Dr Nicole Kirchhoff analysing farmed bluefin tuna and a farming centre on the right. (Photo: www.amc.edu.au/Stock File/FIS)
Tuna farmed farther from shore fare better: study
Monday, October 15, 2012, 23:40 (GMT + 9)
Southern bluefin tuna (Thunnus maccoyii) in Port Lincoln are larger and healthier when raised km offshore instead of near the shore, where they are normally farmed, as it was shown by a study carried out by University of Tasmania researchers.
The results of the study, which tracked 10,000 tuna raised closer to shore and 10,000 tuna reared farther away, were published in the international journal PLoS ONE.
Tuna farmed 50-60 km from shore, in deep, turbulent waters gained weight twice as fast as fish reared closer to the shore (usually 20 km away) and had better survival rates and superior health, according to the findings -- the world’s first commercial-scale trial of offshore fish development.
Lead researcher Dr Nicole Kirchhoff said this constitutes the first study to demonstrate it was possible to farm fish offshore and on a commercial scale, Fresh Science reports.
“Our results indicate a promising economic future for offshore development,” Kirchhoff said.
“The fish had fewer parasites and they were in overall better condition than fish maintained near the shore. As previous Commonwealth Scientific and Industrial Research Organisation (CSIRO) research demonstrates, happy and healthy animals not only taste better, but are also better for you,” the researcher added.
The farther offshore waters at the study site were twice as deep as traditional near-shore farming areas and enjoyed stronger currents, winds and waves. They also had lower levels of sealice and reduced blood fluke.
The study consisted of monitoring and sampling the tuna reared offshore during a full five-month commercial season. Researchers analysed 15 measurements of health, stress and condition.
"Although for decades there had been worldwide interest in the economic development of offshore farming, environmental and economic uncertainties had gotten in the way and prevented this kind of commercial expansion," Kirchhoff said.
“We’ve found that farming further from shore actually has benefits beyond fish welfare and commercial success,” she noted. “Globally, moving aquaculture operations offshore may reduce interactions with urban populations and inshore environmental concerns.”
The research also found that transporting aquaculture offshore might be necessary in the future due to climate change.
The researchers believe that more research and development will be needed before large-scale offshore commercial development can take place.
The study was funded jointly by the Australian Southern Bluefin Tuna Industry Association and the Fisheries Research and Development Corporation, AAP reports.
Kirchhoff is one of 12 early career scientists unveiling their discoveries to the public for the first time as part of Fresh Science, a national programme sponsored by the Australian Government.
By Natalia Real