The durability of animal parts that are collected and traded as trophies has an impact on species sustainability, especially when animals are slow-growing, have low fecundity, or are particularly vulnerable to capture. CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora), aims to control the trade of wild fauna and flora specifically by using trade restrictions as a policy option. However, specialists in international trade have advised against using trade restrictions to correct social cost issues. The reasons for this advice have to do with the unintended economic consequences of animals being placed on an endangered species list, coupled with the trade restrictions themselves. We focused on Pristis spp. (sawfish), a species in danger of extinction found in Appendix I of the CITES convention. An extensive search of sawfish saws for sale on the internet was performed during 2016 and 2017. A total of 174 observations of market prices were collected. We estimated several models linking prices to the size of the saw with other variables that might explain price variability using OLS regression, and which included data from both the original internet searches and additional variables, including a dummy variable which indicated the year in which the species group was placed in Appendix I. These models show that rather than slow down the extinction pathway for this species, CITES may have sped it up, as well as driving the sawfish trophy markets underground.
{"title":"Do CITES trade restrictions work? Some evidence from the markets for sawfish trophies","authors":"Santiago Gómez-Rodríguez, James R. Wilson","doi":"10.1051/alr/2022003","DOIUrl":"https://doi.org/10.1051/alr/2022003","url":null,"abstract":"The durability of animal parts that are collected and traded as trophies has an impact on species sustainability, especially when animals are slow-growing, have low fecundity, or are particularly vulnerable to capture. CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora), aims to control the trade of wild fauna and flora specifically by using trade restrictions as a policy option. However, specialists in international trade have advised against using trade restrictions to correct social cost issues. The reasons for this advice have to do with the unintended economic consequences of animals being placed on an endangered species list, coupled with the trade restrictions themselves. We focused on Pristis spp. (sawfish), a species in danger of extinction found in Appendix I of the CITES convention. An extensive search of sawfish saws for sale on the internet was performed during 2016 and 2017. A total of 174 observations of market prices were collected. We estimated several models linking prices to the size of the saw with other variables that might explain price variability using OLS regression, and which included data from both the original internet searches and additional variables, including a dummy variable which indicated the year in which the species group was placed in Appendix I. These models show that rather than slow down the extinction pathway for this species, CITES may have sped it up, as well as driving the sawfish trophy markets underground.","PeriodicalId":55491,"journal":{"name":"Aquatic Living Resources","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57824445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study sheds light on challenges and possibilities for the German aquaculture sector resulting from the restrictions imposed by the German government to contain the Coronavirus SARS-CoV-2. By presenting results of expert interviews, stakeholder statements and a survey among German fish farmers, we provide insights into distribution, cost and turnover developments trigged by the restrictions in 2020. The survey shows that the pandemic had an impact on the business of a large group of producers: 44% of the fish farmers reported disturbed production processes, 46% experienced a decline in sales and the restricted gastronomy sector impacted negatively on the sales of 79%. On the other hand, 15% of the respondents were able to sell more than in 2019, 27% expanded their sales directly to the consumers. Nevertheless, a great majority (78%) did not perceive the impact of the Covid-19 pandemic as the main challenge of German aquaculture. Based on the gained insights, we estimated the economic impacts of the Covid-19 restrictions on typical German fish farms under three scenarios with EBIT changes ranging from −10% to +8% compared to 2019. In that way, the gained insights teach valuable lessons on the sector's resilience to external shocks. During the scenarios a lack of vertical integration and a dependency on wholesale led to financial challenges. On the other hand, the scenarios attest fish farms with direct marketing structures and diversified distribution channels a higher resilience to external shocks: the small-scale structure of the German aquaculture that was often seen as a weakness on a globalised market proved to be an advantage.
{"title":"German aquaculture under Covid-19 – impacts of the pandemic on the sector during 2020","authors":"Lina-Marie Huber, T. Lasner","doi":"10.1051/alr/2022019","DOIUrl":"https://doi.org/10.1051/alr/2022019","url":null,"abstract":"This study sheds light on challenges and possibilities for the German aquaculture sector resulting from the restrictions imposed by the German government to contain the Coronavirus SARS-CoV-2. By presenting results of expert interviews, stakeholder statements and a survey among German fish farmers, we provide insights into distribution, cost and turnover developments trigged by the restrictions in 2020. The survey shows that the pandemic had an impact on the business of a large group of producers: 44% of the fish farmers reported disturbed production processes, 46% experienced a decline in sales and the restricted gastronomy sector impacted negatively on the sales of 79%. On the other hand, 15% of the respondents were able to sell more than in 2019, 27% expanded their sales directly to the consumers. Nevertheless, a great majority (78%) did not perceive the impact of the Covid-19 pandemic as the main challenge of German aquaculture. Based on the gained insights, we estimated the economic impacts of the Covid-19 restrictions on typical German fish farms under three scenarios with EBIT changes ranging from −10% to +8% compared to 2019. In that way, the gained insights teach valuable lessons on the sector's resilience to external shocks. During the scenarios a lack of vertical integration and a dependency on wholesale led to financial challenges. On the other hand, the scenarios attest fish farms with direct marketing structures and diversified distribution channels a higher resilience to external shocks: the small-scale structure of the German aquaculture that was often seen as a weakness on a globalised market proved to be an advantage.","PeriodicalId":55491,"journal":{"name":"Aquatic Living Resources","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57824855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The narrow-clawed crayfish (Pontastacus leptodactylus) is one of the most ecologically and economically important freshwater species in Turkey. However, the harvest of this species has declined from 7937 t in 1984 to 696 t in 2019. One of primary reasons for this decrease in stock is the use of fishing gears with poor size selectivity. In this study, new codend designs were investigated to improve the size selectivity of fyke nets for P. leptodactylus. Seven codends of three different designs were tested: (1) a commercially used standard codend with 34 mm mesh size (Com34); (2) sorting grids with 20 (SG20), 25 (SG25) and 30 mm (SG30) bar spacing attached to the last circle of the net; and (3) a stiff rigged net, the last part of the fyke nets (codend) with 34 (SRN34), 42 (SRN42) and 50 mm (SRN50) mesh size. The average length at 50% retention probability (L50) and selection range (SR) (L75–L25) values of Com34 were 9.4 cm and 3.1 cm, respectively. For the SG20, SG25 and SG30 grids, the L50 values were 11.3 cm, 11.6 cm and 12.0 cm, while the SR values were 1.4 cm, 1.3 cm and 0.6 cm, respectively. For the SRN34, SRN42 and SRN50 codends, the L50 values were 10.9 cm, 11.6 cm and 11.6 cm, while the SR values were 2.1 cm, 2.1cm and 1.1 cm, respectively. Overall, the commercial codend resulted in lower L50 values when the minimum conservation reference length of 10 cm was considered. However, all tested new codend designs showed improved selectivity compared with the standard, with optimum results obtained with SG20. SG20 grid decreased discarding by 15.7% compared to the classic commercial fyke net; thus, this is a very important result for the sustainability of natural P. leptodactylus stocks.
窄爪小龙虾(Pontastacus leptodactylus)是土耳其最重要的生态和经济淡水物种之一。然而，该物种的收获量从1984年的7937吨下降到2019年的696吨。鱼类数量减少的主要原因之一是使用了尺寸选择性差的渔具。本研究探讨了新的码尾设计，以提高对细趾假单足虫网具的大小选择性。测试了三种不同设计的七种码头:(1)商用标准码头，网目尺寸为34 mm (Com34);(2)在网的最后一圈附着20 (SG20)、25 (SG25)和30 mm (SG30)棒距的分选网格;(3)硬式吊网，最后一部分的网目尺寸分别为34 (SRN34)、42 (SRN42)和50 mm (SRN50)。Com34在50%保留概率下的平均长度(L50)和选择范围(SR) (l75 ~ l25)分别为9.4 cm和3.1 cm。对于SG20、SG25和SG30栅格，L50值分别为11.3、11.6和12.0 cm, SR值分别为1.4、1.3和0.6 cm。SRN34、SRN42和SRN50的L50值分别为10.9 cm、11.6 cm和11.6 cm, SR值分别为2.1cm、2.1cm和1.1 cm。总体而言，当考虑最小保护参考长度为10 cm时，商业规范导致L50值较低。然而，与标准相比，所有测试的新编码端设计都显示出更高的选择性，其中SG20获得了最佳结果。与传统的商业电网相比，SG20电网的丢弃量减少了15.7%;因此，这是一个非常重要的结果，对自然的纤毛霉种群的可持续性。
{"title":"New codend designs to improve the size selectivity of fyke net for narrow-clawed crayfish (Pontastacus leptodactylus)","authors":"Mehmet Cìlbìz, Celalettin Aydın, B. Herrmann","doi":"10.1051/alr/2022014","DOIUrl":"https://doi.org/10.1051/alr/2022014","url":null,"abstract":"The narrow-clawed crayfish (Pontastacus leptodactylus) is one of the most ecologically and economically important freshwater species in Turkey. However, the harvest of this species has declined from 7937 t in 1984 to 696 t in 2019. One of primary reasons for this decrease in stock is the use of fishing gears with poor size selectivity. In this study, new codend designs were investigated to improve the size selectivity of fyke nets for P. leptodactylus. Seven codends of three different designs were tested: (1) a commercially used standard codend with 34 mm mesh size (Com34); (2) sorting grids with 20 (SG20), 25 (SG25) and 30 mm (SG30) bar spacing attached to the last circle of the net; and (3) a stiff rigged net, the last part of the fyke nets (codend) with 34 (SRN34), 42 (SRN42) and 50 mm (SRN50) mesh size. The average length at 50% retention probability (L50) and selection range (SR) (L75–L25) values of Com34 were 9.4 cm and 3.1 cm, respectively. For the SG20, SG25 and SG30 grids, the L50 values were 11.3 cm, 11.6 cm and 12.0 cm, while the SR values were 1.4 cm, 1.3 cm and 0.6 cm, respectively. For the SRN34, SRN42 and SRN50 codends, the L50 values were 10.9 cm, 11.6 cm and 11.6 cm, while the SR values were 2.1 cm, 2.1cm and 1.1 cm, respectively. Overall, the commercial codend resulted in lower L50 values when the minimum conservation reference length of 10 cm was considered. However, all tested new codend designs showed improved selectivity compared with the standard, with optimum results obtained with SG20. SG20 grid decreased discarding by 15.7% compared to the classic commercial fyke net; thus, this is a very important result for the sustainability of natural P. leptodactylus stocks.","PeriodicalId":55491,"journal":{"name":"Aquatic Living Resources","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57824744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The physiological response of two species of mussels (Mytilus edulis and M. galloprovincialis) and two species of oysters (Crassostrea gigas and Ostrea edulis) to temperature, oxygen levels and food concentration, factors likely to vary as a result of climate change, was determined experimentally. Bivalves of similar size from different origins were exposed to six temperatures (3, 8, 15, 20, 25 and 30 °C) at two food regimes (2 and 10 μg Chl a L−1) for 6 weeks. In a parallel running experiment M. edulis from the same batches were exposed to three different temperatures (15, 20 and 25 °C) and three different oxygen levels (30, 50 and 100%) at two food regimes (2 and >8 μg Chl a L−1) for 3–4 weeks. Survival during the experiment ranged from 93% to 100% except for the mussels exposed to 30 °C which showed 100% mortality after three to 32 days. Higher food conditions showed higher optimal temperatures for growth of mussels and oysters. In addition, at the high food treatment, reduced O2 saturation resulted in lower growth of mussels. At the low food treatment there were no differences in growth among the different O2 levels at the same temperature. At high food concentration treatment, M. edulis growth was higher with low temperature and high oxygen level. Condition index was higher at higher food concentrations and decreased with increasing temperature. In addition, condition was lower at low oxygen saturation. Lower clearance rates were observed at high food concentrations. At 100% saturation of oxygen, mussel clearance rate increased with temperature at High food regime, but not at Low food regime. Mussel clearance rates were significantly reduced with low oxygen concentrations together with high temperature. Oxygen consumption significantly increased with temperature. Oxygen saturation was the main factor affecting mussel clearance rate. High temperature and low oxygen concentration combined significantly reduced clearance rate and increased oxygen consumption. These response curves can be used to improve parameterisation of individual shellfish growth models taking into consideration factors in the context of climate change: temperature, food concentration, oxygen concentration and their interactions. The observation that abiotic factors interact in affecting mussels and oysters is an important result to take into account.
实验研究了两种贻贝(Mytilus edulis和M. galloprovincialis)和两种牡蛎(Crassostrea gigas和Ostrea edulis)对温度、氧气水平和食物浓度等可能因气候变化而变化的因素的生理反应。研究人员将来自不同来源的大小相似的双壳贝在6个温度(3、8、15、20、25和30°C)和两种食物体系(2和10 μg Chl a L−1)下暴露6周。在平行运行的实验中，将同一批次的毛竹芽孢杆菌暴露在三种不同温度(15、20和25°C)和三种不同氧气水平(30、50和100%)下，在两种食物体系(2和bbb80 μg Chl a L−1)下，持续3-4周。实验期间的存活率为93%至100%，但暴露于30°C的贻贝在3至32天后死亡率为100%。较高的食物条件表明贻贝和牡蛎生长的最佳温度较高。此外，在高食物处理下，氧饱和度降低导致贻贝生长减慢。在低食处理下，相同温度下不同氧含量的植株生长无差异。在高食物浓度处理下，毛竹芽孢杆菌在低温和高氧条件下生长更快。条件指数随食物浓度的升高而升高，随温度的升高而降低。此外，低氧饱和度条件较低。在高浓度食物中观察到较低的清除率。在100%氧饱和度下，高摄食条件下贻贝清除率随温度升高而升高，而低摄食条件下则不升高。低氧和高温条件下贻贝清除率显著降低。耗氧量随温度的升高而显著增加。氧饱和度是影响贻贝清除率的主要因素。高温和低氧浓度的结合显著降低了清除率，增加了耗氧量。这些响应曲线可用于改善单个贝类生长模型的参数化，考虑气候变化背景下的因素:温度、食物浓度、氧气浓度及其相互作用。观察到非生物因素在影响贻贝和牡蛎时相互作用，这是一个值得考虑的重要结果。
{"title":"Interacting climate change effects on mussels (Mytilus edulis and M. galloprovincialis) and oysters (Crassostrea gigas and Ostrea edulis): experiments for bivalve individual growth models","authors":"P. Kamermans, C. Saurel","doi":"10.1051/alr/2022001","DOIUrl":"https://doi.org/10.1051/alr/2022001","url":null,"abstract":"The physiological response of two species of mussels (Mytilus edulis and M. galloprovincialis) and two species of oysters (Crassostrea gigas and Ostrea edulis) to temperature, oxygen levels and food concentration, factors likely to vary as a result of climate change, was determined experimentally. Bivalves of similar size from different origins were exposed to six temperatures (3, 8, 15, 20, 25 and 30 °C) at two food regimes (2 and 10 μg Chl a L−1) for 6 weeks. In a parallel running experiment M. edulis from the same batches were exposed to three different temperatures (15, 20 and 25 °C) and three different oxygen levels (30, 50 and 100%) at two food regimes (2 and >8 μg Chl a L−1) for 3–4 weeks. Survival during the experiment ranged from 93% to 100% except for the mussels exposed to 30 °C which showed 100% mortality after three to 32 days. Higher food conditions showed higher optimal temperatures for growth of mussels and oysters. In addition, at the high food treatment, reduced O2 saturation resulted in lower growth of mussels. At the low food treatment there were no differences in growth among the different O2 levels at the same temperature. At high food concentration treatment, M. edulis growth was higher with low temperature and high oxygen level. Condition index was higher at higher food concentrations and decreased with increasing temperature. In addition, condition was lower at low oxygen saturation. Lower clearance rates were observed at high food concentrations. At 100% saturation of oxygen, mussel clearance rate increased with temperature at High food regime, but not at Low food regime. Mussel clearance rates were significantly reduced with low oxygen concentrations together with high temperature. Oxygen consumption significantly increased with temperature. Oxygen saturation was the main factor affecting mussel clearance rate. High temperature and low oxygen concentration combined significantly reduced clearance rate and increased oxygen consumption. These response curves can be used to improve parameterisation of individual shellfish growth models taking into consideration factors in the context of climate change: temperature, food concentration, oxygen concentration and their interactions. The observation that abiotic factors interact in affecting mussels and oysters is an important result to take into account.","PeriodicalId":55491,"journal":{"name":"Aquatic Living Resources","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57824892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Gérard, M. Hervé, Héloïse Hamel, M. Gay, Michel Barbier, T. Barreau
The starry smooth-hound Mustelus asterias is a near-threatened coastal shark in Europe, whose parasitofauna is largely unknown. We studied metazoan parasites of 20 immature sharks (13 males and seven females) from the English Channel and we examined their relationships with host condition and their use as host bioindicators. All the sharks were parasitized by one to six metazoan taxa among the twelve recorded in the whole sampling (one trematode, six cestodes and two nematodes trophically-transmitted; one monogenean, one copepod and one myxosporean on gills), with a mean abundance of 30.5 ± 21.4 parasites per fish (myxosporeans not included). The three major taxa were in decreasing order: the nematode Acanthocheilus rotundatus (prevalence: 75%, Confidence Interval 53–89%), the cestode Eutetrarhynchus sp. (70%, CI 48–85%), and the monogenean Erpocotyle laevis (60%, CI 39–78%). The gill copepod Kroyeria lineata and the gut nematode Proleptus obtusus were identified as significant pathogens. Parasite community differed between males and females despite their immature stage, suggesting early spatial sex-segregation, with E. laevis, Eutetrarhynchus sp. and Anthobothrium sp. proposed as tags. We discuss results in terms of host fitness loss and information given by parasites on diet ecology and stock discrimination. We recommend incorporating parasitology in further research to improve shark conservation and management.
{"title":"Metazoan parasite community as a potential biological indicator in juveniles of the starry smooth-hound Mustelus asterias Cloquet, 1819 (Carcharhiniformes Triakidae)","authors":"C. Gérard, M. Hervé, Héloïse Hamel, M. Gay, Michel Barbier, T. Barreau","doi":"10.1051/alr/2022002","DOIUrl":"https://doi.org/10.1051/alr/2022002","url":null,"abstract":"The starry smooth-hound Mustelus asterias is a near-threatened coastal shark in Europe, whose parasitofauna is largely unknown. We studied metazoan parasites of 20 immature sharks (13 males and seven females) from the English Channel and we examined their relationships with host condition and their use as host bioindicators. All the sharks were parasitized by one to six metazoan taxa among the twelve recorded in the whole sampling (one trematode, six cestodes and two nematodes trophically-transmitted; one monogenean, one copepod and one myxosporean on gills), with a mean abundance of 30.5 ± 21.4 parasites per fish (myxosporeans not included). The three major taxa were in decreasing order: the nematode Acanthocheilus rotundatus (prevalence: 75%, Confidence Interval 53–89%), the cestode Eutetrarhynchus sp. (70%, CI 48–85%), and the monogenean Erpocotyle laevis (60%, CI 39–78%). The gill copepod Kroyeria lineata and the gut nematode Proleptus obtusus were identified as significant pathogens. Parasite community differed between males and females despite their immature stage, suggesting early spatial sex-segregation, with E. laevis, Eutetrarhynchus sp. and Anthobothrium sp. proposed as tags. We discuss results in terms of host fitness loss and information given by parasites on diet ecology and stock discrimination. We recommend incorporating parasitology in further research to improve shark conservation and management.","PeriodicalId":55491,"journal":{"name":"Aquatic Living Resources","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57824903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Juliana Monteiro da Silva Vieira, P. Costa, A. C. Braga, R. R. São-Clemente, C. Ferreira, Jodir P. Silva
Age, growth and maturity of frigate tuna (Auxis thazard) were studied for the first time in Southeast Brazil. A total of 650 fish (265–494 mm Fork Length) were sampled from beach-seine landings between March 2018 and February 2019. Sectioned fin spines from 548 specimens were processed and age was determined by counting and measuring of increments. Growth parameters were fitted to length-at-age data using the von Bertalanffy growth function and were compared to the literature using the growth performance index (Phi). Macro and microscopic characterization of gonads and physiological indexes were used for the analysis of the reproductive cycle. The length distribution did not differ by sex. Assigned ages were between 0+ and 4 years, with annual increments formed during winter. Coefficient of variation between readings was 11%. Growth differed by sex, and the von Bertalanffy growth parameters were L∞ = 471 mm; k = 0.47 year−1; and t0 = –1.46 year−1 for females; L∞ = 498 mm; k = 0.35 year−1; and t0 = –2.01 year−1 for males. Phi was 5.0 for both sexes. Estimated growth rate is among the lowest recorded for the species, possibly related to the method used for age and growth assessment. Gonadosomatic index peaked in December, associated with the upwelling of the South Atlantic Central Waters, at a temperature of approximately 16 °C. Spawning activity in colder waters has never been reported for this species and may be influenced by a richer habitat caused by the intrusion of more nutritive rich waters during spring-summer, which allows larval development. Length-at-first-maturity (L50) was 345.4 mm for females and 329.8 mm for males.
{"title":"Age, growth and maturity of frigate tuna (Auxis thazard Lacepède, 1800) in the Southeastern Brazilian coast","authors":"Juliana Monteiro da Silva Vieira, P. Costa, A. C. Braga, R. R. São-Clemente, C. Ferreira, Jodir P. Silva","doi":"10.1051/alr/2022010","DOIUrl":"https://doi.org/10.1051/alr/2022010","url":null,"abstract":"Age, growth and maturity of frigate tuna (Auxis thazard) were studied for the first time in Southeast Brazil. A total of 650 fish (265–494 mm Fork Length) were sampled from beach-seine landings between March 2018 and February 2019. Sectioned fin spines from 548 specimens were processed and age was determined by counting and measuring of increments. Growth parameters were fitted to length-at-age data using the von Bertalanffy growth function and were compared to the literature using the growth performance index (Phi). Macro and microscopic characterization of gonads and physiological indexes were used for the analysis of the reproductive cycle. The length distribution did not differ by sex. Assigned ages were between 0+ and 4 years, with annual increments formed during winter. Coefficient of variation between readings was 11%. Growth differed by sex, and the von Bertalanffy growth parameters were L∞ = 471 mm; k = 0.47 year−1; and t0 = –1.46 year−1 for females; L∞ = 498 mm; k = 0.35 year−1; and t0 = –2.01 year−1 for males. Phi was 5.0 for both sexes. Estimated growth rate is among the lowest recorded for the species, possibly related to the method used for age and growth assessment. Gonadosomatic index peaked in December, associated with the upwelling of the South Atlantic Central Waters, at a temperature of approximately 16 °C. Spawning activity in colder waters has never been reported for this species and may be influenced by a richer habitat caused by the intrusion of more nutritive rich waters during spring-summer, which allows larval development. Length-at-first-maturity (L50) was 345.4 mm for females and 329.8 mm for males.","PeriodicalId":55491,"journal":{"name":"Aquatic Living Resources","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57824634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Chizhayeva, A. Amangeldi, Y. Oleinikova, A. Alybaeva, A. Sadanov
Industrial aquaculture is a dynamic area capable of solving problems of healthy nutrition and food security. Increase of organic pollution, number of opportunistic microorganisms in the aquatic environment of fish farms and the global contamination of feed by mycotoxigenic fungi are serious problems of industrial fish cultivation. The results are weakening of the general condition of fish, immunosuppression, the occurrence of various diseases complicated by drug resistance, the accumulation of antibiotics and chemical compounds in tissues. Probiotics can be an alternative to antibiotics. The use of probiotics is also one of the biological methods for maintaining and restoring the normal physiological state of fish and increasing their productivity. The aim of this review is the scientific justification of the use of lactic acid bacteria as the safest microorganisms in the development of probiotics for aquaculture. The review presented provides criteria for selecting candidate strains for effective probiotics development. The advantages of lactic acid bacteria for the prevention or control of infectious diseases in cultured fish are considered. Lactic acid bacteria are representatives of the fish microbiota, they have antagonistic activity against opportunistic pathogens, fungi and viruses that cause microbiological spoilage of feed, pollute water bodies, and cause diseases of aquatic animals. The review provides information on various researches in which lactic acid bacteria or products derived from them have been used to assess their potential in aquaculture. Numerous scientific studies prove the value of this vast group of microorganisms for the prevention and treatment of fish diseases, for increasing the resistance of aquatic animals to infectious diseases and various stresses, for improving their survival and productivity, and for improving water sanitation in fish reservoirs. Increased use of effective probiotic lactic acid bacteria in aquaculture can make the fish sector safer, more productive and friendly to the environment and human well-being, and will contribute to the sustainable development of aquaculture.
{"title":"Lactic acid bacteria as probiotics in sustainable development of aquaculture","authors":"A. Chizhayeva, A. Amangeldi, Y. Oleinikova, A. Alybaeva, A. Sadanov","doi":"10.1051/alr/2022011","DOIUrl":"https://doi.org/10.1051/alr/2022011","url":null,"abstract":"Industrial aquaculture is a dynamic area capable of solving problems of healthy nutrition and food security. Increase of organic pollution, number of opportunistic microorganisms in the aquatic environment of fish farms and the global contamination of feed by mycotoxigenic fungi are serious problems of industrial fish cultivation. The results are weakening of the general condition of fish, immunosuppression, the occurrence of various diseases complicated by drug resistance, the accumulation of antibiotics and chemical compounds in tissues. Probiotics can be an alternative to antibiotics. The use of probiotics is also one of the biological methods for maintaining and restoring the normal physiological state of fish and increasing their productivity. The aim of this review is the scientific justification of the use of lactic acid bacteria as the safest microorganisms in the development of probiotics for aquaculture. The review presented provides criteria for selecting candidate strains for effective probiotics development. The advantages of lactic acid bacteria for the prevention or control of infectious diseases in cultured fish are considered. Lactic acid bacteria are representatives of the fish microbiota, they have antagonistic activity against opportunistic pathogens, fungi and viruses that cause microbiological spoilage of feed, pollute water bodies, and cause diseases of aquatic animals. The review provides information on various researches in which lactic acid bacteria or products derived from them have been used to assess their potential in aquaculture. Numerous scientific studies prove the value of this vast group of microorganisms for the prevention and treatment of fish diseases, for increasing the resistance of aquatic animals to infectious diseases and various stresses, for improving their survival and productivity, and for improving water sanitation in fish reservoirs. Increased use of effective probiotic lactic acid bacteria in aquaculture can make the fish sector safer, more productive and friendly to the environment and human well-being, and will contribute to the sustainable development of aquaculture.","PeriodicalId":55491,"journal":{"name":"Aquatic Living Resources","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57824644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Çi̇ftçi, O. Eroğlu, Ş. Firidin, Hacı Savaş, Yusuf Bektaş
In this study, the genetic relationships of 804 tarek (Alburnus tarichi) samples from a total of 18 populations, including the potamodromus and resident individuals from Lake Van basin in eastern Turkey, were studied by using nine microsatellite loci. A total of 93 alleles was detected, and the average number of alleles per locus was 10.3 ± 3.39. The mean estimated observed and expected heterozygosity were 0.340 ± 0.016 and 0.362 ± 0.015, respectively, which indicated a low level of polymorphism. After Bonferroni correction (P< 0.0027), the multi-locus test applied to each population revealed that 12 out of 18 populations were in Hardy-Weinberg equilibrium (HWE) (P = 0.0120–0.9981). Analysis of molecular variance (AMOVA) showed more than 76% genetic variability within individuals and 19% among populations, which was significantly higher than zero (FST = 0.19), and furthermore, a low level of genetic variation was observed among individuals within populations (4.84%: FIS = 0.06). Bayesian clustering analysis indicated that the total genetic variation grouped into 3 clusters. Additionally, the significance test results revealed that 11 of the 18 populations are threatened with extinction due to recent bottleneck events.We conclude that the tarek populations from the Lake Van basin can be classified into distinct genetic groups, based on microsatellite information. In addition, our results provide essential information for the development of a management plan that conserves the tarek's genetic diversity and achieves a sustainable fishery.
{"title":"Genetic diversity and population structure of Tarek (Alburnus tarichi), an endemic species to the Lake Van basin, Turkey","authors":"Y. Çi̇ftçi, O. Eroğlu, Ş. Firidin, Hacı Savaş, Yusuf Bektaş","doi":"10.1051/ALR/2021005","DOIUrl":"https://doi.org/10.1051/ALR/2021005","url":null,"abstract":"In this study, the genetic relationships of 804 tarek (Alburnus tarichi) samples from a total of 18 populations, including the potamodromus and resident individuals from Lake Van basin in eastern Turkey, were studied by using nine microsatellite loci. A total of 93 alleles was detected, and the average number of alleles per locus was 10.3 ± 3.39. The mean estimated observed and expected heterozygosity were 0.340 ± 0.016 and 0.362 ± 0.015, respectively, which indicated a low level of polymorphism. After Bonferroni correction (P< 0.0027), the multi-locus test applied to each population revealed that 12 out of 18 populations were in Hardy-Weinberg equilibrium (HWE) (P = 0.0120–0.9981). Analysis of molecular variance (AMOVA) showed more than 76% genetic variability within individuals and 19% among populations, which was significantly higher than zero (FST = 0.19), and furthermore, a low level of genetic variation was observed among individuals within populations (4.84%: FIS = 0.06). Bayesian clustering analysis indicated that the total genetic variation grouped into 3 clusters. Additionally, the significance test results revealed that 11 of the 18 populations are threatened with extinction due to recent bottleneck events.We conclude that the tarek populations from the Lake Van basin can be classified into distinct genetic groups, based on microsatellite information. In addition, our results provide essential information for the development of a management plan that conserves the tarek's genetic diversity and achieves a sustainable fishery.","PeriodicalId":55491,"journal":{"name":"Aquatic Living Resources","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57824343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alicia Mallet, J. Jouvenel, Morgane Broyon, N. Pirot, B. Geffroy
The mutable nassa, Tritia mutabilis, a marine gastropod that is widely exploited on the Adriatic coast is an important source of income for small-scale fishermen in the Mediterranean Sea, particularly in the Gulf of Lion. However, the lack of knowledge on the ecology and biology of this species limits our capacities to propose and produce an effective management plan. As a result, stocks are currently declining, especially in Italy. In order to optimize a management plan for this fishery, we designed a study to better characterize the reproductive biology of T. mutabilis, using gonad histology and performing a regular monitoring of population size frequency. The average shell height of individuals during the breeding period was 24 ± 2.7 mm for males and 30 ± 3.7 mm for females. The presence of small females (10 mm) and large males (32 mm) in the whole sample challenged previous assumptions regarding protandry (sex change from male to female). The size at first maturity was estimated for males and females at 17.5 mm and 24.4 mm shell height, respectively. In Italy, current management measures include a minimum conservation reference size of 20 mm in shell height. Therefore, it is likely that many individuals that did not reproduce are being caught, which could partly explain the decline observed, despite conservation measures introduced more than ten years ago. Overall, our study provides some baseline information to establish, in consultation with fishermen, management measures for this small-scale fishery in France.
{"title":"Histology of Tritia mutabilis gonads: using reproductive biology to support sustainable fishery management","authors":"Alicia Mallet, J. Jouvenel, Morgane Broyon, N. Pirot, B. Geffroy","doi":"10.1051/ALR/2021006","DOIUrl":"https://doi.org/10.1051/ALR/2021006","url":null,"abstract":"The mutable nassa, Tritia mutabilis, a marine gastropod that is widely exploited on the Adriatic coast is an important source of income for small-scale fishermen in the Mediterranean Sea, particularly in the Gulf of Lion. However, the lack of knowledge on the ecology and biology of this species limits our capacities to propose and produce an effective management plan. As a result, stocks are currently declining, especially in Italy. In order to optimize a management plan for this fishery, we designed a study to better characterize the reproductive biology of T. mutabilis, using gonad histology and performing a regular monitoring of population size frequency. The average shell height of individuals during the breeding period was 24 ± 2.7 mm for males and 30 ± 3.7 mm for females. The presence of small females (10 mm) and large males (32 mm) in the whole sample challenged previous assumptions regarding protandry (sex change from male to female). The size at first maturity was estimated for males and females at 17.5 mm and 24.4 mm shell height, respectively. In Italy, current management measures include a minimum conservation reference size of 20 mm in shell height. Therefore, it is likely that many individuals that did not reproduce are being caught, which could partly explain the decline observed, despite conservation measures introduced more than ten years ago. Overall, our study provides some baseline information to establish, in consultation with fishermen, management measures for this small-scale fishery in France.","PeriodicalId":55491,"journal":{"name":"Aquatic Living Resources","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57824000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Vandeputte, A. Bestin, Louarn Fauchet, J. Allamellou, S. Bosc, O. Menchi, P. Haffray
Parentage assignment with genomic markers provides an opportunity to monitor salmon restocking programs. Most of the time, it is used to study the fate of hatchery-born fish in those programs, as well as the genetic impacts of restocking. In such analyses, only fish that are assigned to their parents are considered. In the Garonne-Dordogne river basin in France, native salmon have disappeared, and supportive breeding is being used to try to reinstate a self-sustained population. It is therefore of primary importance to assess the numbers of wild-born returning salmon, which could appear as wrongly assigned or not assigned, depending on the power of the marker set and on the size of the mating plan. We used the genotypes at nine microsatellites of the 5800 hatchery broodstock which were used from 2008 to 2014, and of 884 upstream migrating fish collected from 2008 to 2016, to assess our ability to identify wild-born salmon. We simulated genotypes of hatchery fish and wild-born fish and assessed how they were identified by the parentage assignment software Accurassign. We showed that 98.7% of the fish assigned within the recorded mating plan could be considered hatchery fish, while 93.3% of the fish in other assignment categories (assigned out of the mating plan, assigned to several parent pairs, not assigned) could be considered wild-born. Using a Bayesian approach, we showed that 31.3% of the 457 upstream migrating fish sampled from 2014 to 2016 were wild-born. This approach is thus efficient to identify wild-born fish in a restoration program. It remains dependent on the quality of the recording of the mating plan, which we showed was rather good (<5% mistakes) in this program. To limit this potential dependence, an increase in the number of markers genotyped (17 instead of 9) is now being implemented.
{"title":"Can we identify wild-born salmon from parentage assignment data? A case study in the Garonne-Dordogne rivers salmon restoration programme in France","authors":"M. Vandeputte, A. Bestin, Louarn Fauchet, J. Allamellou, S. Bosc, O. Menchi, P. Haffray","doi":"10.1051/ALR/2021008","DOIUrl":"https://doi.org/10.1051/ALR/2021008","url":null,"abstract":"Parentage assignment with genomic markers provides an opportunity to monitor salmon restocking programs. Most of the time, it is used to study the fate of hatchery-born fish in those programs, as well as the genetic impacts of restocking. In such analyses, only fish that are assigned to their parents are considered. In the Garonne-Dordogne river basin in France, native salmon have disappeared, and supportive breeding is being used to try to reinstate a self-sustained population. It is therefore of primary importance to assess the numbers of wild-born returning salmon, which could appear as wrongly assigned or not assigned, depending on the power of the marker set and on the size of the mating plan. We used the genotypes at nine microsatellites of the 5800 hatchery broodstock which were used from 2008 to 2014, and of 884 upstream migrating fish collected from 2008 to 2016, to assess our ability to identify wild-born salmon. We simulated genotypes of hatchery fish and wild-born fish and assessed how they were identified by the parentage assignment software Accurassign. We showed that 98.7% of the fish assigned within the recorded mating plan could be considered hatchery fish, while 93.3% of the fish in other assignment categories (assigned out of the mating plan, assigned to several parent pairs, not assigned) could be considered wild-born. Using a Bayesian approach, we showed that 31.3% of the 457 upstream migrating fish sampled from 2014 to 2016 were wild-born. This approach is thus efficient to identify wild-born fish in a restoration program. It remains dependent on the quality of the recording of the mating plan, which we showed was rather good (<5% mistakes) in this program. To limit this potential dependence, an increase in the number of markers genotyped (17 instead of 9) is now being implemented.","PeriodicalId":55491,"journal":{"name":"Aquatic Living Resources","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57824098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：