Sea lions fitted with tracking technology

(clockwise from left) Massey University wildlife vet Kerri Morgan, DOC marine mammal scientific...
(clockwise from left) Massey University wildlife vet Kerri Morgan, DOC marine mammal scientific officer Dr Louise Chilvers, biologist Jacinda Amey, DOC coastal ranger Jim Fyfe, Otago University doctoral student Amelie Auge, and Dunedin vet Tony Matthews.
Ready to go... This lightweight recorder and tracking device, with aerial, is temporarily glued...
Ready to go... This lightweight recorder and tracking device, with aerial, is temporarily glued to Aurora.
Wildlife encounter... Three New Zealand sea lions gather on the Otago Peninsula’s southeast coast.
Wildlife encounter... Three New Zealand sea lions gather on the Otago Peninsula’s southeast coast.
Aurora (pictured with her pup) dozes for a few moments after the device was fitted.  Photos by...
Aurora (pictured with her pup) dozes for a few moments after the device was fitted. Photos by Gerard O'Brien

A new Department of Conservation research initiative involving the satellite tracking of New Zealand sea lions is also highlighting the special qualities of the Otago Peninsula wildlife, researchers say.

Dr Louise Chilvers, a Doc marine mammal scientific officer, of Wellington, said the sea lions now found on the Otago Peninsula were a ‘‘unique and incredibly special population''.

About 70 of the protected animals are based there now.

The females among them constitute the first breeding colony of sea lions to reappear on the New Zealand mainland since hunting and sealing wiped them out there by the early 1800s.

The peninsula's Royal Albatross Colony is the only mainland albatross colony in the world.

The yellow-eyed penguin, one of the world's rarest penguin species, has also adopted the Otago Peninsula and the Catlins as its main breeding areas in the South Island.

A team of scientists and support staff this week fitted satellite tracking tags and time depth recorders to four female sea lions on the Otago Peninsula's southeast coast in order to gather data about their foraging (food gathering) behaviour.

If successful, the initial pilot study will usher in a three-year research programme, with four or more further female sea lions studied each year.

This is the first time such satellite-linked devices have been used to track sea lions based on the New Zealand mainland.

The four animals were also measured, weighed and inspected for external parasites. Milk and blood samples were taken and examined for pathogens, pollutants, and to determine the overall health of the animals.

The combined satellite tracking devices and timedepth recorders used in the Otago research will provide regular information on the location of the foraging sea lions and the depth and duration of their dives while searching for prey.

The small devices were mounted on neoprene and then glued to the hair of the sea lions. The equipment would be retrieved after one or two months by cutting through the neoprene, organisers said.

A very high frequency (VHF) transmitter was also attached to each of the study animals to help relocate them when back on land.

The neoprene layer that remained on the sea lions would fall off during their annual moult.

The VHF transmitters would be left on for the life of the battery - about six months - allowing researchers to continue further monitoring.

Shaun McConkey is the Dunedin-based chairman of the New Zealand Sea Lion Trust, which promotes protection, conservation and education about the sea lion, which has long been a protected species.

The fact that sea lions had joined the royal albatross and the yellow-eyed penguin in opting to breed on the Otago Peninsula was ‘‘another indication that this is a great area,'' Mr McConkey said.

‘‘It's got to be a pretty good indication that there is a real value here for the wildlife and you would assume the main reason would be food accessibility,'' he said in an interview.

Kate Rushbrook, the Tourism Dunedin international sales manager, said the growing sea lion colony on the peninsula was adding to the city's reputation as a wildlife tourism centre.

The scientific research being undertaken was a positive step which would ultimately enable visitors, undertaking guided tours, to receive more information about sea lions and their activities, Mrs Rushbrook said.

University of Otago zoology student Amelie Auge will be undertaking much of the Otago sea lion research for her PhD thesis, which will be supervised by Dr Chilvers.

Dr Chilvers said that, at this stage, much of the behaviour of the sea lions once they left the Otago Peninsula coastline in search of food remained obscure.

‘‘We know nothing about their feeding behaviour, apart from a little bit about diet,'' she said.

Knowing more about where the sea lions roamed in search of food, including whether they visited the edge of the continental shelf, about 25kms offshore, would help support improved conservation and management planning for the threatened marine species.

The Otago study is part of a wider study, led by Dr Chilvers, also involving sea lions at the Auckland Islands.

Satellite tracking and timedepth recorders have previously been used by Dr Chilvers to study foraging behaviour by New Zealand sea lions on the Auckland Islands, about 700km south of Dunedin.

More than 99% of the estimated 12,000 remaining New Zealand sea lions are based in the Auckland Islands, which seems a physiologically marginal location for the animals, which once were found throughout mainland New Zealand.

Satellite data from the Auckland Islands shows female sea lions with young to feed have ranged up to 175km offshore in search of food and reached depths down to about 600m-which is the deepest dive ever recorded for any sea lion or fur seal species in the world.

The satellite tracking equipment now being used near Dunedin had provided a lot of information about sea lion foraging behaviour in the Aucklands.

‘‘We hope to have the same success here,'' she said.

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