Formulae to estimate standard body length for regional forms of the sea cucumber Apostichopus japonicus in Japan

Abstract

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=5082+2.02·(L·B) 1/2]. We also obtained the following two standardization equations: Hokkaido [Le=2021·(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.