Recent changes in the population of juvenile Atlantic salmon in the Matamek River, Quebec, Canada¹

Abstract

Investigations have been conducted on Atlantic salmon in the Matamek River since 1967. Numbers of juveniles have decreased in recent years and their growth has increased. Two year old smolt were not found in 1967, but in 1976 made up 20% of the run. The majority continue to migrate at three years old. The ratio of male to female smolt in 1967 was about 1:1, but in 1976 was about 1:3. The proportion of precocious male parr appears to have increased. The habitat has remained unchanged, and the fish are unexploited except for controlled scientific sampling. The changes are probably due to a reduced egg deposition. The ratio of two-sea-year salmon: grilse has decreased from 1:1·1 to 1:4·5 and the number of two-sea-year salmon appears to have decreased.

Author notes

¹ Contribution number 4002 from the Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA. Contribution number 31 from the Matamek Research Station, Quebec, Canada.