Document ID: chunk:federal_register_of_legislation:F2022L00775:reg:18:p47
Version: federal_register_of_legislation:F2022L00775
Segment Type: reg
Provision Reference: reg 18 (pt 47/152)
Character Range: 170172–173056

to breeding grounds and allowing vast colonies to persist (Weimerskirch
  1998). The species migrates to the Northern Hemisphere during the Austral winter (Shaffer et al. 2006, Hedd et al. 2012), and in the California Current, Sooty Shearwater numbers have decreased by 90 per cent in the last 20 years (Veit et al. 1996). It remains uncertain whether this has resulted from population decrease or distributional shifts (Spear and Ainley 1999), given there is no evidence from colonies of a decrease of 90 per cent.

  Population Estimates and Trends
The global population is estimated at 4.4 million pairs, roughly equating to 19–23.6 million individuals (Newman et al. 2009, Waugh et al. 2013). In southern Chile, some colonies number up to 200,000 pairs, with the largest colony of up to 4 million individuals on Isla Guafo (Reyes-Arriagada et al. 2007). In the Falklands (Islas Malvinas), 10,000-20,000 pairs have been recorded. New Zealand supports more than 180 colonies. In 1970-1971, the colonies on the Snares Islands were estimated to support 2,750,000 breeding pairs (del Hoyo et al. 1992, Heather and Robertson 1997).
Although this is an extremely numerous species, there are persistent signs of a current decrease (Brooke 2004). In New Zealand, the number of burrows in the largest colony on the Snares Islands decreased by 37 per cent between 1969-1971 and 1996-2000, and burrow occupancy may also have decreased, indicating that an overall population decrease may have occurred (Warham and Wilson 1982, Scofield and Christie 2002, Scott et al. 2008). Some colonies on mainland New Zealand have decreased, and several colonies on offshore islands, especially in northern New Zealand, have not responded to predator control (Gaze 2000, Jones 2000, Waugh et al. 2013). However, other colonies in southern New Zealand have responded to sustained pest management with increasing shearwater numbers (Newman et al. 2009). Population estimates and trends at Australian colonies are unknown (Garnett et al. 2011).

78 Wildlife Conservation Plan for Seabirds
Species profiles

Conservation Concerns and Actions
The species is at risk from incidental capture in longline, trawl and gill-net fisheries and suffers the additional effects of depletion of prey stocks (Uhlmann 2003). A large number of deaths occur as a result of interaction with fisheries both during the breeding season and the winter migration to the Northern Hemisphere (Uhlmann 2003). The species is also subject to a legal cultural harvest in New Zealand. Harvesting of young birds ('muttonbirding') currently accounts for the take of around a quarter of a million birds annually (del Hoyo et al. 1992, Heather and Robertson 1997, Newman et al. 2008, 2009), but is unlikely to account for the scale of the observed decrease.

Past investigation into the biological impact of climatic trends led to