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Marine Ecology Progress Series

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MEPS 428:289-301 (2011)  -  DOI:

White-capped albatrosses alter fine-scale foraging behavior patterns when associated with fishing vessels

Leigh G. Torres1,*, David R. Thompson1, Stuart Bearhop2, Stephen Votier3, Graeme A. Taylor4, Paul M. Sagar5, Bruce C. Robertson6

1National Institute of Water and Atmospheric Research Ltd., Kilbirnie, Wellington 6021, New Zealand
2School of Biosciences, University of Exeter, Penryn, Cornwall TR10 9EZ, UK
3Marine Biology and Ecology Research Centre, University of Plymouth, Plymouth PL4 8AA, UK
4Department of Conservation, PO Box 10420, Wellington 6143, New Zealand
5National Institute of Water and Atmospheric Research Ltd., Riccarton, Christchurch 8011, New Zealand
6Department of Zoology, University of Otago, Dunedin 9016, New Zealand

ABSTRACT: Incidental bycatch of seabirds in commercial fishing activities is known to cause declines in seabird populations. However, the full impacts on the ecology of seabirds, including effects on seabird distribution and behavior, through the association with fisheries are not fully understood. We developed a novel method to integrate fine-scale GPS tracking data from the foraging trips of ­25 white-capped albatross Thalassarche steadi within sub-Antarctic New Zealand with fishing effort distribution data to (1) quantify fine-scale overlap between individual albatrosses and individual vessels and (2) characterize behavioral changes in albatrosses when they are associated with fishing vessels. Overlap between vessels and albatrosses occurred in 68% of tracks. However, albatrosses demonstrated high variability in foraging trip destinations and association rates with fishing activity, both between and within individuals. Eight tracks never overlapped a fishing vessel. Of the 17 tracks that did overlap, a range of 2 to 73% of foraging effort on each trip occurred while overlapping a fishing vessel. Albatross foraging behavior was characterized by a significantly slower and straighter path when overlapping vessels. This study highlights the utility of GPS tags to examine the fine-scale distribution of seabirds in relation to fishing activity, revealing how effects of fisheries on marine megafauna may extend beyond mortality and injury as well as population numbers. However, results are currently constrained, not only by limited tracking data sets, but also by the quality ­(spatio-­temporal resolution) and availability of fishing effort data. Critical conservation issues related to the effects of fisheries on threatened marine megafauna cannot be fully addressed without ­comparative data sets with resolution equal to GPS tags.

KEY WORDS: Fisheries interaction · Foraging behavior · GPS tagging · Seabirds · Spatio-temporal scale · Telemetry · New Zealand · Squid trawl fishery

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Cite this article as: Torres LG, Thompson DR, Bearhop S, Votier S, Taylor GA, Sagar PM, Robertson BC (2011) White-capped albatrosses alter fine-scale foraging behavior patterns when associated with fishing vessels. Mar Ecol Prog Ser 428:289-301.

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