Progress report on the preliminary analysis for sandlance population off Sanriku region with consideration of predation effects
Megumi Kawano, Tsutomu Tamura and Toshihide Kitakado
This is a short progress report on preliminary analysis for sandlance population off Sanriku region. A state-space two-stage population dynamics model with a stock-recruitment relationship was used for expressing the sandlance population dynamics. Catch and several abundance indices of sandlances and estimates of consumption of sandlances by some predators are used when estimating parameters in the population model. To take into account several stochastic flexibilities such as process errors, a Bayesian method was used to estimate the parameters and latent variables in the model. The results showed that the predation by the common minke whales accounts for little proportion of the current biomass of the sandlance population while predation impacts by other species might be dominant recently. The results are still preliminary because of needs for further validation of consumption of sandlances by predator species and further modelling process for linking sandlance and several predators through simultaneous estimation of populations dynamics.