Endangered albatrosses under threat from commercial fishing
Endangered albatrosses under pressure due to commercial fishing, UC researcher says
November 7, 2012
Endangered albatrosses which nest in New Zealand are under increasing threat as they compete for the same food in the same waters as major commercial fisheries, a University of Canterbury (UC) researcher said today.
UC PhD student Lorna Deppe said both the longline and trawl fisheries imperil albatrosses at sea. She has spent three years studying the movements of Chatham albatross, Northern Buller's albatross and Northern Royal albatross, all of which are endemic to New Zealand.
New Zealand waters are the breeding grounds for 60 percent of albatross species worldwide. The Chatham albatross is an extreme example as its breeding population comprises only about 5000 breeding pairs, all of which breed on a single island, The Pyramid, in the Chathams.
She said New Zealand has a huge responsibility for the conservation of such species. However, far ranging species like albatrosses do not stick to jurisdictional boundaries and it was important to know where they went once they finished breeding. The development of small electronic tracking devices now allows scientists to follow birds wherever they go, even across entire ocean basins.
``Using geo-locator devices, I was able to track both Chathams and Northern Buller's albatrosses from New Zealand and I found highest densities of wintering birds in northern Chilean and Peruvian waters, an area known for being one of the world’s most productive fishing grounds.
``Since bird and man go for the same resource, this is not necessarily a surprise, but poses a two-way threat: mortality as by-catch in fishing gear and potential depletion of food needed to refuel during winter due to human over-fishing. It’s similar for the Northern Royal albatrosses which winter on the Patagonian shelf in Argentina.
``And it’s the same again for the Chatham albatross during the breeding season. I studied the birds’ foraging movements over three years and found they restricted their range to the Chatham Rise, an area intensely used by commercial fishing operations.’’
In the last two decades, a better understanding of the movements of seabirds and their habitat requirements, had taken on new urgency, she said.
A total of 19 out of 22 albatross species are currently considered threatened. In some cases, the decline is associated with habitat loss, pollution and the introduction of invasive animals onto nesting islands. However, for most species, the primary threat appears to be increased adult mortality associated with commercial fisheries, Deppe said.
``Due to naturally low population numbers and low reproduction rates, adult mortality has a particularly strong impact on population dynamics. Many species are in decline.
``Given the threatened status of many species, my objective has been to answer questions about the distributional patterns of albatrosses at sea. One particular aim has been to provide a year round overview on which areas become important at different stages of the life cycle. Such information would allow a better understanding of when and where conservation action may be needed.
``It is hoped that the new insights into distributional patterns this work provides will benefit the conservation of albatrosses and in particular New Zealand's role in this work.’’
Deppe is carrying out her thesis under the
supervision of UC Associate Professor Jim Briskie and Dr
Paul Scofield of the Canterbury