Open image gallery
Globally, the Grey-headed Albatross Thalassarche chrysostoma is undergoing population declines over a 90 year (three generation period) of greater than 50% satisfying criterion A4 for qualification as Endangered. The regional population has been quantified at c. 19 000 mature individuals that breed at two locations, namely Prince Edward and Marion islands. The global status of Endangered is adopted as the regional status.
The Grey-headed Albatross disperses widely across the Southern Ocean from breeding sites at several Subantarctic islands including South Georgia, Crozet, Kerguelen, Macquarie, Prince Edward Islands and Campbell as well as the Diego Ramirez and Ildefonso island groups off Chile (Prince et al. 1998). Within the region, the species breeds at two sites, namely Marion Island and Prince Edward Island, occupying a total AoO of 334 km2 (Nel et al. 2002). Adults are mostly confined south of 40° S and seldom venture into continental shelf waters with the majority of records off South Africa being of immature birds.
The global annual breeding population has been quantified at c. 192 000 mature individuals with the Prince Edward Islands holding roughly 11% of this total (ACAP 2010). The Prince Edward Island and Marion Island populations are c. 4 000 and c. 15 000 mature individuals respectively, giving a regional annual breeding population of c. 19 000 mature individuals (Ryan et al. 2009). The confidence in this regional population estimate is high.
The global population is in decline having decreased by 15% since the mid-1980s (BirdLife International 2014). Provided current trends continue into the future, declines can be expected to equate to 50% over three generations (90 years). In contrast to the global trend, the number of breeding pairs on Marion Island has increased by 2.5% per year from a low in 1975 until the early 1990s, and at a slower, but appreciable rate thereafter (Nel et al. 2002, Ryan et al. 2009). Trend information is not available for Prince Edward Island. The mean annual adult survival rate between 1998 and 2005 was 93%, which is not worryingly low but is not as high as it should be ideally (ACAP 2010). Confidence in the regional population trend estimate (Marion Island) is high.
The primary threat faced by Grey-headed Albatrosses is from the longline fishing industry (Nel et al. 2000). Satellite tracking of breeding birds from Marion Island has shown that their foraging ranges fall within areas of longlining activity for both tuna and toothfish. Birds foraging away from the Prince Edward Islands, and in particular incubating females, come into contact with intensive longline fishing effort for Southern Bluefin Tuna Thunnus maccoyii in international waters around 40-45° S (Nel et al. 2000). During the breeding season, adult male birds encounter boats targeting Patagonian Toothfish Dissostichus eleginoides in the shelf waters off the Prince Edward Islands, but incidental seabird mortalities in this fishery have been reduced to zero (Ryan 2005). Historically, Grey-headed Albatrosses made up 3.2% of all birds killed between 1993 and 1997, despite only accounting for 0.4% of birds attending the vessels (Weimerskirch et al. 2000). The shift in fishing effort away from the islands as well as implementation of mitigation measures have resulted in a decrease in the number of mortalities recorded (Nel et al. 2002). However, birds are still threatened by other commercial operations due to their circumpolar distribution. Ingestion of plastic litter may be a potential threat (Nel et al. 2002) but has to be quantified. There are no known threats to birds breeding at the Prince Edward Islands themselves, although predation of chicks by mice is of concern.
Indications of an increasing regional population suggest that general measures to reduce seabird bycatch in fisheries have been successful. The Grey-headed Albatross receives protection in South Africa under the Sea Birds and Seals Protection Act, 1973 (Act No. 46 of 1973), Marine Living Resources Act (Act No. 18 of 1998): Publication of Policy on the Management of Seals, Seabirds and Shorebirds: 2007 and the National Plan of Action (NPOA) for Reducing the Incidental Catch on Seabirds in Longline Fisheries (2008). Distribution overlaps with the Indian Ocean Tuna Commission, International Commission for the Conservation of Atlantic Tunas, Western and Central Pacific Fisheries Commission, Commission for the Conservation of Southern Bluefin Tuna and Commission for the Conservation of Antarctic Marine Living Resources. The Prince Edward Islands are listed as a Ramsar Wetland of International Importance, as a Special Nature Reserve under the Environment Conservation Act (No 73 of 1989) and the Prince Edward Islands Management Plan 1996. Various stringent guidelines are in place to prevent pollution, contamination, disturbance and introduction of pathogens or invasive organisms on the islands. Visits to Prince Edward Island are strictly controlled.
Ongoing monitoring of the population trends via annual census of adults and of large chicks should continue at Marion Island. Irregular visits to Prince Edward Island should attempt to count standardised sections of the breeding cliffs (if not the entire colony). Alternatively, aerial photography to census the cliffs should be conducted during the incubation period.
* The scale of decreases that the global population experiences suggest that longline fishing effort is more risky to this species than expected. Research into the scale of Illegal, Unregulated or Unreported (IUU) fishing in the Southern Ocean, for toothfish and for tunas, should be investigated and possibly modelled, including to assess if/how possible changes in IUU effort (spatial and temporal) might cause greater impacts on the Prince Edward Islands population.
* Vulnerability to climate change, including of prey distributions shifting polewards, which might cause increased costs for foraging, should be explored.
* Ongoing research is required to assess adult survival rates on an annual basis.
* This species is known to suffer adverse impacts from El Niño events - the mechanisms, and whether this can be mitigated in any way, should be investigated.