Fig. 3

GnRH-R2 concentration in serum during the oocyte development stage in Coila nasus. The stages were defined as: onset stage (stage I; fish collected in March), developmental stage (stage II; April), multiplication stage (stage III; May), mature stage (stage IV; June), spawning stage (stage V; late June), spawned stage (stage VI; July), and rest stage (stage VII; August). Data were collected by enzyme-linked immunosorbent assays and are expressed as the mean ± SE (n = 3). Columns with different letters above them are significantly different (P < 0.05, a<b<c)