Investigation And Resource Impact Analysis Of Fishing Catch Of Recreational Trawler In Zhoushan Sea Area

In order to analyze the influence of recreational trawler operation on juvenile fishery resources,main economic types,total amount and bottom fishery resources,preliminarily propose the suitable capacity of Zhoushan recreational trawler,discuss its consistency with current recreational fishery management policy and then provide more reference for competent authorities to formulate management policies of recreational trawlers,the project investigated the number and operation of recreational trawler in Zhoushan city.Three survey stations were set up in Shengsi,Daishan and Putuo of Zhoushan in July 2020,and eight survey stations were set up in Daishan of Zhoushan in May and October 2020,to conduct a survey of the catch of single-vessel wing-bag trawl.The survey results show that:in May,the total weight of the catch was 13.96 kg,and the total catch was 4454 ind.;the average catch weight per net was 1.75 kg/net and 557ind./net;the weight density was about 157.07kg/km~2and the mantissa density was about50.10×10~3ind./km~2;a total of 23 species were identified and the larva proportion of 9main economic species was 40.94%.In July,the total weight of the catch was 192.62 kg,and the total catch was 18479 ind.;the average catch weight per net was 21.40 kg/net and2053 ind./net;the weight density was about 3082 kg/km~2and the mantissa density was about 295.64×10~3ind./km~2;a total of 55 species were identified and the larva proportion of 11 main economic species was 75.6%.In October,the total weight of the catch was26.24 kg,and the total catch was 8317 ind.;the average catch weight per net was 3.28kg/net and 1040 ind./net;the weight density was about 236.12 kg/km~2and the mantissa density was about 74.85×10~3ind./km~2;a total of 36 species were identified and the larva proportion of 14 main economic species was 59.63%.The research results show that:when recreational trawlers were used to carry out experiential fishing activities,the proportion of larva in the catch was higher,and the larva of fishery resources of Zhoushan was damaged greatly during the summer season.The total catch of recreational trawlers in the off-fishing season was about 773.16×10~3kg,accounting for 4.11%of the instantaneous amount of fishery resources in Zhoushan coastal fisheries,which has little influence on the total amount of fishery resources.The capacity of recreational trawlers in Zhoushan sea area during the summer season fishing suspension was 245,which has basically reached the capacity during the summer season fishing suspension.The species of bottom and benthic resources accounted for 73.9%,70.9%and72.2%respectively in May,July and October 2020.So it had a great influence on the bottom and benthic fishery resources.In addition,among the catch of recreational trawlers,8 main economic species accounted for about 0.37%of the total annual fishing output in Zhoushan,and had little influence on the main economic species.Combined with the survey results and conclusions,it is suggested to cancel the"management requirement that the total weight of fish caught in a single voyage should not exceed 20kg",strictly control the trawling time of a single voyage and strengthen the publicity of conservation,carefully consider abolishing recreational trawling operations and explore further the minimum mesh size requirements of trawl or improve trawl fishing gear to protect larva resources.