At-sea distribution of Gibson's and Antipodean wandering albatrosses, and relationships with longline fisheriesSubmitted by osnz-admin on Tue, 03/15/2011 - 22:47
|Title||At-sea distribution of Gibson's and Antipodean wandering albatrosses, and relationships with longline fisheries|
|Publication Type||Journal Article|
|Year of Publication||2006|
|Authors||Walker, K, Elliott, G|
|Type of Article||article|
|Keywords||Diomedea spp., harness trials, longline fisheries, satellite telemetry, Wandering Albatross|
Satellite telemetry was used between 1994 and 2004 to identify the distribution of 2 closely-related species of wandering albatross, Gibson’s (Diomedea gibsoni) and Antipodean (D. antipodensis), which breed in the New Zealand subantarctic. Trials of methods of attaching transmitters revealed that harnessed transmitters decreased foraging efficiency and increased mortality, whereas transmitters glued or taped on birds had little effect. There was some overlap in the species foraging ranges, but D. gibsoni mostly foraged in the Tasman Sea and D. antipodensis in the Pacific Ocean east of New Zealand. For both species the range of non-breeding birds was larger than that of breeders, but the core areas used by both breeders and non-breeders were similar. Non-breeding male D. antipodensis had the largest range, foraging off the coast of Chile, Antarctica and in the tropical South Pacific. In comparison, the range of D. gibsoni was small, with non-breeding male and female birds foraging westward to the south-eastern Indian Ocean but avoiding Antarctic waters. Individuals of both species and all stages of maturity had preferred but large foraging areas which lasted many years. Some seasonal trends in distribution were found. Both species preferred to forage at the outer edge of shelves and over seamounts, particularly where there were strong currents or eddies and productivity was enhanced, as well as over deep water. Over the past 40 years, longline fisheries used a minimum 89% and 53% of the range over which our study tracked D. gibsoni and D. antipodensis respectively. Of 18 D. gibsoni and 35 D. antipodensis banded birds recovered dead since 1971, 22% and 83% respectively were related to fisheries. The areas where closures of fisheries would be most likely to reduce bycatch are identified.