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Chinese Journal of Applied Ecology ›› 2023, Vol. 34 ›› Issue (1): 242-248.doi: 10.13287/j.1001-9332.202301.037

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Optimum capture size of Trichiurus japonicus in the East China Sea

YUAN Fan1,2,3, ZHU Wen-bin1*, WANG Zhong-ming1, ZHU Kai1 , ZHOU Yong-dong1, XU Han-xiang2   

  1. 1Zhejiang Marine Fisheries Research Institute/Scientific Observing and Experimental Station of Fishery Resources for Key Fishing Grounds, Ministry of Agriculture and Rural Affairs/Key Laboratory of Sustainable Utilization of Technology Research for Fishery Resources of Zhejiang Province, Zhoushan 316021, Zhejiang, China;
    2Marine and Fishery Institute of Zhejiang Ocean University, Zhou-shan 316021, Zhejiang, China;
    3Zhejiang Society of Fisheries, Hangzhou 310023, China
  • Received:2022-01-04 Revised:2022-10-12 Online:2023-01-15 Published:2023-06-15

Abstract: Trichiurus japonicus is an economically valuable species in the East China Sea, whose allowable capture size varies with fishing effort in different years. To clarify the optimum capture size for T. japonicus in the East China Sea, we collected samples and data from T. japonicus targeting fishing gears such as trawls, canvas spreader stow nets and longlines from 2016 to 2020. We estimated growth and mortality parameters using the FiSAT II software, and calculated the size limit standards for capture. The results showed that the inflection point of anal length, the critical anal length and the anal length of one-year-old T. japonicus was 382.84, 397.12, and 216.05 mm, respectively. The anal length of maturity was 230.38 mm, and the minimum capture size (anal length) was 219.23 mm. Based on the yield per recruitment analysis using Beverton-Holt model, the current fishery reference points were under overfishing condition (tc=0.38 a, F=2.11), and the suggested optimum capture size was 364.64 mm. There would be a sharp decline of T. japonicus catches in the East China Sea if the suggested minimum capture size was substantially higher, which might be non-practical for local fishermen. Therefore, we suggested 220 mm as the capture size limit, which was close to the anal length of one-year-old fish and the anal length of maturity.

Key words: Trichiurus japonicus, growth and death parameter, Beverton-Holt model, optimum capture size.