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ESR prepress abstract   -  DOI:

Characterising seabird vessel interactions associated with demersal ocean trawling: vessel attendance depends on intrinsic and extrinsic predictors

Thomas C. Barnes, Steven G. Candy, Daniel Johnson

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ABSTRACT: Seabirds are declining on a global scale which is concerning as they play an important role in the marine ecosystem. Decline is due to multiple reasons, but harvest fisheries are a major contributor. However, the impact of fisheries appears to vary; demersal trawlers cause the mortality of many birds in some areas and very few in others. Fishery dependent monitoring is required to understand the impact on seabirds, but particularly to better understand the variable impact of demersal trawling. We employed a targeted observer program to gather data on seabird assemblages, catastrophic interactions with trawl vessels, and predictors of seabird vessel attendance. The latter is a useful proxy for catastrophic interactions and provides information on potential mitigation. Throughout the program period, 104 0942 seabirds from ~ 21 species attended New South Wales (NSW) ocean demersal trawlers. Species included seven species of petrel and albatross listed by the International Union for Conservation of Nature, including the flesh footed shearwater (Ardenna carneipes) and wandering albatross (Diomedea exulans). Two catastrophic interactions were recorded, and intrinsic and extrinsic predictors of vessel attendance (e.g. offal discharge and wind, respectively) were characterised. The results of the study will inform managers to ensure the sustainability of NSW ocean trawling and particularly the coexistence with threatened seabirds. Another demersal trawl fishery, the NSW Ocean Trawl fishery, appears to harm very few seabirds directly. Predictors of attendance such as space, time and offal discharge can potentially be used to mitigate the attractiveness of trawlers.