Climate change sees tropical fish arrive in Tasmania

Updated

The CSIRO is warning climate change is having a big impact on the country's oceans, with tropical fish turning up as far south as Tasmania.

A major report on oceans and climate change, released today, says the damage under the sea is much clearer than when it released its last report on the subject three years ago.

As well as causing a southern migration, climate change is causing a decline in some temperate fish stocks and ocean acidification is beginning to affect shellfish.

The water at Hobart's Taroona Beach is chillier than what most Australians are used to, but increasingly it is home to northern visitors of the finned variety.

Gretta Pecl runs a website called Redmap, and says that divers and fishers are increasingly documenting a range of sea creatures not normally seen in Tasmanian waters.

"The southerly shift in distribution that we've seen in species has been from a range of species, across the board," she said.

"So some are bony fish, sharks and rays, octopus, lobsters, a whole range of species that are either showing signs of starting to move into Tasmanian waters, or showing up more frequently, and we're yet to establish exactly what that might mean."

Dr Pecl works for the Institute of Marine and Antarctic Studies and the amateur photos are checked out by scientists.

Professor David Booth, a marine ecologist at Sydney's University of Technology who contributed to the report, said the institute's findings are supported by the CSIRO report.

"Tropical reef fish are actually making an appearance," he said.

"Our long-term studies, over at least a decade, have showed the number of tropical species very much year-to-year, but in those strong east Australian current years they're more prevalent.

"Over the last 30 or 40 years we're seeing many more tropical species down toward Sydney and down in Tasmania than we did before."

'Unprecedented' change

The report found the range of temperature rise varied dramatically, with the east coast of Tasmania and parts of Western Australia hardest hit.

Overall the rise in sea surface temperature is about one degree centigrade over the last century.

However, Professor Booth says snorkelers should not be too excited about the changing underwater world.

"In this case the rapidity of the change is probably fairly unprecedented," he said.

"Now everyone is probably thinking what's wrong with having some lovely tropical species down here, but the flip side, of course, is firstly any interaction with normal species and then independent of the colder water species not being able to live as far north and in my home state of New South Wales could really have a risk of a loss of fisheries."

The CSIRO believes climate change will continue to alter the seas.

Dr Pecl said there are plans for a national launch of the Redmap website.

"From the end of November, we will be launching across Australia," she said.

"Fishers and divers from all over the country will be able to submit sightings of species that we think are unusual and we get those checked out by a scientist."

Topics: environment, climate-change, environmental-impact, science-and-technology, animal-science, biology, marine-biology, conservation, marine-parks, fish, taroona-7053, australia, university-of-technology-sydney-2007, nsw

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