Effect of parental origin on jumping and spacing behaviours of juvenile ayu Plecoglossus altivelis with special reference to their upstream migration.

概要

論文の詳細を見る
The spacing pattern and jumping activity were compared for 3 different stocks of juvenile ayu, reared under identical hatchery conditions for about 3 months after fertilization, which were the offspring of landlocked fish from Lake Biwa (LAKE), amphidromous type from the Kiso River (RIVER), and the 14th generation hatchery strain kept at Gunma prefecture (HR-G). LAKE dispersed widely in an experimental tank (95cm in diameter) during the daytime, while HR-G formed a tight aggregation and/or schooling with the mean diameter of 48cm. Jumping activity was the highest in LAKE (4.0 times per individual), followed by RIVER (3.3) and HR-G (3.0). These results suggest that parental origin, or genetic factor, controls the spacing and jumping behaviours of the ayu, and thus upstream migration of this species since these behaviours are known to have a close relationship with a tendency to migrate upstream.