Several studies have shown that animals (including birds) can exhibit different personality traits that have a strong influence on the survival of an individual and have consequent affects on population abundance. For harvested populations, given heterogeneity in behaviour within wild populations, some individuals may be more susceptible to bycatch and more likely to be removed from the populations.

Here we describe an age, sex, life-stage and spatially structured population model applied to the Crozet wandering albatross population. The model includes comprehensive data on the spatial and temporal distributions of fishing effort and foraging distributions to estimate temporal overlaps, fishery catchability and consequent bycatch. Results show that the model was not able to replicate the observed data without making broad assumptions about seabird catchability from the pelagic longline fleets and seabird behaviour. Namely, the rapid decline in breeding pairs observed between the late 1960s and the early 1970s could not be explained without assuming a heterogeneous population in which some birds were behaviourally more susceptible to fisheries bycatch than others.

This paper is the first to attempt to explain major changes in population size through differential fishing impacts on specific population phenotypes, and highlights the need for greater consideration of the ecological and management consequences of selective harvesting of susceptible behaviour types for seabirds, and other bycatch species.