Warming waters send tropical fish species south

Tue 24 Aug 2010

Scientists from various research organisations report that climate change is turning the environment upside-down, with fish species from Queensland waters migrating south to escape the ever warmer waters.

Species such as groper, tiger sharks and even warm-water fish like coral trout are becoming more frequently found in Tasmania.

Scientists also have recorded yellowtail kingfish and snapper heading south, while north Queensland barramundi and threadfin salmon are being caught in Moreton Bay off Brisbane and on the Gold Coast.

Scientists say it shows how climate change is redistributing species. They have identified 45 species – including 30 per cent of inshore Tasmanian fish families – relocating.

Others are warm temperate surf species such as silver drummer, rock blackfish and rock flathead, and warm-water tuna and billfishes.

Australian National Fish Collection curator Peter Last said yesterday up to 19 species or 5 per cent of Tasmanian coastal fish such as the maugean skate had declined or were possibly locally extinct.

'At the same time many warm temperate species have moved in,' Dr Last said. 'The problem is that in southern Tasmania, shallow cold-water species have nowhere to escape warmer conditions.'

Dr Last said he was surprised when a coral trout, a Great Barrier Reef species, was caught at Port Arthur.

'I didn't believe this guy when he said he had caught one until he brought it in,' Dr Last said. 'We also had a big Queensland groper sneak up behind people on a dive off Bicheno. We get great whites so it scared the heck out of them. I also had an aquarium collector with a heap of Queensland species off Eden (NSW).'

Dr Last said odd northern species had always travelled down the east Australian current, but it now extended 350km
further south than about 65 years ago. Water temperatures had risen 2°C.

'Species like groper and tiger sharks are normally not seen much south of Sydney and tropical fish that turn up in summer in Botany Bay and then die off, are persisting,' he said.

CSIRO oceanographer Ken Ridgeway said the current was strong to about Eden in the 1940s but powerful flows now continued through to Tasmania because of a switch in winds generated by changing ozone levels and warming.

Wildlife Preservation Society president Simon Baltais said evidence of dramatic species moves was mounting.

'The tragedy is scientists have been warning of this for about three decades yet nothing has been done by governments at a policy level,' he said. 'It's surprising how many fools believe (climate change) sceptics despite evidence being so overwhelming.'

Dr Last said it was logical to expect species such as barramundi and king salmon to increase in Moreton Bay and he expected survey work near Perth, WA, to show major shifts.

Dr Last, the CSIRO and Tasmanian Aquaculture and Fisheries Institute have published a paper on the changes in the journal 'Global Ecology and Biogeography'.

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