Tropical fish species are showing up in Australian waters as a response of marine life to climate change. The report on oceans and climate change, released Friday, called the movement a southern migration.
CSIRO, which prepared the report, said that besides the migration of tropical fish species to cooler waters, climate change is also causing a decline in some temperate-zone fish stocks and ocean acidification is starting to affect shellfish.
The migration was documented by the Web site Redmap based on reports from divers and fishers of sightings of sea creatures normally not seen in Tasmanian waters.
Among the species spotted were bony fish, sharks, stingrays, octopuses and lobsters, said Gretta Pecl of the Institute of Marine and Antarctic Studies, which runs Redmap.
Professor David Booth, a contributor to the CSIRO report and marine ecologist at the University of Technology in Sydney, said more tropical species have been observed moving toward Sydney and Tasmania over the last three to four decades but their numbers grew dramatically in the past 10 years.
"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 loss of fisheries," he told the Australian Broadcasting Coop.
Dr Elvira Poloczanska, lead author of the Climate Adaptation Marine Report Card 2012 study, said the migration phenomenon creates a lot of uncertainty over its long-term impact on marine life.
"The potential is there for animals and plants to shift, but whether they do or not depends how well they can deal with changes in their current environment,"she told AAP.
Nature lovers can view the sightings of the tropical species when Pecl launches Redmap nationally by the end of November.
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