Biological characteristics including population structure, body length, body weight, growth and death of mullet Lizahaematocheila stocks were surveyed in 1135 samples collected from 18 sites in Liaohe Estuary in August and October 2014 and February and May 2015 by trawl and traps to reasonably protect and exploit the resources of mullet.The results showed that the mullet had average body length of 193.8 mm，with predominant body length of 180-190 mm, and the average body weight of 103.7 g，with dominant body weight of 80-100 g, indicating that juveniles and recruit population were the main catch targets.The relationship between body length and body weight was expressed as W=2×10-5L2.9545(R2=0.9161, n=1135), with growth parameters estimated by ELEFAN of L∞=404.3 mm, k=0.31 and t0=-0.44 a, respectively, and flexion age of 1.81 years old.Compared with the data of mullet in Bohai Sea，value of L∞ was declined from 620.0 mm to the current 404.3 mm，flexion age from 3-4 a to 1.83 a，showing miniaturization and lower age.The total mortality estimated by length-converted catch curve was found to be Z=2.20.The natural mortality calculated with Pauly’s empirical equation was M=0.42, and conversion the coefficient of fishing death was F=1.78, with exploit rate E=0.809 in recent years, indicating that mullet stocks were in overexploited.Under the current resource status in Liaohe Estuary, comprehensive consideration flexion age, growth, death and economic benefit and other specific factors, assessment with Beverton-Holt model, it is suggested that the legal age should be 1.81 a at its first capture, with the responding body length of 203 mm.
YE Jinqing, LIU Guize, YUAN Xiutang, YANG Qing.
Exploitation and protection of mullet Liza haematocheila stocks in Liaohe Estuary based on biological characteristics[J]. Journal of Dalian Fisheries University, 2020, 35(2): 302-307 https://doi.org/10.16535/j.cnki.dlhyxb.2019-062
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