Stock identification of sword prawn Parapenaeopsis hardwickii in the East China Sea and Taiwan Strait inferred by morphometric variation

Morphometric differences were used to elucidate the stock structure of sword prawn Parapenaeopsis hardwickii in the East China Sea and Taiwan Strait. Six samples were collected separately from the north of the East China Sea (NECS-02) and waters off Tamsui (Tamsui-10), Taichung (Taichung-11 and Taichung-02), Putai (Putai-02) and Cheding (Cheding-02). Eleven measurements made for each individual were size-standardized by allometric methods and the resulting measurements were analyzed by cluster analysis and canonical variate analysis (CVA). Randomization tests were used to test the morphometric variation between groups derived from cluster analysis and CVA. The results of cluster analysis and CVA indicated that the six samples were clustered into three groups: the first group included the NECS-02 sample; the second included the Tamsui-10 and Taichung-11 samples; and the third included the Taichung-02, Putai-02 and Cheding-02 samples. Randomization tests showed that morphometric differences among the three groups were significant. Animals with the same morphometric measurements are often assumed to constitute a stock, so there appear to be at least three morphologically distinguishable stocks of this species in the East China Sea and Taiwan Strait. The first stock is in the north of the East China Sea, the second is in the waters adjacent to Tamsui and Taichung, and the third is in the waters adjacent to Cheding, Putai and Taichung.