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Chinese Journal of Applied Ecology ›› 2019, Vol. 30 ›› Issue (7): 2426-2436.doi: 10.13287/j.1001-9332.201907.015

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Probability distribution characteristics of stock density in offshore of northern South China Sea.

CAI Yan-cong, HUANG Zi-rong, XU You-wei, SUN Ming-shuai, XU Shan-nan, ZHANG Kui, CHEN Zuo-zhi*   

  1. South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences/Key Laboratory of Open-Sea Fishery Development, Ministry of Agriculture and Rural Affairs, Guangzhou 510300, China.
  • Received:2018-09-15 Online:2019-07-15 Published:2019-07-15
  • Contact: * E-mail: zzchen2000@163.com

Abstract: Based on catch data from the bottom trawl survey by eight cruises in offshore of northern South China Sea during 2014-2017, we analyzed the stock density distribution and explored its probability distribution with statistical method, which was further used to estimate the mean stock density in this region. The results showed that the coefficient of variation (CV) for stock density ranged from 0.67 to 1.03 for all the periods, indicating a highly uneven spatial distribution of stock density. The frequency distribution of fishery resource density was characterized by obvious right-skewed, which was dominated by stock density of 0-1000 kg·km-2. The results of one sample Kolmogorov-Smirnov test indicated that three probability distribution patterns were suitable for stock density in this region, including Lognormal, Gamma and Weibull distributions. In terms of the mean stock density estimation, the values from Lognormal showed no statistically significant difference from those from others, but the opposite result was obtained between Gamma and Weibull distributions. Compared with 1960s-1970s, the appropriate probability distribution pattern of stock density has changed from single to multiple types. Variation of the proportion of low catch resulted from the changes in the structure of fishery resources, fishing effort and climate change might cause the alte-ration of probability distribution.