Flying Fish Part Of New Effort To Breed Endangered Tuna

May 19, 2009

Release from: Independent Weekly (Australia)

A delicate operation to airlift millions of dollars worth of Southern Bluefin Tuna ashore for a world-first breeding program has gone off without a hitch.

The tuna, each weighing as much as 200kg, were transported on Monday from sea pens off South Australia's Eyre Peninsula to an on-shore breeding facility at Arno Bay.

They will become part of a world-first breeding program for Southern Bluefin Tuna - a critically endangered, highly migratory species critical to food security for many people around the world.

Despite being listed on the IUCN Red List as "critically endangered" the species is still widely fished.

Under the breeding program, fingerlings were successfully produced for the first time in March. Commercial production of the first aquaculture-bred Bluefin tuna is scheduled to begin in October.

The conservation group WWF said wild Southern Bluefin Tuna stocks were in a "perilous state, at less than 10 per cent of its virgin biomass".

It hoped the breeding program might eventually help ease pressure on wild populations, but WWF warned aquaculture operations had their own environmental consequences.

Clean Seas Tuna, the company behind the airlift, said about 30 divers, scientists and aquaculture technicians were involved in the complex operation, with divers working at a depth of up to 40 metres to muster the fish ahead of the trip to shore.

Company chairman Hagen Stehr said the fish that were transferred were carefully selected over a long period of time.

He said the transfer was conducted to ensure an adequate egg supply ahead of the spawning period, while May was considered the optimal time because of the compatibility of ocean and tank-water temperatures.

"We have achieved a major breakthrough in aquaculture technology and we anticipate even better results from our next spawning as a result of what we have learnt and continue to learn about husbandry procedures, diet and fingerling management," Mr Stehr said.

"We have already achieved continuous spawning by our captive Southern Bluefin Tuna broodstock over more than a month and the production of more than 50 million fertilised eggs and 30 million larvae."

Mr Stehr said 90 per cent of the eggs produced were fertilised, producing baby tuna more than 12 centimetres long that could grow to 40kg within three years.

He said Monday's transfer, which involved lowering the fish through the roof of the breeding facility, was an extensive and complex operation.

A temporary air traffic control system was even set up to monitor wind conditions and other aircraft in the area.

But Mr Stehr said the operation was necessary to ensure the company's assets arrived "in great shape" and was completed in perfect conditions.

WWF Australia's fisheries program manager Peter Trott said any advancement that would reduce pressure on wild tuna stocks was welcome.

But he noted aquaculture operations had their own environmental issues, including putting pressure on other fish stocks used to fatten captive fish populations.

"These aquaculture operations ... they come with other associated environmental issues which can result in large footprints in marine ecosystems," he said. "They don't come risk free."

He said WWF was awaiting the latest assessment of Southern Bluefin Tuna stocks, due out later this year.

But he said the last assessment, taken before Japan admitted to a massive under reporting of its tuna take, showed Southern Bluefin was in a "perilous" state.

"Our guess is that this next assessment is also going to be less than 10 per cent of virgin biomass, which is a pretty critical point," he said.