WELLINGTON, July 11 (Xinhua) -- The world's most endangered seal species is facing a bleak future, according to a New Zealand-led study of a now extinct population that disappeared soon after first contact with humans.
An international team of scientists led by the University of Otago has found that New Zealand's Chatham Islands, about 650 km east of the South Island, were once home to a population of sea lions.
Dr Nic Rawlence, of the University of Otago, said the unique prehistoric Chathams sea lion was genetically clearly distinct from the modern population of New Zealand sea lion that persisted in the sub-Antarctic Auckland and Campbell Islands, and the mainland today.
"The Chathams supported a large, genetically diverse population of this unique sea lion, which went rapidly extinct around 1650 AD, following Polynesian settlement of the islands only 200 years earlier," Rawlence said in a statement Monday.
The Otago team used computational modelling to determine the level of human hunting likely to have caused the Chathams sea lion extinction.
"Modelling indicated that hunting rates greater than one sea lion/person/year resulted in the extinction of native populations within 200 years of first human settlement," archaeologist Dr Justin Maxwell said in the statement.
"Sea lions were not able to withstand even low levels of sustained hunting pressure," said Maxwell.
The findings could have important implications for the continued survival of New Zealand's modern sea lions.
The New Zealand sea lion is listed as endangered in the International Union for Conservation of Nature Red List.
With only around 10,000 individuals remaining, the population is in serious decline -- births are down by 50 percent since 1998 -- with fisheries bycatch and resource competition the suspected culprits.
"The team's computer models suggest that current reported and unreported bycatch levels may be unsustainable for the long-term survival of the species," biologist Associate Professor Bruce Robertson said in the statement.
"What our research shows is that human harvesting and sea lions do not mix. Unless measures are taken to mitigate continuing bycatch levels, the outlook for our sea lions is bleak," said Rawlence.
