Age-Structured Assessment Model for Georges Bank Winter Flounder.

摘要

An age-structured assessment model for Georges Bank winter flounder (Pseudopleuronectes americanus) stock during 1964-2000 is developed to provide an alternative to VPA-based analyses of stock status. Age-structured population dynamics of winter flounder are modeled using standard forward-projection methods for statistical catch-at-age analyses. Trends in the relative abundance of population biomass are measured by research survey indices for Georges Bank winter flounder. Three surveys were available: the NEFSC autumn groundfish survey (1963-2000), the NEFSC spring groundfish survey (1968-2000), and the Canadian spring groundfish survey (1987-2000). Two alternative models were examined in detail: (1) a model that used all three research survey time series (WINC, WINter flounder model including Canadian survey) and (2) a model that used the two NEFSC research survey time series (WIN, WINter flounder model). Both the WINC and WIN models provided similar trends in population biomass and fishing mortality, indicating that results were robust to the inclusion of the Canadian research survey time series. Based on model diagnostics, the WIN model that used the two NEFSC research survey time series provided the best fit to the data.