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Illegal fishing bycatch overshadows climate as a driver of albatross population decline


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Michael, PE, Thomson, R, Barbraud, C, Delord, K, De Grissac, S, Hobday, AJ, Strutton, PG ORCID: 0000-0002-2395-9471, Tuck, GN, Weimerskirch, H and Wilcox, C 2017 , 'Illegal fishing bycatch overshadows climate as a driver of albatross population decline' , Marine Ecology Progress Series, vol. 579 , pp. 185-199 , doi: 10.3354/meps12248.

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Effective management of albatross populations requires understanding the impacts of environmental factors on albatross demographics. An integrated modelling approach incorporating multiple data sources can further the understanding of albatross demographics by incorporating error from all components of modeling, and help distinguish between variability related to one factor (e.g. environment) from that of another factor (e.g. density dependence). We applied such an integrated, spatially-explicit population model to quantify the impact of environmental conditions (sea surface temperature, SST), fisheries, and density dependence on a black-browed albatross Thalassarche melanophris population breeding on Kerguelen Island, southern Indian Ocean for the period 1950 to 2011. The model was structured by sex, age-class, and breeding stage, with a 5° × 5° spatial scale and monthly temporal scale. All parameters were estimated within a maximum likelihood framework. This includes estimation of seabird bycatch rates of each of 5 fishing super-fleets, grouped by gear type and reported bycatch rates: (1) Japanese pelagic longline, (2) other pelagic longline, (3) legal demersal longline, (4) trawl, and (5) illegal, unreported, and unregulated (IUU) demersal longline. A decline in the Kerguelen black-browed albatross population occurred between the mid-1990s through the mid-2000s. Our analysis attributes the majority of modelled bycatch to the IUU demersal longline super-fleet operating near Kerguelen Island for this period. Including SST during the incubation period indicated that warm SST favors high breeding success. These results indicate that effective management requires an integrated understanding of the impacts of the environment as well as illegal and legal fishing activities on vulnerable populations.

Item Type: Article
Authors/Creators:Michael, PE and Thomson, R and Barbraud, C and Delord, K and De Grissac, S and Hobday, AJ and Strutton, PG and Tuck, GN and Weimerskirch, H and Wilcox, C
Keywords: climate change, bycatch, demographics, integrated population model, albatross, Kergulen Island, illegal fishing, unregulated fishing
Journal or Publication Title: Marine Ecology Progress Series
Publisher: Inter-Research
ISSN: 0171-8630
DOI / ID Number: 10.3354/meps12248
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Copyright 2017 Inter-Research

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