Changes in Seal Habitat Use of Nearshore Waters around Newfoundland and Southern Labrador: Implications for Potential Predation on Salmon

ABSTRACT

The reasons for the decline in some Atlantic salmon (Salmo salar) stocks in Newfoundland and southern Labrador are not fully understood, but many resource users consider predation by seals in rivers and nearshore waters to be a contributing factor. To address these concerns, local ecological knowledge (LEK) interviews with resource users (n = 57) were conducted at 29 rivers throughout the Province to evaluate the potential for seal predation over a 25-year period when major changes were occurring in the structure of the Northwest Atlantic ecosystem. Based on LEK, eight rivers frequented by harp seals (Pagophilus groenlandicus), nine by harbor seals (Phoca vitulina) and three by gray seals (Halichoerus grypus) were evaluated as having a high potential for predation. According to respondents, the relative abundance of seals at these rivers started increasing in the mid 1990s or 2000, depending on the seal species involved. Variation in potential predation from river to river was attributed to a number of factors including the distribution of forage fish, variability in local ice conditions, the geography of the river and ecology of seal species frequenting the area. Resource users provided a useful and, in many cases, new perspective on the spatial and temporal overlap of seals, particularly harp seals, capelin (Mallotus villosus) and salmon in some areas. However, quantitative seal diet information and knowledge of seal-salmon relative abundances are required to assess the biological significance of these results from a salmon conservation perspective.

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