University of Sydney, NRKI collaborate to save Australia sea lions

Researchers from the University of Sydney and rangers from Natural Resources Kangaroo Island are collaborating to conducting world-first research on KI's endangered sea lions.

For the first time, a colony of sea lions in Australia is being treated with a topical anti-parasiticide and then monitored long term for health and survival.

Farmers and animal owners would recognise the name ivermectin that is being used, commonly used to treat a range of animals.

NRKI's research, education and operations coordinator at Seal Bay Conservation Park, Melanie Stonnill was one of the speakers in a Science Week presentation organised by the Kangaroo Island Victor Harbor Dolphin Watch at the Aurora Ozone Hotel in Kingscote on Thursday, August 15.

Ms Stonnill gave a fascinating update on the current winter pupping season currently underway at Seal Bay, as well as the work to understand a relatively high rate of sea lion infant mortality.

She opened her talk however with the recent release of a study by the South Australian Research and Development Institute that looked at the impact of fur seals on fish stocks.

Long nosed fur seal populations are recovering, while Australian sea lion numbers continue to decline.

The debate about the decline on South Australia's snapper stocks has seen some blame fur seals. But the study found that sea lions and fur seals only take a very small percentage of fish.

And counter intuitively or opposite to what one would perhaps expect, the more fur seals there are the more fish there are, with a healthy population of predators leading to more prey.

But the research being undertaken at Seal Bay is on the much rarer and quite different Australia sea lion.

Latest Seal Bay sea lion colony figures after the most recent count were that there has been 146 pups birthed this season, with 24 of those deceased.

This was a mortality rate of 16 per cent, which currently was on track to be the best mortality in the last nine breeding seasons, since 2007, she said.

Australian sea lions on the beach at Seal Bay. Photo University of Sydney

Australian sea lions on the beach at Seal Bay. Photo University of Sydney

Population decline

Led by Dr Rachael Gray, from the Sydney School of Veterinary Science, in the Faculty of Science, the research is investigating the effects of hookworm, environmental pollutants like heavy metals, and human-associated bacteria on mortality of sea lions in the first one-and-a-half years of their lives.

"Sea lion populations will continue to decline if we don't do something to save these charismatic and iconic marine mammals," said Dr Rachael Gray.

"Losing sea lions is not just an unacceptable loss of another Australian mammal, but has wider consequences for the ecosystem, as sea lions are top-end predators, so their numbers effect the numbers of many other species of animals in the ecosystem."

Both sea lions and fur seals are marine mammals in a group called pinnipeds, which also includes walruses.

Sea lions are larger, have visible ear flaps, can rotate their handflippers and are less social and mostly solitary in the water, coming ashore in groups once per year to mate.

Fur seals, such as the long nose fur seal found on Kangaroo Island, are smaller, less adept at walking on land and are social and hang out in colonies on the coast.

While the population long-nosed fur seals, previously and incorrectly called New Zealand fur seals, continues to recover, Australian sea lions continue to decline at between 1 and 4 per cent per year.

Sea lions around the world are endangered, in part due to humans hunting them in the 19th century, where whole colonies were wiped out.

Sealing stopped in Australia in the 1920s, but population numbers of all pinnipeds have taken a long time to recover. Current human threats are increasingly being recognised as likely to be contributing to population declines.

The Australian sea lion is listed as endangered by the International Union for Conservation of Nature (IUCN) and vulnerable by the Australian government's Environment Protection and Biodiversity Conservation Act.

Australian sea lion numbers are estimated to be around 12,500 individuals - this small population makes the Australian sea lion one of the rarest pinniped in the world.

Dr Rachael Gray (centre), with her PhD students Mariel Fulham (left) and Shannon Taylor (right), in the laboratory analysing sea lion blood and fur samples.

Dr Rachael Gray (centre), with her PhD students Mariel Fulham (left) and Shannon Taylor (right), in the laboratory analysing sea lion blood and fur samples.

Pup mortality

Dr Rachael Gray, from the Sydney School of Veterinary Science in the Faculty of Science, is conducting world-first research on sea lion pup mortality.

To work out why our Australian sea lion numbers are decreasing and what we can do to help them recover, Dr Rachael Gray and her team are setting up a world-first topical treatment trial treating and then monitoring sea lion pup health and mortality, starting in July 2019.

Hookworm infects the intestines of 100 per cent of the Australian sea lion pups, so the team are using a novel and minimally invasive treatment for hookworm and monitoring what effect it has on pup mortality.

"Many Australian sea lion pups die from intestinal hookworm infection, so we want to see what effect treating the hookworm has, not just on the mortality directly from hookworm, but also death from other causes, such as accidental injury from adults and pollution," Dr Gray said.

"Our team has previously shown that an injectable form of hookworm treatment is effective, but we have recently piloted a topical treatment - which is easy to apply on the sea lion pup coat - and found that it is just as effective at treating hookworm."

"We're looking at how eliminating hookworm can increase survival from other factors that are also killing sea lion pups: a system weakened by hookworm, makes the sea lions more vulnerable to all sorts of other factors that can kill them."

The team, including Dr Gray's PhD students Mariel Fulham, Scott Lindsay and Shannon Taylor, are now at the exciting point of setting up the first large-scale topical treatment and long-term pinniped disease investigation anywhere in the world.

"We're going to treat sea lion pups with a spot-on anti-parasite treatment in the Seal Bay colony, and monitor them for a year and a half to see how the treatment not only improves pup health, but also survival to breeding adult, and hopefully eventually leads to population recovery."

Their innovative holistic investigation will simultaneously determine for the first time whether treating a naturally occurring parasite like hookworm alters the beneficial intestinal bacteria in sea lions, or reduces colonisation from human associated bacterial contaminants like Escherichia coli - commonly found in human sewerage.

The results of their experiment will be transformative in the wider context of preserving an endangered species by developing an effective disease and conservation management tool.

This project builds on nearly 14 years of strong, supportive and productive cooperation with the South Australian Department for Environment and Water (DEW), who manage the Seal Bay population of sea lions on Kangaroo Island and is a collaboration with researchers at Macquarie University and the University of Adelaide.