Retinal responses of pink salmon associated with its downstream migration.

摘要: THE seaward migration of juvenile Pacific salmon is usually nocturnal and confined to a relatively brief portion the night1. It has been suggested that “as light intensity falls rheotactic responses, which are large degree dependent on vision, fail, these fish pass down stream in shoals. The fact such mass movements occur during rather precise period night probably due dark adaptation eye blindness”2. In support this view, recent histophysiological examination retinae from several species Oncorhynchus shown an incompletely dark-adapted condition at time most active downstream migration3,4. As further test hypothesis, killed different intensities evening early morning have compared with were completely adapted same laboratory. pink fry (Oncorhynchus gorbuscha), specialized migrant salmon1, was selected for study.