| Summary: | 碩士 === 國立臺灣海洋大學 === 環境生物與漁業科學學系 === 99 === The spook fish, Hydrolagus mitsukurii is a deep benthic chondrichthyan fish, and it distributes in the northeastern, eastern and southwestern waters off Taiwan. A total of 549 females (8.6-64.2 cm TL) and 505 males (9.6-59.4 cm TL) were collected in Daxi fish market, Yilan County between Nov. 2009 and Dec. 2010. All specimens were caught by commercial bottom trawlers in the eastern waters off Gueishan Island, under the depth of 400-600 m. Nnumber of convexes on the surface of the toothplate were used to estimate the age in this study. Because of wear of some toothplates, original convexes of imperfect toothplates were back-calculated based on data of complete toothplates. The maximum numbers of convexes were back-calculated to be 31 and 27 for female and male, respectively. The convex was formed biannually in March and September via edge analysis. The best growth function for females and males was Gompertz function. The growth parameters were L∞ = 72.15 cm, k = 0.164 yr-1 for females, and L∞ = 64.57 cm, k = 0.189 yr-1 for males. The maximum theoretical age of females and males was 21.7 yrs and 18.6 yrs, respectively.
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