Albatrosses are good omens for sailors, but are not having too much luck themselves. The population of female wandering albatrosses that nests on Antipodes Island has plummeted by two-thirds in the past 14 years.
This rapid decline has alarmed researchers Kath Walker and Graeme Elliott, who have been studying the species for two decades. There appear to be a number of causes, but the primary one is changing oceanic conditions that force the birds to forage in more northerly waters where the risk of being caught by commercial longliners is higher. Some years have seen female mortality rates as high as 20 per cent.
“We think about polar bears with despair, but it’s a rather similar sort of situation here,” said Walker in an interview with RNZ.
Antipodean albatrosses forage for squid, which is also used as bait by the longliners. While many fishers have a suite of techniques and technology to avoid bycatch, those that don’t risk birds taking the hooks and drowning with the sinking line. As Antipodean albatrosses raise only one chick, and both adults provide food during the first year, the loss of a single adult often means the death of its chick too.
Antipodean albatrosses range widely—far beyond New Zealand’s exclusive economic zone, into the stateless realm of the high seas and as far east as Chile’s continental shelf. Regional fisheries management organisations regulate fishers out there in a similar way to those in New Zealand waters, but the level of compliance and reporting of bycatch is debatable.
Without better data on where the birds are foraging—and dying—researchers are at a loss to determine the threats to the population. There are some 3000 registered longliners in the Pacific, and it’s uncertain which vessels or jurisdictions they interact with.
To complicate matters, female Antipodean albatrosses forage further to the north, in more dangerous waters, and are disappearing at a greater rate than the males, leading to a severely skewed sex ratio.
The Department of Conservation and the Ministry of Primary Industries deployed about 75 satellite-transmitting devices on Antipodean albatrosses this year, and in association with the Southern Seabirds Solutions Trust, intend to deploy the same number again next season.
The tags track the birds’ locations as they forage, and researchers can overlay this data with the position of fishing vessels operating in the area to determine the risk of contact.
If left unchecked, the Antipodes Island wandering albatross could be the first albatross species in the world to become functionally extinct.