Stock assessment of goldeyes rockfish, Sebastes thompsoni in Ulleungdo area

Abstract

This study estimated the characteristics of age growth and population ecological parameters of goldeyes rockfish, Sebasetes thompsoni in Ulleungdo area by using 731 samples from February 2013 to February 2014. The lowest value of the marginal index was witnessed in June once a year. The spawning period was estimated as April. Therefore, the duration from fertilization to the complete formation of the annual growth ring was fourteen months. Using the weighted average length of annual ring, the growth of Sebastes thompsoni was demonstrated by the von Bertalanffy growth equation as L_t=32.40(1-e^(-0.2442(t+0.6725) )) for combined sex. The instantaneous coefficient of total mortality (Z) was 0.78/year and the survival rate (S) was estimated 0.459 by Pauly method. The instantaneous coefficient of natural mortality (M) was estimated by Zhang and Megrey model (2006) to be 0.461/year. Based on the estimates of Z and M, the instantaneous coefficient of fishing mortality (F) was calculated to be 0.318/year (F = Z – M). In addition, the age at first capture (tc) was estimated to be 4.41 years. And current YPR was estimated 30.83g. Fmax and F0.1 were estimated 3.257/year and 0.673/year, respectively. YPR at Fmax and F0.1 were 53.36g, 41.7g, respectively. F35% and F40% were estimated 0.619/year, 0.509/year and 60.32g and 68.88g by SBPR, respectively. SBPR at Fcurrent was estimated 86.45g. FOTY was estimated 0.509/year. Current SBPR/SBPRMSY and F/FOTY were estimated 1.313, 0.629 respectively. And F/FOTY was estimated 0.629.