Juvenile Salmon in the Estuary and Lower Nabisipi River and Some Results of Tagging

Abstract

Morphometric and hydrographic conditions indicated Nabisipi River, Quebec, has a fjord-type estuary with warm surface water of low salinity flowing out over cold saline water from the Gulf of St. Lawrence at all phases of the tidal cycle. The age, weight, and condition factors of 231 juvenile salmon from the estuary and 200 from the lower reaches of the river are given. Ages ranged from 1+ to 4+, condition factors (100 × weight in grams divided by the length in centimeters cubed) were slightly below 1.0 in the river and slightly higher in the estuary. Amphipods and capelin eggs were important constituents in the diet in the estuary, Corixidae in the river. Tagging indicated a growth rate of about 0.8 mm/day in the estuary. Both tagging and the handling of marked fish retarded growth. Tagging retarded growth for approximately 20 days. Tagging returns indicated a population of between 700 and 2500 fish near the mouth of the estuary in June and July 1961. These were thought to be remnants of the spring smolt run. In addition there was a small resident population of salmon parr living in the estuary. Numbers of fish in the estuary changed considerably from year to year.