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POP2012-08 Foraging ecology of the Pitt Island shag (PDF, 2527K)

Summary

The Pitt Island shag (Stictocarbo featherstoni) is endemic to the Chatham Islands, New Zealand. It is presently classified as Nationally Critical (Robertson et. al. 2013), and was identified at a high-moderate risk from fishing (Rowe 2013), primarily from poorly observed set net and pot and trap fisheries.

While there is limited knowledge on the breeding biology and life history parameters of this species (Taylor 2000), the population trends are well known with three censuses having been conducted to count the number of breeding pairs. The first systematic census was in 1997 when 729 pairs of Pitt Island shag were counted (Bell & Bell 2000); the second in 2003 found 547 pairs (Bester & Charteris 2005); and the third in 2011 estimated 434 pairs (Debski et. al. 2012). This represented a 40% decline over the 14 year period since 1997. Debski (et. al. 2012) concluded that at sea factors are likely to be driving the population declines.

A low level of Pitt Island shag bycatch has been reported historically from the commercial Rock Lobster fishery from the Chatham Islands (Bell & Bell 2000; Bell 2012). With little knowledge about the foraging behaviour of Pitt Island shags it is difficult to quantify the risk of commercial pot fishing to Pitt Island shag.

This study aimed to describe the foraging ecology of Pitt Island shag using GPS devices and time depth recorders. 

Publication information

This report was commissioned by the Department of Conservation, Project POP2012-08

By M. Bell