An Australian sea lion at Seal Bay on Kangaroo Island has tested positive for H5 avian influenza, South Australia’s environment minister, Emily Bourke, confirmed on 13 September; the state government’s own testing update for that day lists the animal as a newly confirmed event, one of 290 in South Australia so far. It is the first Australian sea lion known to have contracted the virus. The first mammal case in the state — and in Australia — was a long-nosed fur seal detected in August; since then two further fur seals and a number of little penguins have also tested positive, according to the account published by the Australian Broadcasting Corporation. Tours at Seal Bay have been moved off the beach and onto the boardwalk.
The significance is less the single animal than the address. The Australian sea lion is a species whose entire population numbers fewer than twelve thousand, about eighty-five per cent of them in South Australian waters, and which the ABC reports has been declining at roughly two per cent a year. Seal Bay is among its best-known and most closely watched colonies. A pathogen that has moved through seabird and then marine-mammal populations elsewhere in the world arriving at a small, already shrinking, geographically concentrated population is a different proposition from the same pathogen arriving somewhere abundant.
Australia’s federal agriculture department separately records H5 high-pathogenicity avian influenza in samples taken from southern elephant seals on Heard Island, a sub-Antarctic external territory — a detection confirmed late last year — and directs the public to report suspected cases to the national emergency animal disease hotline. The mainland and the sub-Antarctic are now both accounted for in the department’s own material.
Seal Bay will keep receiving visitors, from a boardwalk, while the colony is watched. That is most of what can be done.