Estimation of marine exploitation rates on Atlantic salmon (Salmo salar L.) stocks in Newfoundland, Canada

Abstract

Marine exploitation rates were estimated for nine Newfoundland Atlantic salmon (Salmo salar L.) populations, separately for small and large salmon size components. Estimates were derived using counts of salmon returning to fish counting facilities rather than from tagging studies and thus adjustments were not required to account for tag loss, handling or tagging mortality, or tag reporting rates. For all stocks combined, the overall marine exploitation rate during the period 1984-1991 averaged 45.3% (29.6-57.1%) on small salmon and 74.2% (57.7-83.7%) on large salmon. These estimates are considered minimum values. Concerns related to declining salmon abundance resulted in the closure of the Newfoundland commercial salmon fishery in 1992. Results are discussed in relation to previous estimates derived from tagging, and highlight the importance of accounting for marine exploitation when examining trends in salmon survival and return data even when commercial fisheries have been closed.