1Graduate School of Fisheries Science, Hokkaido University, Hakodate, Hokkaido 041-8611, 2Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, 3Faculty of Integrated Arts and Sciences, The University of Tokushima, Nanjomishima, Tokushima 770-8501, Japan
Regression equations to estimate the standard (i.e. anesthetized) body length Le (mm) of the Japanese sea cucumber Apostichopus japonicus (green type) from simultaneous measurements of body length L and breadth B were calculated for populations in several waters around Hokkaido, and compared with the regression in Seto Inland Sea [Le=2.32+2.02•(L•B)1/2] in mainland Japan. The following equations were proposed: Sea of Okhotsk [Le=2.26•(L•B)1/2]; Sea of Japan [Le=2.17•(L•B)1/2]; Funka Bay [Le=2.21•(L•B)1/2]; Tsugaru Strait [Le=2.27•(L•B)1/2] in Hokkaido; and Mutsu Bay in mainland Japan [Le=5.82+2.02•(L•B)1/2]. We also obtained the following two standardization equations: Hokkaido [Le=2.21•(L•B)1/2] and mainland Japan [Le=5.30+2.01•(L•B)1/2], suggesting the morphological difference of A. japonicus between these two areas.