Research Document - 2006/071

Conservation Requirements for Atlantic salmon (Salmo salar L.) in Labrador rivers

By Reddin, D.G., J.B. Dempson, and P.G. Amiro

Abstract

This paper provides interim methods and results for setting conservation requirements for Atlantic salmon (Salmo salar L.) in Labrador. The current standard conservation requirement of 240 eggs per 100 m² of parr-rearing habitat used for some Eastern Canadian rivers was deemed questionable for Labrador because Labrador rivers are on the northern edge of the range of Atlantic salmon and have a much colder climate. As a result of the colder climate, Labrador salmon generally spend longer in freshwater than do salmon populations to the south. Also, many Labrador rivers have abundant anadromous charr (Salvelinus alpinus L.) and trout (Salvelinus fontinalis Mitchill) which are not present in rivers to the south and may compete with salmon in freshwater for space and food. Because Labrador salmon are exploited in FSC (fisheries by aboriginal people for food, social and ceremonial purposes) fisheries in addition to angling, it requires the development of an interim value until such time that more definitive reference points can be developed. The preferred approach to defining biological reference points is through the analysis of stock and recruit relationships (SR). The collection of a sufficient SR time series requires a number of years of measured spawners and adult returns which do not exist for any Labrador river. We examined three previously published methods for deriving conservation limits and describe three alternate approaches for Labrador. The first of these alternate approaches is based on a quasi-stock and recruit method and uses fishery generated SR data. The second considers measured smolt production from Sand Hill River adjusted to variable freshwater survival rates. The third converts angling catch rates and river returns from a counting fence to construct SR data from a limit of 50% of the equilibrium population. Results from the three methods show 161 (95^th CL 110 to 309) eggs per 100 m² for the quasi-SR approach and 152 (95^th CL 80 to 370) eggs per 100 m² based on the Sand Hill smolt production data and 187 (95^th CL 153 to 201) from the SR analysis of Sand Hill River fence and angling data. Based on the data and analysis and until more information can be collected at higher escapements, it is recommended that a management target of 240 eggs per 100 m² and a conservation limit of 190 eggs per 100 m² be adopted.

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