Reduced oceanic growth of growth hormone pseudogene‐positive female masu salmon Oncorhynchus masou

This study compared the growth rates of female masu salmon Oncorhynchus masou, who possessed a male‐specific gene marker, the growth hormone pseudogene (GHp), and normal females, as estimated from their scale growth. There was a difference between the growth rates of GHp‐positive females and those of normal females of the same age during the ocean period, although their growth rates during the river period were similar. These results suggest that GHp‐positive salmonid females exhibit male‐like characteristics such as reduced feeding activity during the ocean period, which depresses their growth.