Research Document 1998/42

Status of Atlantic salmon in Restigouche River in 1997

By A. Locke

Abstract

An angling-based assessment assuming 30-50% exploitation indicated that egg deposition and large salmon spawning escapement were about 35-65% of the conservation requirement for the Restigouche River. Visual counts estimate that large salmon escapement was approximately 40-50% of requirement and support the conclusion of the angling-based assessment that small salmon spawning escapement was in excess of the requirement. Ass indices of abundance indicated that returns to the river were low in 1997. Returns to counting fences on the Matapedia and Upsalquitch rivers were 36-38% below the five-year mean return of large salmon but only 5% (Upsalquitch River) below the mean of small salmon. Total returns of large salmon to the river did not exceed the conservation requirement.

Estimated returns by the angling catch-based method were 7,400-11,700 large and 7,900-13,200 small salmon. By a combination of the visual methods, returns were conservatively estimated at a minimum of 7,300 large and 6,000 small salmon. Angling catches (retained+released) were 2,649 large and 3,408 small salmon. Retained angling harvests were 729 large and 3,079 small salmon. New Brunswick First Nations harvest was at least 166 large and 26 small salmon. Québec First Nation harvest was unknown but was estimated as 985 large and 18 small salmon.

Based on a significant historical correlation of small salmon returns in year x to large salmon returns in year x+1 in the Matapedia River, and on the basis of average small salmon returns to the Restigouche River in 1997, there may be an expectation of average 2-sea-winter salmon returns in 1998. However, this expectation must be regarded with caution given the low returns of large salmon in the Restigouche system in 1997.

Densities of juvenile age classes, determined by electrofishing, were 7-29% above the five-year means.

Conservation requirements and stock assessments of the five major tributaries of the Restigouche system are presented here for the first time. According to visual surveys by divers, none of the stocks achieved egg deposition at the level of 2.4 eggs/m². Egg depositions of the Little Main Restigouche and Matapedia stocks were estimated at 84-86% of the conservation requirement. Kedgwick, Upsalquitch and Patapedia egg depositions were estimated at from a bit under half to about three quarters (43-73%) of the requirement. This estimate may be overly conservative for the Patapedia and Upsalquitch because of incomplete spatial coverage by the surveys in these rivers.

Large salmon returns in excess of spawning escapement requirements occurred only in the Matapedia River. Small salmon returns to all the tributaries were in excess of spawning escapement requirements.

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