An integrated assessment model of seabird population dynamics: can individual heterogeneity in susceptibility to fishing explain abundance trends in Crozet wandering albatross?

• Published in: Journal of Applied Ecology
• Main Authors: Tuck, Geoffrey N., Thomson, Robin B., Barbraud, Christophe, Delord, Karine, Louzao, Maite, Herrera, Miguel, Weimerskirch, Henri
• Other Authors: Oceans and Atmosphere Flagship (CSIRO), CSIRO Oceans and Atmosphere Flagship, Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Indian Ocean Tuna Commission (IOTC)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: albatross; bycatch; conservation management; Crozet Island; evolution; heterogeneity; longline fishing; personality; population model; spatial management; [SDE]Environmental Sciences; Wandering Albatross
• Online Access: https://hal.science/hal-01304872; https://doi.org/10.1111/1365-2664.12462

International audience 1. Seabirds have been incidentally caught in distant-water longline fleets operating in theSouthern Ocean since at least the 1970s, and breeding numbers for some populations haveshown marked trends of decline and recovery concomitant with longline fishing effort withintheir distributions. However, lacking is an understanding of how forms of among-individualheterogeneity may interact with fisheries bycatch and influence population dynamics.2. We develop a model that uses comprehensive data on the spatial and temporal distributionsof fishing effort and seabird foraging to estimate temporal overlaps, fishery catchabilityand consequent bycatch. We apply a population model that is structured by age, sex, lifestage and spatially to Crozet Island wandering albatross and explore how heterogeneity insusceptibility to capture may have influenced the population’s demography over time.3. A model where some birds were assumed to be more susceptible to fisheries bycatch wasable to successfully replicate the observed trend in breeding pairs. Considerably poorer fitswere found without this assumption. Results suggested that the more susceptible birds mayhave been removed from the population by the 1990s.4. The model was also able to highlight areas, times and fleets prone to increased bycatch.Knowledge of these factors should assist fisheries and conservation management bodies toquantify and reduce seabird bycatch through spatial management and fleet-specific mitigationefforts.5. Synthesis and application. Many seabirds show complex life histories that make themhighly susceptible to additional incidental mortality from fishing vessels. By applying apopulation model that integrates key aspects of seabird and fishery dynamics, we were able toexplain the observed trends in the breeding population of Crozet wandering albatross andidentify key areas and fleets where further mitigation may be required. In addition, the potentialremoval of a category of birds that shows increased susceptibility to capture has ...