Fig. 3. (A) Amount of glycoprotein 2 (GP2) mRNA, (B) follicle-stimulating hormone β (FSHβ) mRNA and (C) FSH in the pituitaries of chum salmon in the central Bering Sea and the NW Pacific Ocean, 2001–2003. Fish were divided into immature fish and maturing adult I and II on the basis of histological observation of the gonads. Value are means ± s.e.m. Significant differences among groups are indicated with different letters (P<0.05 one-way ANOVA and Tukey's test). See Table 1 for the number of fish.