The use of statolith analyses and particle‐tracking experiments to reveal the migratory route of the swordtip squid (Uroteuthis edulis) caught on the Pacific side of Japan

Abstract

AbstractTo verify the hypothesis that swordtip squid (Uroteuthis edulis) harvested on the eastern and western sides of Japan originate from a single stock, which is transported from the East China Sea, the hatching ground and migratory route of squid collected from the eastern (Pacific) side of Japan were estimated using micro‐increment counts and the Sr:Ca ratios in statoliths as well as backward and forward particle‐tracking experiments. The results of both the empirical water temperatures estimated by the Sr:Ca ratios in the statoliths as well as the trajectories and ambient water temperatures of the particles in the experiments supported the hypothesis, suggesting that the sampled individuals experienced cold waters caused by upwelling, originating from the Kuroshio off northern Taiwan. It was found that the environmental settings in the particle‐tracking experiments of this study adequately represented the habitats of the squid and that the movement of this species is highly dependent on currents. This information is essential to establishing a stock management system for sustainable fishing.