DOI: 10.5061/dryad.7f63m
title: Data from: An integrated assessment model of seabird population dynamics: can individual heterogeneity in susceptibility to fishing explain abundance trends in Crozet wandering albatross?

description: 1. Seabirds have been incidentally caught in distant-water longline fleets
 operating in the Southern Ocean since at least the 1970s, and breeding
 numbers for some populations have shown marked trends of decline and
 recovery concomitant with longline fishing effort within their
 distributions. However, lacking is an understanding of how forms of
 among-individual heterogeneity may interact with fisheries bycatch and
 influence population dynamics. 2. We develop a model that uses
 comprehensive data on the spatial and temporal distributions of fishing
 effort and seabird foraging to estimate temporal overlaps, fishery
 catchability and consequent bycatch. We apply a population model that is
 structured by age, sex, life stage and spatially to Crozet Island
 wandering albatross and explore how heterogeneity in susceptibility 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 was able to successfully replicate the observed trend in breeding
 pairs. Considerably poorer fits were found without this assumption.
 Results suggested that the more susceptible birds may have 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 to
 quantify and reduce seabird bycatch through spatial management and
 fleet-specific mitigation efforts. 5. Synthesis and application. Many
 seabirds show complex life histories that make them highly susceptible to
 additional incidental mortality from fishing vessels. By applying a
 population model that integrates key aspects of seabird and fishery
 dynamics, we were able to explain the observed trends in the breeding
 population of Crozet wandering albatross and identify key areas and fleets
 where further mitigation may be required. In addition, the potential
 removal of a category of birds that shows increased susceptibility to
 capture has important implications for the conservation management of this
 population and other iconic species incidentally caught by large-scale
 commercial fisheries.
description: Input data
 usedThis file lists the
 fishing effort data used in the modelData
 used.txtIOTC pelagic
 longlineIndian Ocean longline
 data from the IOTC (www.iotc.org)IOTC
 data.xlsxICCAT pelagic
 longlineAtlantic Ocean longline
 data from ICCAT (www.iccat.int/en/)ICCAT_all_v1_CSV.rarFalklands demersal longlineFalklands demersal longlineFalklands demersal LL.xlsxArgentina demersal longlineArgentina demersal longline (modelled)Arg_Dem_LL.xlsxChile demersal longlineChilean demersal and pelagic (Swordfish) longline (modelled)Chile_LL.xlsxSouth Africa demersal longline (kingklip)South Africa demersal kingklip (modelled)Saf_KKlip_Dem.txtNamibian demersal longlineNamibian demersal longline (modelled)Namibia Dem Hks Est.txt