한국 고등어(Scomber japonicus) 자원 평가를 위한 Stock Synthesis 소프트웨어의 체장 기반 모델 적용

Abstract

Stock Synthesis (SS) is one of the fishery stock assessment software packages designated as the standard package of the US NOAA Fisheries. SS started to be developed in 1983 by Methot, and is implemented in Auto-Differentiation Model Builder (ADMB), which is a numerical optimization software language for estimating multiple parameter in a non-linear model. Although SS has been applied in a wide variety of fish assessments, there is no case of applying SS to a fish stock assessment in Korea. The main objective of this study was to apply the size-structured model in SS for assessment of Korea chub mackerel (Scomber japonicus). In addition, I performed the model validation through a simulation study and retrospective error analysis. The data used in this study were body sizes from 2000-2019, and fishery total catch (MT), and catch-per-unit-effort (CPUE in MT/haul) from 1975-2019. To perform a retrospective error analysis, I considered two cases. Case 1 (C1) was assumed to use all available data, and Case 2 (C2) was assumed to use data from 2000 to 2019, the period when all data were simultaneously available. The results of estimates in two cases showed significant differences in the estimates of growth parameters and annual recruitment deviations. While the model appeared to fit the data better in C1 than in C2, the simulation study showed that the model was more stable in C2 in terms of numerical convergence than in C1. The model did not represent a retrospective pattern, and the Mohn's ρ values were also found to have negligible retrospective errors. The estimated annual stock spawning biomass in both cases showed a similar trend, and was found to increase gradually over time.