Original Research ARTICLE
Yield-per-recruit, utility-per-recruit and relative biomass of 21 exploited fish species in China’s coastal seas
- 1Fisheries College, Ocean University of China, China
- 2Institute for the Oceans and Fisheries, University of British Columbia, Canada
Based on growth and related fishery parameters, three approaches, yield-per-recruit(Y/R), utility-per-recruit (U/R) analyses and relative biomass (B/B0) analyses were applied to 21 economically important, trawl-caught species in China’s coastal seas to estimate their relative yield, economic value and biomass under different schedules of fishing mortality and mean length at first capture. The results show that all species suffer from overfishing, given the high average fishing mortality (F~1 year-1) and small mesh size (~1 cm) used by trawlers. Long-term Y/R would double and U/R (expressed as price per landed weight) would increase 5-fold if mesh size were increased to about 10 cm. Comparing Y/R and U/R showed that the benefits of higher prices for larger individuals were detectable only if larger mesh sizes are used, so that individuals are caught only after they have been able to grow. The Y/R analyses also allowed estimating the biomass of the 21 assessed populations relative to their unexploited biomass, i.e., B/B0. Species-specific B/B0 values ranged from 0.01 to 0.58, with a mean of 0.16 (+/- 0.03), i.e., much lower than the 50% reduction corresponding to Maximum Sustainable Yield (i.e., B/BMSY =1), or B/B0 =0.5). This confirms the many authors who reported systematic overfishing along China’s coastlines, and suggests that rebuilding stocks should be the foremost goal of fisheries management in China.
Keywords: Data-poor fisheries, Chinese coastal fisheries, yield per recuit, Utility per recruit, Biomass estimation, Stock assessments
Received: 09 Aug 2019;
Accepted: 08 Nov 2019.
Copyright: © 2019 Zhai and Pauly. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Miss. Lu Zhai, Fisheries College, Ocean University of China, Qingdao, China, firstname.lastname@example.org