and individual size of octopuses from dive and on-foot fishing were determined. Results revealed that about 54.11 % of all octopuses were caught by on-foot fishing and 45.89 % by dive fishing. However, the average catch size (by weight and length) was lower for on-foot fishing than for dive fishing. Moreover, the catch size and catch rate per fisher were higher for dive fishers than for on-foot fishers. The proportion of octopuses weighing ≥ 1000 g constitutes 49 % and 26 % of the total catch by dive and on-foot fishing, respectively, indicating that dive fishing captures a significantly higher percentage of larger individuals than on-foot fishing. Therefore, the concentrated on-foot fishing in shallow water could affect more recruits and juveniles, while high fishing efforts in deep water by dive fishers could impact more spawners and brooders found in these areas. Given these observations, this study emphasizes the necessity of conducting long-term research to accurately identify the peak breeding, spawning, and recruitment seasons.
章鱼青（Gray，1849 年）是热带和亚热带珊瑚礁中的一种底栖昼伏夜出的物种。它被捕捞用于商业和生计目的，但桑给巴尔的一些因素对其捕获量构成了挑战。本研究旨在确定桑给巴尔徒步捕捞和潜水捕捞两种捕捞方式下 O. cyanea 捕获量的变化。这项研究的信息将有助于制定管理计划，而这在桑给巴尔仍是一项挑战。研究测定了潜水和徒步捕捞章鱼的捕获量、捕获率和个体大小。结果显示，约 54.11 % 的章鱼是通过徒步捕捞捕获的，45.89 % 是通过潜水捕捞捕获的。然而，徒步捕捞的平均捕获量（按重量和长度计算）低于潜水捕捞。此外，潜水捕鱼者的渔获量和人均渔获率均高于徒步捕鱼者。体重≥1000克的章鱼在潜捕和徒步捕捞总渔获量中所占比例分别为49%和26%，表明潜捕捕获的较大个体比例明显高于徒步捕捞。因此，集中在浅水区的徒步捕捞可能会影响到更多的新鱼和幼鱼，而潜水捕捞者在深水区的高捕捞强度可能会影响到在这些区域发现的更多产卵者和育雏者。鉴于这些观察结果，本研究强调了进行长期研究的必要性，以准确确定繁殖、产卵和新陈代谢的高峰季节。
{"title":"The influence of fishing methods on catch size, catch rate, and size distribution of Octopus cyanea (Gray, 1849) in Zanzibar, Tanzania","authors":"Amini I. Hamad , Christopher A. Muhando , Batuli M. Yahya","doi":"10.1016/j.fishres.2024.107213","DOIUrl":"10.1016/j.fishres.2024.107213","url":null,"abstract":"<div><div><em>Octopus cyanea</em> (Gray, 1849) is a benthic and diurnally active species found in tropical and subtropical reefs. It is harvested for commercial and subsistence purposes, but some factors in Zanzibar challenge its catch. This study was conducted to determine variations in <em>O. cyanea</em> catch between on-foot and dive fishing methods in Zanzibar. Information from this study would help in the establishment of management plans, which are still challenging in Zanzibar. The catch size, catch rate, and individual size of octopuses from dive and on-foot fishing were determined. Results revealed that about 54.11 % of all octopuses were caught by on-foot fishing and 45.89 % by dive fishing. However, the average catch size (by weight and length) was lower for on-foot fishing than for dive fishing. Moreover, the catch size and catch rate per fisher were higher for dive fishers than for on-foot fishers. The proportion of octopuses weighing ≥ 1000 g constitutes 49 % and 26 % of the total catch by dive and on-foot fishing, respectively, indicating that dive fishing captures a significantly higher percentage of larger individuals than on-foot fishing. Therefore, the concentrated on-foot fishing in shallow water could affect more recruits and juveniles, while high fishing efforts in deep water by dive fishers could impact more spawners and brooders found in these areas. Given these observations, this study emphasizes the necessity of conducting long-term research to accurately identify the peak breeding, spawning, and recruitment seasons.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"281 ","pages":"Article 107213"},"PeriodicalIF":2.2,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572800","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}
In recent years, with the decline in marine fishery resources, ecosystem-based fisheries management (EBFM) has emerged as an important paradigm in fisheries management, emphasizing the need for species distribution information. Selecting appropriate habitat models is crucial in species distribution studies. Bayesian models could reduce the reliance of species distribution on the data and are particularly suitable for small datasets in marine surveys. In this study, we constructed three Bayesian models to analyze the spatial distribution and shared suitable habitats of four Gobiidae (Myersina filifer, Chaemrichthys stigmatias, Amblychaeturichthys hexanema, and Amoya pflaumi) in Haizhou Bay, China. The interspecific associations of these species were also evaluated using Pearson correlation coefficient (r). Our analyses found that Bayesian regularized neural network (BRNN) model performed better than the other two Bayesian models, and the four Gobiidae species mainly coexisted in the central and southern coastal areas of Haizhou Bay, prey, sea bottom temperature and sediment were the main correlated factors on the habitat of Gobiidae. Furthermore, although the four species exhibited similar feeding habits, intense interspecific competition might not occur due to their considerable dietary breadth, with species associations reflecting the similarity of habitat preferences. For example, M. filifer and A. hexanema inhabited similar areas in spring, and their species association was also relatively high (0.64). This study will help to enhance our understanding of the habitat preferences and interspecific associations of Gobiidae, and provide a framework of spatial based fisheries management at multispecies level in marine bay ecosystems.
近年来，随着海洋渔业资源的减少，基于生态系统的渔业管理（EBFM）已成为渔业管理的一个重要范式，强调了对物种分布信息的需求。在物种分布研究中，选择合适的生境模型至关重要。贝叶斯模型可以减少物种分布对数据的依赖，尤其适合海洋调查中的小数据集。在本研究中，我们构建了三个贝叶斯模型来分析中国海州湾四种戈壁鱼科（Myersina filifer、Chaemrichthys stigmatias、Amblychaeturichthys hexanema和Amoya pflaumi）的空间分布和共享适宜生境。我们还利用皮尔逊相关系数（r）评估了这些物种的种间联系。分析发现，贝叶斯正则化神经网络（BRNN）模型的表现优于其他两种贝叶斯模型，戈壁鱼的四个物种主要共存于海州湾中部和南部沿海地区，猎物、海底温度和沉积物是戈壁鱼栖息地的主要相关因子。此外，虽然四种戈壁鱼的摄食习性相似，但由于它们的食性相当广泛，种间竞争可能并不激烈，物种间的关联反映了对生境偏好的相似性。例如，M. filifer 和 A. hexanema 在春季栖息在相似的区域，它们的物种关联度也相对较高（0.64）。这项研究将有助于加深我们对戈壁鱼科栖息地偏好和种间关联的了解，并为海湾生态系统多物种水平的空间渔业管理提供框架。
{"title":"Bayesian modeling-based analysis on the shared habitat and species association between four Gobiidae in a marine bay ecosystem","authors":"Duqing Shen , Jie Yin , Yunlei Zhang , Chongliang Zhang , Binduo Xu , Yupeng Ji , Yiping Ren , Ying Xue","doi":"10.1016/j.fishres.2024.107212","DOIUrl":"10.1016/j.fishres.2024.107212","url":null,"abstract":"<div><div>In recent years, with the decline in marine fishery resources, ecosystem-based fisheries management (EBFM) has emerged as an important paradigm in fisheries management, emphasizing the need for species distribution information. Selecting appropriate habitat models is crucial in species distribution studies. Bayesian models could reduce the reliance of species distribution on the data and are particularly suitable for small datasets in marine surveys. In this study, we constructed three Bayesian models to analyze the spatial distribution and shared suitable habitats of four Gobiidae (<em>Myersina filifer</em>, <em>Chaemrichthys stigmatias</em>, <em>Amblychaeturichthys hexanema</em>, and <em>Amoya pflaumi</em>) in Haizhou Bay, China. The interspecific associations of these species were also evaluated using Pearson correlation coefficient (r). Our analyses found that Bayesian regularized neural network (BRNN) model performed better than the other two Bayesian models, and the four Gobiidae species mainly coexisted in the central and southern coastal areas of Haizhou Bay, prey, sea bottom temperature and sediment were the main correlated factors on the habitat of Gobiidae. Furthermore, although the four species exhibited similar feeding habits, intense interspecific competition might not occur due to their considerable dietary breadth, with species associations reflecting the similarity of habitat preferences. For example, <em>M. filifer</em> and <em>A. hexanema</em> inhabited similar areas in spring, and their species association was also relatively high (0.64). This study will help to enhance our understanding of the habitat preferences and interspecific associations of Gobiidae, and provide a framework of spatial based fisheries management at multispecies level in marine bay ecosystems.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"281 ","pages":"Article 107212"},"PeriodicalIF":2.2,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572889","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}
Pub Date : 2024-11-02DOI: 10.1016/j.fishres.2024.107216
Sukree Hajisamae , Kay Khine Soe , Sofiyudin Maae , Saweit Chaymongkol , Akbar John
This study presents the first comprehensive assessment of the population structure and feeding habits of Carcinoscorpius rotundicauda in Thailand. Sample collection was conducted using crab gill nets at seven sampling sites characterized by distinct ecosystem attributes in Pattani Bay between February 2019 and March 2020. Our findings indicate the presence of a single Asian horseshoe crab (HSC) species within the bay, with a sex ratio of approximately 1:1 (48.1 % males, 51.9 % females) that did not deviate significantly from parity. Habitat variation within the bay did not influence HSC abundance (P > 0.05) whereas monthly abundance fluctuations were highly significant (P < 0.001), peaking in March and reaching the lowest in September. Positive correlations were observed between HSC abundance and environmental factors including dissolved oxygen, temperature, water pH, water depth, and chlorophyll c concentrations. Linear regression analysis revealed a positive correlation between morphometric characteristics and body weight. However, multiple linear regression analysis indicated a negative relationship between body weight and telson length (TEL) and opisthosoma width (OW) of males, as well as TEL of females. The size at which 50 % of the HSC population reached maturity (L50) was estimated to be 12.2 cm for males and 13.5 cm for females based on prosomal width (PW). The average PW measurements of HSC at different egg stages (1–4) from developing to mature females was 14.4 cm, with corresponding body weights ranging from 224 to 243 g. Females at egg of stages 3 and 4 were found throughout the year, indicating multiple spawning events, particularly prevalent in January-April, and predominantly abundant at stations 1, 2, 5 and 6. HSC primarily consumed bivalves (22.1±21.2 %), followed by fishes (5.9±13.0 %) and crustaceans (2.9±9.0 %) by volumetric contribution (%V). This comprehensive study provides novel insights into the population dynamics and feeding ecology of HSC within Thailand. The findings establish a foundational framework for future research endeavors and offer critical data to inform the management and conservation of their habitats.
{"title":"Population structure and feeding habits of Carcinoscorpius rotundicauda in the bay environment, Southern Gulf of Thailand","authors":"Sukree Hajisamae , Kay Khine Soe , Sofiyudin Maae , Saweit Chaymongkol , Akbar John","doi":"10.1016/j.fishres.2024.107216","DOIUrl":"10.1016/j.fishres.2024.107216","url":null,"abstract":"<div><div>This study presents the first comprehensive assessment of the population structure and feeding habits of <em>Carcinoscorpius rotundicauda</em> in Thailand. Sample collection was conducted using crab gill nets at seven sampling sites characterized by distinct ecosystem attributes in Pattani Bay between February 2019 and March 2020. Our findings indicate the presence of a single Asian horseshoe crab (HSC) species within the bay, with a sex ratio of approximately 1:1 (48.1 % males, 51.9 % females) that did not deviate significantly from parity. Habitat variation within the bay did not influence HSC abundance (P > 0.05) whereas monthly abundance fluctuations were highly significant (P < 0.001), peaking in March and reaching the lowest in September. Positive correlations were observed between HSC abundance and environmental factors including dissolved oxygen, temperature, water pH, water depth, and chlorophyll c concentrations. Linear regression analysis revealed a positive correlation between morphometric characteristics and body weight. However, multiple linear regression analysis indicated a negative relationship between body weight and telson length (TEL) and opisthosoma width (OW) of males, as well as TEL of females. The size at which 50 % of the HSC population reached maturity (L<sub>50</sub>) was estimated to be 12.2 cm for males and 13.5 cm for females based on prosomal width (PW). The average PW measurements of HSC at different egg stages (1–4) from developing to mature females was 14.4 cm, with corresponding body weights ranging from 224 to 243 g. Females at egg of stages 3 and 4 were found throughout the year, indicating multiple spawning events, particularly prevalent in January-April, and predominantly abundant at stations 1, 2, 5 and 6. HSC primarily consumed bivalves (22.1±21.2 %), followed by fishes (5.9±13.0 %) and crustaceans (2.9±9.0 %) by volumetric contribution (%V). This comprehensive study provides novel insights into the population dynamics and feeding ecology of HSC within Thailand. The findings establish a foundational framework for future research endeavors and offer critical data to inform the management and conservation of their habitats.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"281 ","pages":"Article 107216"},"PeriodicalIF":2.2,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572890","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}
Pub Date : 2024-11-01DOI: 10.1016/j.fishres.2024.107218
Zhi Cao , Guoping Zhu
Fish belonging to the Nototheniidae family are considered to be the most significant members of the Notothenioids family and are essential to the Antarctic marine ecology. However, the trophic dynamics of some unexploited species, including semi-pelagic painted notothen Lepidonotothen larseni, remains unknown. This study used fatty acids (FAs) and stable isotope indicators to examine the shift in diet from early juvenile to adult stages at South Georgia throughout winter in order to improve our understanding of the dietary diversity and trophic niche of L. larseni. Thirty different types of fatty acids were found in the muscular tissues of early juveniles (4.10–4.85 cm) and adults (8.7–14.9 cm), yet there was a notable variation in the composition of FAs between the two groups. FAs including C22:6n3, C22:2n6, C16:1n7, and C20:5n3 were found in high amounts in both early juveniles and adults. Both the δ15N and δ13C values of adults were significantly higher than those of early juveniles, suggesting an ontogenetic shift in L. larseni's diet and trophic niche separation between the two stages of development. Significant separation in marker FAs was also observed between early juveniles and adults. Early juvenile L. larseni primarily fed on pelagic algae or copepods, whereas adults predominantly fed on Antarctic krill (Euphausia superba) on the seafloor and in the water column.
{"title":"Using fatty acids and stable isotope analyses to elucidate ontogenetic variations in diet of painted notothen Lepidonotothen larseni during winter at the South Georgia shelf, Antarctic","authors":"Zhi Cao , Guoping Zhu","doi":"10.1016/j.fishres.2024.107218","DOIUrl":"10.1016/j.fishres.2024.107218","url":null,"abstract":"<div><div>Fish belonging to the Nototheniidae family are considered to be the most significant members of the Notothenioids family and are essential to the Antarctic marine ecology. However, the trophic dynamics of some unexploited species, including semi-pelagic painted notothen <em>Lepidonotothen larseni</em>, remains unknown. This study used fatty acids (FAs) and stable isotope indicators to examine the shift in diet from early juvenile to adult stages at South Georgia throughout winter in order to improve our understanding of the dietary diversity and trophic niche of <em>L. larseni</em>. Thirty different types of fatty acids were found in the muscular tissues of early juveniles (4.10–4.85 cm) and adults (8.7–14.9 cm), yet there was a notable variation in the composition of FAs between the two groups. FAs including C22:6n3, C22:2n6, C16:1n7, and C20:5n3 were found in high amounts in both early juveniles and adults. Both the δ<sup>15</sup>N and δ<sup>13</sup>C values of adults were significantly higher than those of early juveniles, suggesting an ontogenetic shift in <em>L. larseni</em>'s diet and trophic niche separation between the two stages of development. Significant separation in marker FAs was also observed between early juveniles and adults. Early juvenile <em>L. larseni</em> primarily fed on pelagic algae or copepods, whereas adults predominantly fed on Antarctic krill (<em>Euphausia superba</em>) on the seafloor and in the water column.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"281 ","pages":"Article 107218"},"PeriodicalIF":2.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572887","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}
Pub Date : 2024-11-01DOI: 10.1016/j.fishres.2024.107210
Oanh Thi Truong , Sang Quang Tran , Kent E. Carpenter , Quyen Dang Ha Vu , Thuy-Yen Duong , Mie Mie Kyaw , Chaiwut Grudpan , Van Ngo Thai Bich , Binh Thuy Dang
The spotted spiny eel, Macrognathus siamensis is an economically important freshwater fish in the Mekong River basin, which is undergoing dramatic biodiversity changes due to anthropogenic impacts. The species is non-migratory, with a moderate larval duration that facilitates downstream genetic connectivity. Restriction site-associated DNA sequence datasets that includes 3736 and 1244 single nucleotide polymorphisms representing putatively neutral loci, from all geographic sites and without the Tachileik site, indicate strong population structure in this sedentary fish, with a significant isolation-by-distance signature. This structure reflects isolation of tributary populations and downstream dispersal of these distinct populations to mix in the Mekong mainstem and contributes to increased genetic diversity in the lower reaches of the Mekong basin. Genetic data indicates that the dispersal of eggs and larvae downstream is not impeded by Khone Falls and that the falls prevent upstream dispersal of eggs and larvae. Despite this downstream connectivity, there is a strong population structure among above- and below-Khone Falls groups. An analysis of outlier loci putatively under selection provides evidence that the difference between connected metapopulations above and below the falls is due to the fundamental differences in environmental regimes. We hypothesize that instead of a physical barrier, the falls simply represents a demarcation between previously recognized upstream limited-floodplain environments and downstream extensive-floodplain environments. These findings emphasize the need to monitor genetic diversity of key sedentary fishery species to assess whether proposed dams along the river could affect genetic diversity downstream. This genetic diversity is particularly important for the resilience of downstream populations because of the many environmental impacts caused by dams, land use, and climate change. Early detection of reduced downstream genetic diversity could trigger remediation programs to ensure resilience and continued fisheries productivity of important non-migratory fish resources.
斑棘鳗（Macrognathus siamensis）是湄公河流域一种具有重要经济价值的淡水鱼，由于人类活动的影响，湄公河流域的生物多样性正在发生巨大变化。该物种为非迁徙性鱼类，幼体持续时间适中，有利于下游遗传连接。与限制位点相关的 DNA 序列数据集包括来自所有地理位点的 3736 个和 1244 个单核苷酸多态性，这些数据集代表了假定的中性位点，但不包括 Tachileik 位点。这种结构反映了支流种群的隔离，以及这些不同种群向下游扩散，在湄公河干流混合的情况，并导致湄公河流域下游遗传多样性的增加。遗传数据表明，卵和幼虫向下游的扩散没有受到科纳瀑布的阻碍，而瀑布则阻止了卵和幼虫向上游的扩散。尽管存在下游连通性，但在科纳瀑布以上和以下的群体之间存在着很强的种群结构。对可能处于选择过程中的离群位点的分析表明，瀑布上下相连的元种群之间的差异是由于环境制度的根本不同造成的。我们推测，瀑布并不是一个物理屏障，它只是代表了以前公认的上游有限洪泛平原环境与下游广阔洪泛平原环境之间的分界线。这些发现强调了监测主要定居渔业物种遗传多样性的必要性，以评估沿河拟建大坝是否会影响下游的遗传多样性。由于大坝、土地利用和气候变化造成的诸多环境影响，遗传多样性对下游种群的恢复能力尤为重要。及早发现下游遗传多样性的减少，可以启动补救计划，确保重要的非洄游鱼类资源的恢复能力和持续的渔业生产力。
{"title":"Population genetics of Macrognathus siamenis (Synbranchiformes: Mastacembelidae): Implications for non-migratory fishery resources in the Mekong River basin","authors":"Oanh Thi Truong , Sang Quang Tran , Kent E. Carpenter , Quyen Dang Ha Vu , Thuy-Yen Duong , Mie Mie Kyaw , Chaiwut Grudpan , Van Ngo Thai Bich , Binh Thuy Dang","doi":"10.1016/j.fishres.2024.107210","DOIUrl":"10.1016/j.fishres.2024.107210","url":null,"abstract":"<div><div>The spotted spiny eel, <em>Macrognathus siamensis</em> is an economically important freshwater fish in the Mekong River basin, which is undergoing dramatic biodiversity changes due to anthropogenic impacts. The species is non-migratory, with a moderate larval duration that facilitates downstream genetic connectivity. Restriction site-associated DNA sequence datasets that includes 3736 and 1244 single nucleotide polymorphisms representing putatively neutral loci, from all geographic sites and without the Tachileik site, indicate strong population structure in this sedentary fish, with a significant isolation-by-distance signature. This structure reflects isolation of tributary populations and downstream dispersal of these distinct populations to mix in the Mekong mainstem and contributes to increased genetic diversity in the lower reaches of the Mekong basin. Genetic data indicates that the dispersal of eggs and larvae downstream is not impeded by Khone Falls and that the falls prevent upstream dispersal of eggs and larvae. Despite this downstream connectivity, there is a strong population structure among above- and below-Khone Falls groups. An analysis of outlier loci putatively under selection provides evidence that the difference between connected metapopulations above and below the falls is due to the fundamental differences in environmental regimes. We hypothesize that instead of a physical barrier, the falls simply represents a demarcation between previously recognized upstream limited-floodplain environments and downstream extensive-floodplain environments. These findings emphasize the need to monitor genetic diversity of key sedentary fishery species to assess whether proposed dams along the river could affect genetic diversity downstream. This genetic diversity is particularly important for the resilience of downstream populations because of the many environmental impacts caused by dams, land use, and climate change. Early detection of reduced downstream genetic diversity could trigger remediation programs to ensure resilience and continued fisheries productivity of important non-migratory fish resources.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"281 ","pages":"Article 107210"},"PeriodicalIF":2.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572888","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}
Pub Date : 2024-10-30DOI: 10.1016/j.fishres.2024.107214
Peter Ljungberg , Sven-Gunnar Lunneryd , Lars Hillström , Glenn Fridh , Mikael Lundin
Trap nets are a large, stationary, and fixed type of passive fishing gear that has traditionally been used for catching fish in shallow coastal environments. Despite their large size, catches are often retrieved using small boats, making them less energy demanding compared to active gear types. This, along with the stationary nature of the trap, allows for fishing with relatively low environmental impact due to minimal disturbance of the benthic community. The combination of minimal benthic impact, live catch, low fuel, and selectivity offers great potential for the development of sustainable coastal fisheries.
Here, we describe the development of the hovering pontoon trap, a fishing gear with a robust design to resist strong waves and currents, and usable in both shallow and deep waters to catch both pelagic and benthic species. We present results from early case studies targeting benthic Baltic Sea species, including perch (Percha fluventaliis), Atlantic cod (Gadus morhua) and vendace (Coregonus albula), showing similar or improved catches in relation to earlier studies. Further, we show that the hovering pontoon trap was able to withstand harsher conditions than previous bottom-set models, making it a possible solution for the targeting of benthic fish communities in coastal environments.
{"title":"The hovering pontoon trap: The tougher, younger sibling in the pontoon trap family","authors":"Peter Ljungberg , Sven-Gunnar Lunneryd , Lars Hillström , Glenn Fridh , Mikael Lundin","doi":"10.1016/j.fishres.2024.107214","DOIUrl":"10.1016/j.fishres.2024.107214","url":null,"abstract":"<div><div>Trap nets are a large, stationary, and fixed type of passive fishing gear that has traditionally been used for catching fish in shallow coastal environments. Despite their large size, catches are often retrieved using small boats, making them less energy demanding compared to active gear types. This, along with the stationary nature of the trap, allows for fishing with relatively low environmental impact due to minimal disturbance of the benthic community. The combination of minimal benthic impact, live catch, low fuel, and selectivity offers great potential for the development of sustainable coastal fisheries.</div><div>Here, we describe the development of the hovering pontoon trap, a fishing gear with a robust design to resist strong waves and currents, and usable in both shallow and deep waters to catch both pelagic and benthic species. We present results from early case studies targeting benthic Baltic Sea species, including perch (<em>Percha fluventaliis</em>), Atlantic cod (<em>Gadus morhua</em>) and vendace (<em>Coregonus albula</em>), showing similar or improved catches in relation to earlier studies. Further, we show that the hovering pontoon trap was able to withstand harsher conditions than previous bottom-set models, making it a possible solution for the targeting of benthic fish communities in coastal environments.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"281 ","pages":"Article 107214"},"PeriodicalIF":2.2,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554150","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}
In the light of reducing the impact of fishery, artisanal fisheries hold great potential to achieve the sustainable use of marine resources if locally managed at sub-regional level (i.e., within the same province or fleet) and by implementing mitigation systems. The Chioggia small-scale fishing fleet represents a study case in an overexploited Mediterranean sub-region, operating both in the Venice Lagoon and the North Adriatic Sea. During the spawning period, this small-scale fishery targets the same target species, the common cuttlefish (Sepia officinalis), which, over the past thirty years, has shown a general decline in catch trends. Cuttlefish represent a high-value resource at all life stages, with both adults and juveniles considered targets of the artisanal fishery. Additionally, eggs are consistently laid on fishing gear during the breeding season and must be removed by fishers to prevent a reduction in fishing efficiency. These aspects contribute to the vulnerability of the common cuttlefish stocks, calling for a complementary management approach. We researched methods from the peer-reviewed literature, and adapted methods to reflect the environmental conditions of the sea and lagoon, and small-scale fishing methods. We combined into a complementary management approach: i) mitigation systems to reduce and collect eggs discarded during fishing operations, ii) semi-natural juvenile rearing diets to potentially release fishing pressure and support natural population, and iii) small-scale supply chain to both raise awareness about this resource vulnerability and promote the activity of fishers adopting virtuous behaviours. We tested these three functional management units in collaboration with lagoon and sea fishers and local stakeholders. We showed that the use of egg collectors, as an alternative spawning structure, performed well to limit the loss of the eggs laid upon the fishing gears. Second, we showed that Mixed and Natural diets contributed significantly to the growth rate of hatchlings compared to artificial diets. Finally, we demonstrated a shared interest in products derived from sustainable fisheries from the public, fishers and retailers. Therefore, the small-scale supply chain can represent a valid component to valorise the adoption of the whole management scheme. Overall, this complementary management approach can be adapted to and implemented in other local socio-economic communities of artisanal fishing in coastal environments worldwide. Complementary mitigation systems could work in synergy, overcoming the limitations of individual mitigation measures applied to diverse fishery resources.
{"title":"Implementing a fishery improvement programme to manage the common cuttlefish (Sepia officinalis) in artisanal sea and lagoon fisheries: The case study of the Chioggia’s fleet","authors":"Emily Sepe , Federica Poli , Federico Calì , Simone D’Acunto , Carlotta Mazzoldi , Matteo Barbato","doi":"10.1016/j.fishres.2024.107209","DOIUrl":"10.1016/j.fishres.2024.107209","url":null,"abstract":"<div><div>In the light of reducing the impact of fishery, artisanal fisheries hold great potential to achieve the sustainable use of marine resources if locally managed at sub-regional level (i.e., within the same province or fleet) and by implementing mitigation systems. The Chioggia small-scale fishing fleet represents a study case in an overexploited Mediterranean sub-region, operating both in the Venice Lagoon and the North Adriatic Sea. During the spawning period, this small-scale fishery targets the same target species, the common cuttlefish (<em>Sepia officinalis</em>), which, over the past thirty years, has shown a general decline in catch trends. Cuttlefish represent a high-value resource at all life stages, with both adults and juveniles considered targets of the artisanal fishery. Additionally, eggs are consistently laid on fishing gear during the breeding season and must be removed by fishers to prevent a reduction in fishing efficiency. These aspects contribute to the vulnerability of the common cuttlefish stocks, calling for a complementary management approach. We researched methods from the peer-reviewed literature, and adapted methods to reflect the environmental conditions of the sea and lagoon, and small-scale fishing methods. We combined into a complementary management approach: i) mitigation systems to reduce and collect eggs discarded during fishing operations, ii) semi-natural juvenile rearing diets to potentially release fishing pressure and support natural population, and iii) small-scale supply chain to both raise awareness about this resource vulnerability and promote the activity of fishers adopting virtuous behaviours. We tested these three functional management units in collaboration with lagoon and sea fishers and local stakeholders. We showed that the use of egg collectors, as an alternative spawning structure, performed well to limit the loss of the eggs laid upon the fishing gears. Second, we showed that Mixed and Natural diets contributed significantly to the growth rate of hatchlings compared to artificial diets. Finally, we demonstrated a shared interest in products derived from sustainable fisheries from the public, fishers and retailers. Therefore, the small-scale supply chain can represent a valid component to valorise the adoption of the whole management scheme. Overall, this complementary management approach can be adapted to and implemented in other local socio-economic communities of artisanal fishing in coastal environments worldwide. Complementary mitigation systems could work in synergy, overcoming the limitations of individual mitigation measures applied to diverse fishery resources.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"281 ","pages":"Article 107209"},"PeriodicalIF":2.2,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554151","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}
Pub Date : 2024-10-23DOI: 10.1016/j.fishres.2024.107199
P. Leitão , A. Campos , M. Castro
Knowledge of the gear used in multi-gear fisheries is crucial for supporting fisheries management. Still, the high complexity and lack of data in the Portuguese multi-gear coastal fleet compromise this task. The present study developed a method to predict main fishing gear used in each fishing trip for the Portuguese multi-gear coastal fleet based on landing records (species caught, port, and month of landing). Landing records were used to predict gear (available for part of the fleet with electronic logbooks) using a machine learning model (random forest). This model was then applied to the remaining trips of the fleet, without electronic logbooks, to predict the gear used. A total of six gear types were considered: bivalve dredges, traps, gillnets, trammel nets, drifting longlines, and bottom longlines. The overall model prediction error was 14 %; bivalve dredges and longlines had the lowest errors, and trammel nets and gillnets were the highest. The study sheds new light on important aspects of the dynamics of this fleet, namely a decreasing trend in the use of longlines, poor electronic logbook coverage for some gear types, and greater diversity in the catches obtained with nets compared to other gear types.
{"title":"Predicting gear used in a multi-gear coastal fleet","authors":"P. Leitão , A. Campos , M. Castro","doi":"10.1016/j.fishres.2024.107199","DOIUrl":"10.1016/j.fishres.2024.107199","url":null,"abstract":"<div><div>Knowledge of the gear used in multi-gear fisheries is crucial for supporting fisheries management. Still, the high complexity and lack of data in the Portuguese multi-gear coastal fleet compromise this task. The present study developed a method to predict main fishing gear used in each fishing trip for the Portuguese multi-gear coastal fleet based on landing records (species caught, port, and month of landing). Landing records were used to predict gear (available for part of the fleet with electronic logbooks) using a machine learning model (random forest). This model was then applied to the remaining trips of the fleet, without electronic logbooks, to predict the gear used. A total of six gear types were considered: bivalve dredges, traps, gillnets, trammel nets, drifting longlines, and bottom longlines. The overall model prediction error was 14 %; bivalve dredges and longlines had the lowest errors, and trammel nets and gillnets were the highest. The study sheds new light on important aspects of the dynamics of this fleet, namely a decreasing trend in the use of longlines, poor electronic logbook coverage for some gear types, and greater diversity in the catches obtained with nets compared to other gear types.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"281 ","pages":"Article 107199"},"PeriodicalIF":2.2,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528964","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}
Pub Date : 2024-10-22DOI: 10.1016/j.fishres.2024.107202
Marta M. Rufino , Catarina Maia , David Dinis , Inês Farias , Teresa Moura , Pedro Gomes , Ivania Quaresma , Rogélia Martins , Ivone Figueiredo , Bárbara Serra-Pereira , Miguel B. Gaspar , Ana Moreno
Although coastal areas are of great importance, they often lack long term monitoring surveys, which are essential for effective management, fisheries sustainability, and marine spatial planning. To address this, we conducted two experimental surveys aimed at assessing communities and their biodiversity, with the objective of designing a monitoring program for marine coastal biodiversity, based on gear type, depth, sampling arrangement, total net length, and panel position within the haul. Depth was found to be the most important factor shaping biodiversity, while gear type had the greatest impact on assessing species richness. Overall, both number of species and diversity increased with depth, though significant differences were only found between hauls deployed at 10 m and deeper (30–50 m). Trammel nets caught a larger number of species compared to gillnets, and there was evidence of an interaction between depth and gear, in terms of abundance and at the community level; samples taken deeper than 10 m showed more gear-related differences. We found that neither the panel position within the haul nor the number of nets had any impact on species diversity or abundance. Similarly, there was no evidence for an effect related to the arrangement of nets, as results were consistent whether using separated or continuous net panels. However, the number of nets used as a sampling unit significantly influenced the results, as the variation in species abundance and diversity with depth and gear type was similar, when 20 or 30 nets were used, but became more variable when only 10 nets were used, even with increased replication. We concluded that both trammel nets and gillnets should be included in a coastal biodiversity monitoring program, as each catches a different set of species, including both demersal and pelagic taxa. Further, we recommend using a minimum of 20 nets (ideally 30+) per station, with replication. The evaluated monitoring system has a minimal impact on the ecosystem, can be easily deployed using commercial vessels and effectively captures a large number of species, being thus, highly recommended to be used in coastal monitoring surveys.
{"title":"Designing a coastal monitoring marine biodiversity survey, using trammel nets and gillnets in Portugal","authors":"Marta M. Rufino , Catarina Maia , David Dinis , Inês Farias , Teresa Moura , Pedro Gomes , Ivania Quaresma , Rogélia Martins , Ivone Figueiredo , Bárbara Serra-Pereira , Miguel B. Gaspar , Ana Moreno","doi":"10.1016/j.fishres.2024.107202","DOIUrl":"10.1016/j.fishres.2024.107202","url":null,"abstract":"<div><div>Although coastal areas are of great importance, they often lack long term monitoring surveys, which are essential for effective management, fisheries sustainability, and marine spatial planning. To address this, we conducted two experimental surveys aimed at assessing communities and their biodiversity, with the objective of designing a monitoring program for marine coastal biodiversity, based on gear type, depth, sampling arrangement, total net length, and panel position within the haul. Depth was found to be the most important factor shaping biodiversity, while gear type had the greatest impact on assessing species richness. Overall, both number of species and diversity increased with depth, though significant differences were only found between hauls deployed at 10 m and deeper (30–50 m). Trammel nets caught a larger number of species compared to gillnets, and there was evidence of an interaction between depth and gear, in terms of abundance and at the community level; samples taken deeper than 10 m showed more gear-related differences. We found that neither the panel position within the haul nor the number of nets had any impact on species diversity or abundance. Similarly, there was no evidence for an effect related to the arrangement of nets, as results were consistent whether using separated or continuous net panels. However, the number of nets used as a sampling unit significantly influenced the results, as the variation in species abundance and diversity with depth and gear type was similar, when 20 or 30 nets were used, but became more variable when only 10 nets were used, even with increased replication. We concluded that both trammel nets and gillnets should be included in a coastal biodiversity monitoring program, as each catches a different set of species, including both demersal and pelagic taxa. Further, we recommend using a minimum of 20 nets (ideally 30+) per station, with replication. The evaluated monitoring system has a minimal impact on the ecosystem, can be easily deployed using commercial vessels and effectively captures a large number of species, being thus, highly recommended to be used in coastal monitoring surveys.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"281 ","pages":"Article 107202"},"PeriodicalIF":2.2,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528963","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}
Pub Date : 2024-10-18DOI: 10.1016/j.fishres.2024.107205
Dante Queirolo , Mauricio Ahumada , Marcelo A. San Martín , Catalina Román , Tomás Araya-Schmidt , Pedro Apablaza , Claudio Bernal
In recent years, the Chilean hake (Merluccius gayi gayi) trawl fishery has implemented measures to reduce discards, bycatch, and incidental captures. In the past ten years, the incidental capture of South American sea lions (Otaria flavescens) (SASLs) has become a significant concern, particularly for the small-scale fleet operating from San Antonio in central Chile. To address this issue, a sea lion exclusion device (SLED) was introduced for trawl nets. This paper describes an experiment that was designed to assess the effectiveness of SLEDs. Records of the incidental capture of SASLs and mortality from scientific observers monitoring this small-scale trawl fleet were also analyzed. The results of the experiment indicated that SLEDs greatly reduced incidental captures of SASLs without affecting the capture of the target species. However, given that there was only one year of overlap between non-SLED and SLED data, these findings should be interpreted with caution. The data from scientific observers from 2015 to 2022 suggested a consistent decrease in the incidental capture of SASLs with the use of SLEDs, supporting the potential effectiveness of this mitigation measure.
{"title":"Testing and implementation of an exclusion device for mitigating the incidental capture of sea lions in the Chilean small-scale trawl hake fishery","authors":"Dante Queirolo , Mauricio Ahumada , Marcelo A. San Martín , Catalina Román , Tomás Araya-Schmidt , Pedro Apablaza , Claudio Bernal","doi":"10.1016/j.fishres.2024.107205","DOIUrl":"10.1016/j.fishres.2024.107205","url":null,"abstract":"<div><div>In recent years, the Chilean hake (<em>Merluccius gayi gayi</em>) trawl fishery has implemented measures to reduce discards, bycatch, and incidental captures. In the past ten years, the incidental capture of South American sea lions (<em>Otaria flavescens</em>) (SASLs) has become a significant concern, particularly for the small-scale fleet operating from San Antonio in central Chile. To address this issue, a sea lion exclusion device (SLED) was introduced for trawl nets. This paper describes an experiment that was designed to assess the effectiveness of SLEDs. Records of the incidental capture of SASLs and mortality from scientific observers monitoring this small-scale trawl fleet were also analyzed. The results of the experiment indicated that SLEDs greatly reduced incidental captures of SASLs without affecting the capture of the target species. However, given that there was only one year of overlap between non-SLED and SLED data, these findings should be interpreted with caution. The data from scientific observers from 2015 to 2022 suggested a consistent decrease in the incidental capture of SASLs with the use of SLEDs, supporting the potential effectiveness of this mitigation measure.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"281 ","pages":"Article 107205"},"PeriodicalIF":2.2,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528961","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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