Rationale
(Changed due to Not applicable)
The regional population of Southern Giant Petrel Macronectes giganteus satisfies the criterion for regionally Vulnerable under D2 in that it breeds on two islands within the region (Marion and Prince Edward) and is thus potentially vulnerable to the effects of human activities or stochastic events which may cause it to become Critically Endangered or even Extinct in a short period. However, the populations breeding at the Prince Edward Islands are believed to be relatively secure, and it is unlikely that the species will suffer catastrophic declines in the next one to two generations. As a result, the Southern Giant Petrel was assessed as regionally Near Threatened.
Distribution
The Southern Giant Petrel breeds at ice-free sites in coastal Antarctica, Subantarctic islands, the Falklands and along the Patagonian coast of South America (Marchant and Higgins 1990, Cooper et al. 2001). Within the region, the Southern Giant Petrel breeds at both Marion and Prince Edward islands. It has an extensive pelagic range with juveniles, pre-breeders and wintering birds dispersing widely across the Southern Ocean and into subtropical waters (up to 20°S). It is present in continental South African waters in both summer and winter.
Population
The global population is estimated at c. 46 800 breeding pairs equivalent to c. 100 000 mature individuals with about 40% of the global breeding population found on the Falkland Islands (ACAP2011). Ryan et al. (2009) estimated the total Prince Edward Island population to be c. 1 350 pairs and the Marion Island population at c. 1 433 pairs. The total number of pairs at the Prince Edward Islands is c. 2 783 pairs. The confidence in this estimate is high.
Population trend
Currently relatively few published data are available to allow an analysis of global population trends in the Southern Giant Petrel. The population at Prince Edward Island remains too infrequently counted to obtain accurate trends. For instance, the 2008 count of Southern Giant Petrels on Prince Edward Island was 28% higher than the 2001 count, but this might reflect better coverage as well as inter-annual differences in breeding success. At Marion Island, the breeding population decreased from 2 500-3 000 pairs in the 1980s and early 1990s to approximately 1 500 pairs in the late 1990s (Nel et al. 2002), but has since stabilised. The collapse coincided with the short-lived Patagonian Toothfish fishery around the islands. The decline over three generations approaches the 30% threshold although Ryan et al. (2009) believes that the population has now stabilised. The confidence in the regional population trend estimate is medium.
Threats
The primary threat facing Southern Giant Petrels is incidental capture and mortality in both longline and trawl fisheries (Petersen et al. 2009a,b), although the species is less aggressive and thus apparently less vulnerable to capture than the various albatrosses. Plastic ingestion, pollution and human disturbance have been listed as threats (ACAP 2011d). The species is occasionally preyed upon by sharks (Hunter 1984) but this is not considered a major threat.
Conservation
Underway
The species receives international protection under the Agreement on the Conservation of Albatrosses and Petrels - Annex 1 and the Convention on the Conservation of Migratory Species of Wild Animals - Appendix II. Within the region it is protected under the Sea Birds and Seals Protection Act, 1973 (Act No. 46 of 1973), Marine Living Resources Act (Act No. 18 of 1998) and the National Plan of Action (NPOA) for Reducing the Incidental Catch on Seabirds in Longline Fisheries (2008). The Prince Edward Islands are listed as a Ramsar Wetland and a Special Nature Reserve. The Prince Edward Islands Marine Protected Area was proclaimed in 2013.
Proposed
Monitoring and tracking programmes to assess overlap with key fisheries should continue, and the existing measures to avoid seabird bycatch in the Patagonian Toothfish fishery should continue. Risks to breeding birds on the Prince Edward Islands should be fully evaluated.
Research
* Investigate the reasons for the lack of recovery of this sub-population after the collapse in the 1990s.
* Juvenile and immature survival rates are key population demographic parameters that remain unknown for this population. Assessing possible threats to all age- and stage-classes and both sexes should be undertaken, preferably through tracking of fledglings.
