Fig. 4. (A) Amount of luteinizing hormone β (LHβ) mRNA and (B) LH 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, as shown in the inset in Fig. 3. Values are means ± s.e.m. Significant differences among groups are identified with different letters (P<0.05 one-way ANOVA and Tukey's test). See Table 1 for the number of fish.