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How are Oceanographic Influences Effecting Scallop Fisheries?

Water quality Sustainability Politics +4 more

AUSTRALIA - A new study is looking at the effects of ocean conditions on Queensland scallop and reef fish populations.

Lucy Towers thumbnail

The research is a joint initiative of the Queensland Department of Agriculture, Fisheries and Forestry (DAFF), University of Queensland and Bureau of Meteorology, with funding from the Fisheries Research and Development Corporation and Great Barrier Reef Marine Park Authority (GBRMPA).

Lead investigator and DAFF principal fisheries biologist Dr Tony Courtney said by better understanding these environmental influences, improvements to stock assessments can be made and better advice given to Government and fishers.

"There is a strong need to better understand how the prevailing physical oceanography affects these fisheries," Dr Courtney said.

"In recent years, oceanographers have described a large offshore eddy system on the central Queensland coast, known as the Capricorn Eddy, that breaks away from the south-flowing East Australian Current to move westward onto the continental shelf.

"The eddy brings cool, nutrient-enriched oceanic water onto the shelf, which we suspect affects the population size of saucer scallops in the region.

"We will also examine the relationships between tropical cyclones and catch rates of reef fish, given the Great Barrier Reef has been hit by four major cyclones in the last five years.

"From commercial fishing data we’ve observed that catch rates of coral trout appear to fall after a major cyclone, while those of red throat emperor rise.

"These changes seem to endure for some years after the cyclone, but their exact causes are not known.

"For coral trout, it's thought the cooler waters that result from cyclones may slow down the metabolic rate of the fish, thereby affecting their feeding behaviour and ability to be caught by fishers."

The types of oceanographic data to be considered include sea surface temperature, satellite-based chlorophyll measurements, sea surface height, salinity, current strength and direction, and radii and wind speeds of tropical cyclones.

The project will use CSIRO's Bluelink ReANalysis (BRAN) 3.1 oceanograhic model of ocean temperature, salinity, currents and sea level height. It will also use fish and scallop population data including commercial fishing logbooks, underwater visual survey data and age and size data from the Australian Institute of Marine Science, GBPRMA, James Cook University and DAFF.

The study includes funding for a post-graduate student to examine fish and scallop larval dispersal patterns.