{"title":"Improving the size selectivity of crayfish fyke-net codend, applying the hexagonal mesh and sorting grid","authors":"Mehmet Cilbiz, Celalettin Aydın","doi":"10.1071/mf23224","DOIUrl":null,"url":null,"abstract":"Context Owing to the use of fyke-nets with poor size selectivity in crayfish fishery, 40.7% of the landed undersized catch is discarded as bycatch. Aims This study investigated the effects of using hexagonal mesh (Hex34) instead of diamond nets (Com34) in the traditional crayfish fyke-net and the application of a sorting-grid (SG20, SG25, SG30) and stiff-rigged net (SRN34, SRN42, SRN50) on size selectivity. Methods A covered codend technique was used for determining the size selectivity of codends. Key results The average length at 50% retention probability (L50, in total length) for the trial groups of Com34, Hex34, SG20, SG25, SG30, SRN34, SRN42 and SRN50 was estimated as 9.1, 9.5, 10.1, 11.0, 12.3, 10.0, 10.3 and 11.1 cm respectively. Additionally, the discard rates were computed in the same order as 37.0, 27.3, 14.9, 5.8, 1.9, 19.1, 9.4 and 7.7%. Conclusions In conclusion, commercial crayfish (Com34) fyke-nets have a significantly high discard rate. In the modifications tested, the discard rate has been reduced to as low as 1.9%. When taking into account both L50 and fishing efficiency indicators, SRN42 was determined as the most successful trial group. Implications The application of the study results will make a significant contribution to the sustainability of natural crayfish stocks of Türkiye.","PeriodicalId":18209,"journal":{"name":"Marine and Freshwater Research","volume":null,"pages":null},"PeriodicalIF":1.8000,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Marine and Freshwater Research","FirstCategoryId":"93","ListUrlMain":"https://doi.org/10.1071/mf23224","RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"FISHERIES","Score":null,"Total":0}
引用次数: 0
Abstract
Context Owing to the use of fyke-nets with poor size selectivity in crayfish fishery, 40.7% of the landed undersized catch is discarded as bycatch. Aims This study investigated the effects of using hexagonal mesh (Hex34) instead of diamond nets (Com34) in the traditional crayfish fyke-net and the application of a sorting-grid (SG20, SG25, SG30) and stiff-rigged net (SRN34, SRN42, SRN50) on size selectivity. Methods A covered codend technique was used for determining the size selectivity of codends. Key results The average length at 50% retention probability (L50, in total length) for the trial groups of Com34, Hex34, SG20, SG25, SG30, SRN34, SRN42 and SRN50 was estimated as 9.1, 9.5, 10.1, 11.0, 12.3, 10.0, 10.3 and 11.1 cm respectively. Additionally, the discard rates were computed in the same order as 37.0, 27.3, 14.9, 5.8, 1.9, 19.1, 9.4 and 7.7%. Conclusions In conclusion, commercial crayfish (Com34) fyke-nets have a significantly high discard rate. In the modifications tested, the discard rate has been reduced to as low as 1.9%. When taking into account both L50 and fishing efficiency indicators, SRN42 was determined as the most successful trial group. Implications The application of the study results will make a significant contribution to the sustainability of natural crayfish stocks of Türkiye.
期刊介绍:
Marine and Freshwater Research is an international and interdisciplinary journal publishing contributions on all aquatic environments. The journal’s content addresses broad conceptual questions and investigations about the ecology and management of aquatic environments. Environments range from groundwaters, wetlands and streams to estuaries, rocky shores, reefs and the open ocean. Subject areas include, but are not limited to: aquatic ecosystem processes, such as nutrient cycling; biology; ecology; biogeochemistry; biogeography and phylogeography; hydrology; limnology; oceanography; toxicology; conservation and management; and ecosystem services. Contributions that are interdisciplinary and of wide interest and consider the social-ecological and institutional issues associated with managing marine and freshwater ecosystems are welcomed.
Marine and Freshwater Research is a valuable resource for researchers in industry and academia, resource managers, environmental consultants, students and amateurs who are interested in any aspect of the aquatic sciences.
Marine and Freshwater Research is published with the endorsement of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian Academy of Science.