WELLINGTON, Jan 29 (Reuters) - Baffled experts prepared on Thursday to investigate the mysterious deaths of about 700 New Zealand sea lion pups on a remote sub-Antarctic island.
New Zealand's Department of Conservation (DOC) said one of its veterinarians had been studying the New Zealand sea lions -- one of the world's rarest -- at the country's main breeding colony in the Auckland Islands and had discovered the dead mammals on Wednesday.
"DOC is treating the deaths as very serious. We are extremely concerned to find such a large number of dead sea lion pups and will be doing our best to find answers as soon as possible," marine mammal expert Mike Donoghue said.
Conservation Minister Nick Smith said the sea lions, with a population of between 11,000 and 15,000, were the most endangered in the world.
"We have a special responsibility to ensure New Zealand sea lions survive," he said in a statement.
Preparations were being made on Thursday to fly pathology and sampling equipment to the islands so that the dead animals could be analysed.
"At this stage, there are three possible causes -- a virus, a bacteria or a toxic algal bloom. Until tests are conducted, we won't know what has caused these deaths," Donoghue added.
All the dead animals appeared outwardly healthy and in good condition.
Establishing the cause of death could take up to three weeks, officials said.
Meanwhile, the World Wide Fund For Nature (WWF) called for the immediate suspension of the start of the annual squid fishing season, due to begin next week.
The New Zealand, or Hooker's, sea lion is increasingly threatened by drowning after getting entangled in squid trawler nets used to harvest the prolific squid population with which the sea lions share their habitat.
Typically, more than 40 large boats fish the waters from January until May or June each year, chasing a quota of 30,000 tonnes of squid with an estimated value of U.S. $32 million.
Last year the government stopped the fishing in late March after estimating that more than 100 sea lions had died in squid nets.
The WWF said the government should delay the opening of the squid fishery "at least until the cause of the deaths is known."
Smith said the government was ready to consider further steps, but only if the population was shown to be at risk following the incident.