Equilibrium analyses of the recovery feasibility of four Atlantic salmon (Salmo salar) populations in Nova Scotia and Southwest New Brunswick

No abstracts are to be cited without prior reference to the author.

Abundances of Atlantic salmon in rivers along the Atlantic Coast of Nova Scotia and around the Bay of Fundy, Canada, have declined precipitously during the last two decades. Equilibrium analyses were carried out on four populations in this region in order to evaluate the relationship between threats to these populations, their recovery potential, and the expected population response to recovery actions. Equilibrium models split the life cycle of a species into two or more parts and determine the population size at which the rates in each part of the life cycle are balanced such that the population does not increase or decrease in size. By varying the life history parameters in a way that represents the expected response to a human activity and examining the resulting change in equilibrium population size, the effects of the activity on the population can be evaluated. This approach places the expected population response to alleviating a threat in the context of other threats to the population. The threats and stressors discussed in each case study are representative of those affecting salmon population viability in Bay of Fundy and Nova Scotia Atlantic Coast Rivers: acidification, hydroelectric development, low freshwater habitat productivity, and low at-sea survival. The case studies illustrate the need for population-specific information for recovery planning and show that where multiple threats exist to a population, multiple actions are likely required to bring about recovery of that population.