Stock assessment of winter-spawning cohort for Todarodes pacificus based on the sea surface temperature in the spawning ground

Abstract:

Todarodes pacificus is a commercially important oceanic cephalopod resource, and its resource changes are vulnerable to the impact of the marine environment. In this study, the intrinsic natural growth rate (r) and the maximum environmental capacity (K) of the fluctuation parameters of the Todarodes pacificus population were combined with the sea surface temperature (SST) to construct four surplus production models respectively, which evaluated the changes in Todarodes pacificus population resources under the influence of SST. The research results showed that the resource evaluation model (model 2, model 3, and model 4) with environmental factors added to the four surplus production models had a deviation information criterion (DIC) value smaller than that of the traditional residual production model (model 1). The DIC value of the model 4 was the smallest (132.6), indicating that the model had the highest accuracy. According to the best model assessment, the fishing mortality F_t of Todarodes pacificus from 2007 to 2018 was lower than F_MSY. When MSY was 41.28×10⁴t, B_MSY reached 49.66×10⁴t, and there was a phenomenon of resource-based overfishing, but resources were gradually recovering. Studies have shown that the resource status of the winter population of Todarodes pacificus is greatly affected by the environment, so it is necessary to seriously consider the impact of environmental factors such as SST in future resource development and scientific management.