Morphometric Variation between the Swordtip (Photololigo Edulis) and Mitre (P. Chinensis) Squids in the Waters off Taiwan

Abstract

In this study, we analyzed the morphometric variation between Photololigo edulis and P. chinensis occurring in the waters around Taiwan by using univariate and multivariate morphometric methods. We measured 18 morphometric characters from 749 squid specimens, which were collected from the waters in three regions: off northeastern Taiwan, Penghu, and Hsinchu, respectively. Based on these data, the result from the univariate morphometric method showed that the morphometric characters of P. chinensis from Hsinchu were more different from those of P. chinensis from Penghu as well as those of P. edulis from northeastern Taiwan. However, through the stepwise discriminant analysis, a multivariate morphometric method, 13 morphometric characters were selected and discriminated the specimens among the three regions with a correct classification rate of discriminant functions of 84.65%. Also, the morphometric characters of specimens from the waters off Penghu and Hsinchu were more similar than those specimens from the waters off northeastern Taiwan.