Warming Indian Ocean – impacts on fisheries

Posted by Josette Dunn on 31st March 2010

The impacts of a warming Indian Ocean on Western Australia’s climate, environment and fisheries was discussed in Perth last week by scientists at a Western Australian Marine Science Institution (WAMSI) symposium.

A focus area of the discussions was on understanding and forecasting the Indian Ocean Dipole (IOD) – a climate pattern in the Indian Ocean associated with a basin-wide shift in sea temperatures, winds and rain.

According to Dr Ming Feng – a CSIRO Wealth from Oceans Flagship oceanographer who is collaborating with the WA Department of Fisheries to understand climate variability and change impacts on fisheries recruitments in WA – researchers already know that remote climate influences from the Pacific Ocean have a large effect on the marine environment, the regional climate off the west coast of WA, and some of WA’s most valuable fisheries.

“But our understanding of how climate influences in the Indian Ocean affect the WA environment and fisheries is still relatively primitive,” Dr Feng says.

“In our WAMSI projects, we are looking to improve our forecast models of climate anomalies and future climate projections under enhanced greenhouse gasses in the atmosphere.This will help us better understand the link between variability of the ocean currents and fisheries recruitments, particularly the Western Rock Lobster fishery.

“We’ve been using numerical models that simulate the Leeuwin Current and shelf circulation so we can investigate whether a string of poor puerulus (juvenile) Western Rock Lobster settlement levels may be linked to IOD events.”
“In our WAMSI projects, we are looking to improve our forecast models of climate anomalies and future climate projections under enhanced greenhouse gasses in the atmosphere.”
Dr Ming Feng

The team has found that during IOD events, weakened westerly winds in late winter are evident, which may not facilitate the larvae returning to the coast.

“There’s also a possible link between IOD events and reduced storm activities off the south-west coast. And our model results show that the Leeuwin Current may increase in strength the year after a dipole event,” Dr Feng says.

According to the WA Department of Fisheries’ Dr Nick Caputi; “With the WA fisheries worth more than $400 million per annum, of which the Western Rock Lobster is among the top three contributors, improving our understanding of Indian Ocean currents and their influences is of vital importance.”

The Indian Ocean plays an important role in a warming world, as CSIRO scientists have identified that sea surface temperatures in the tropical Indian Ocean have risen relatively faster in recent decades with increases of sea surface temperature between 0.6 and one degree seen around the WA coast in the past 50 years.

These findings and a diverse range of Western Australian marine science were discussed during the one-day symposium, held at CSIRO in Floreat. The WAMSI symposium was hosted by CSIRO’s Wealth from Oceans Flagship, the Bureau of Meteorology and the Australian Institute of Marine Science.