New size measurement for the Japanese sea cucumber Apostichopus japonicus (Stichopodidae) estimated from the body length and body breadth

Abstract

Anesthetized body length (La), an accurate measurement of body size of Japanese sea cucumber Apostichopus japonicus, is measured by using /-methol anesthetizer but it is difficult to apply La in the field. An estimation method of La from only one simultaneous measurement of body length (L) and body breadth (B), regardless of the degree of contraction or extension of the body, is proposed. In simultaneous measurement of L and B for each of 150 animals of both the green and the black types of A. japonicus, there were significant negative correlations between L and B in all animals. Further, √(LxB) was approximately constant regardless of the animals’ body form (coefficient of variance: 0.01–0.06). Thus, the regression equations for Le, estimated La, were calculated: the green type, Le=2.32+2.02×√(L·B); and the black type, Le=1.34+2.12×√(L·B). The error values between Le from these equations and La were small. The variances of Le were approximately one-quarter of those of L and half of B. From these, the equations can be used for body size measurements taken in the field.