The ecological and genetic impacts of escaped farmed salmon on wild salmon with recommended management measures for southern Newfoundland

Rideout, Keith M. (2006) The ecological and genetic impacts of escaped farmed salmon on wild salmon with recommended management measures for southern Newfoundland. Masters thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (5MB)

Abstract

Salmonid farming is a new and exciting industry for the rural areas of Newfoundland and Labrador; particularly those on the south coast of the Island in Bay d'Espoir and Fortune Bay. As with any industrial activity there are environmental impacts. In salmonid aquaculture these can include impacts related to farm effluents, disease amplification and transfer to wild stocks, and impacts associated with escapees from freshwater and marine farms. This paper attempts to highlight the degree of the escapement problem, particularly in those instances where the escaping species are free to interact and mate with wild conspecifics. This is the case in southern Newfoundland where domesticated Atlantic salmon (Salmo salar) are farmed in areas with natural Atlantic salmon runs. The impacts of farmed escapees will depend upon the degree of difference from wild salmon and on the ability of farmed escapees to perform (i.e., survive, grow, reproduce) in the wild. When farmed salmon are able to escape and survive in the wild, their impacts on wild salmon can be loosely separated into ecological, genetic and those related to disease transfer. This paper concentrates on ecological and genetic impacts with less emphasis on disease transfer issues. This approach was taken to limit discussion of escapee impacts to those possible after farmed salmon escape. Disease transfer from farmed fish, it is suggested, is as likely to occur from intact cages of fish as it is from escaped individual fish. Suitable farm siting and appropriate farm practice, particularly as it relates to containment issues, are the best ways to minimize the impact that farmed escapees can have on wild salmon stocks. To this end, Newfoundland and Labrador does consider wild salmon populations in its site licensing process, prior to farm establishment, and has developed one of the more elaborate and stringent Codes of Containment of any jurisdiction in the North Atlantic. There is still work to be done, however; programs to externally mark farmed Atlantic salmon, so that they can be differentiated from wild Atlantics, and to remove farmed Atlantic salmon from 'valuable' rivers prior to ascension, are needed.

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