Climate Change Threatens Australian Tuna Fisheriesff

By Michael Perry

Climate change threatens Australia’s A$2.1 billion (US$1.6 billion) commercial fishing and aquaculture industry, but may create new wild fisheries as tropical marine species move south as sea temperatures rise.

Changes in sea temperatures, currents, winds, rainfall, sea levels and extreme weather events threaten to adversely affect fish and shellfish numbers, said a report by the Commonwealth Scientific & Industrial Research Organization (CSIRO).

”It is apparent that climate change will impact the biological, economic and social aspects of many fisheries,” said the CSIRO report released on Monday.

”South-east fisheries are most likely to be affected by changes in water temperature, northern fisheries by changes in precipitation, and western fisheries by changes in the Leeuwin Current (a warm southerly current), said the report.

It said many marine species “may be lost as the climate continues to warm” and alters the island nation’s two main ocean currents, the East Australian Current and the Leeuwin Current, which support several commercially important species like tropical tuna,  rock lobsters, scallops, sardines, and whitebait.

Australia’s A$220 million salmon industry off the southern island state of Tasmania could be the hardest hit as salmon are already cultivated close to their upper thermal limit.

By 2030 sea surface temperatures in the South Tasman Sea are expected to rise by 0.6 to 0.9 degrees Celsius and along the northwest coast of Australia between 0.3 and 0.6 degrees Celsius, says Australia’s Bureau of Meteorology.

The CSIRO report said a change in rainfall could reduce catches of barramundi, prawns and mud crabs in northern fisheries of Queensland and the Northern Territory. Rainfall patterns affect nutrient levels and algal blooms containing toxins

Coral bleaching as a result of higher sea temperatures could have flow-on effects for reef-associated species, such as coral trout and red emperor.

”This report is yet another reminder that climate change imposes costs on this nation -- costs not only in terms of our way of life, but in terms of the economic costs to our industries and to our communities,” said Climate Change Minister Penny Wong.

”Climate change impacts will vary by region and that many impacts are expected to be negative, with some data suggesting that effects may have already occurred,” Wong said.

”The report finds there may be new opportunities for some wild fisheries where tropical species shift southward.”

Australia’s aquaculture industries would have to adapt to climate change through selective breeding and by regulating their marine environments, said the CSIRO report.

”Australian fisheries and aquaculture management policies do not currently incorporate the effects of climate variability or climate change in setting harvest levels or developing future strategies,” said the report.