Growth, mortality and reasonable utilization of Sebastes schlegelii in the artificial reef area of Weihai, Shandong Province

The artificial reefs are an important part of the marine ranching. Sebastes schlegelii which occurs in the coastal waters of China, including Yellow Sea and East China Sea, is a delicious seafood and has great economic value. We studied the resource status of S. schlegelii in different reef areas, such as growth, mortality and utilization of resources assessment, based on the cage questionnaire data in Weihai artificial reef area, Shandong province, from 2016 to 2018, by the means of ELEFAN Ⅰ, length-converted catch curve, Y_w/R curve and the biologic reference points. And uncertainty was incorporated into the estimation of the biological reference points F_0.1 and F_max by Monte Carlo simulation. The results of the first study on the resources of reef areas at different depths showed that the average body length, average weight, asymptotic body length and asymptotic weight of the S. schlegelii in shallow water areas were greater than those in the middle waters, and the deep water areas were the smallest, indicating that the artificial reefs in shallow water areas were more conducive to the protection of fishery resources. The fishing mortality coefficient and the natural mortality coefficient in the middle water area were greater than the deep water area, the shallow water area was the smallest. It is the first time to apply biological reference points F_0.1, F_max and uncertainty analysis to the resource assessment of different depths of reef area. The result showed that the judgment results of F_BRP at the three uncertainty levels were consistent with the none uncertainty, but the value of F_max was far greater than F_0.1, making it more difficult to judge the amount of reef resources as overexploitation. Therefore F_0.1 is more suitable for the evaluation of S. schlegelii. In combination with Gulland’s theory, biological reference points and yield per recruitment, reef resources were under the mild exploitation, and fishing intensity can be appropriately enhanced to increase catch yield. Shallow waters can be increased to F=0.39, and Y_w/R=25.60, corresponding fishing age is 1.83 a. The middle water area can be increased to F=0.46,Y_w/R=23.89 and fishing age 0.93 a, respectively. Deep water area can be increased to F=0.42, and Y_w/R=16.74 corresponding to a fishing age of 1.12 a.