Population structure, condition factor and relative growth of the grenadier Coelorinchus jordani (Gadiformes, Macrouridae) in Kagoshima Bay, southern Japan

Abstract

In order to examine the sex ratio, body size composition, condition factor and relative growth, a total of 1638 specimens of the grenadier Coelorinchus jordani (Gadiformes, Macrouridae) was collected from Kagoshima Bay, southern Japan, at 115-227 m in depth, using a commercial bottom trawler. Proportions of males and females were not significantly different in the shallow area (less than 200 m in depth), while in the deep area (above 200 m in depth), males had a significantly higher proportion than females. C. jordani had a sexual dimorphism in body size. The body size was significantly greater in the shallow area than the deep area for both sexes. Small individuals less than 20 mm in pre-anal length occurred only in the deep area. The condition factors of both males and females changed with seasonal oscillation. The symmetric relationship between pre-anal length and total length was represented by significantly different equations between sexes. The relationship between pre-anal length and body weight was described by a double-logarithmic linear equation without significant difference between sexes.