Farm hoping to breed gamefish

By ANNE BESTON

How do you take a wild gamefish and farm it?

A $2.5 million aquaculture venture at Bream Bay, 30km south of Whangarei on the east coast, aims to find out.

The National Institute of Water and Atmospheric Research facility was opened yesterday by Fisheries Minister Pete Hodgson and will initially breed millions of snapper, eels, oysters and mussels.

But high on its list of possible farmed finfish is yellowtail kingfish, a prime target of recreational fishers in northern New Zealand waters.

There is no quota for kingfish in New Zealand, and commercial catches are seasonal and small.

Niwa aquaculture business development manager Dr Simon Hooker said Japan produced about 140,000 tones of farmed kingfish a year from five species, including two hybrids.

Bream Bay will use Japanese technology and expertise.

"There is the opportunity to adapt and refine some of the Japanese techniques, but first we need to know more about the breeding biology and early development of our kingfish species," Dr Hooker said.

In the past 18 months, Niwa and its partner in the kingfish project, Moana Pacific Fisheries, have collected wild kingfish to establish a breeding stock of 20 fish.

They are held in hatcheries at Moana's Pah Farm snapper hatchery on Kawau Island.

Fertilised eggs from wild kingfish will also be used to study how kingfish eggs can be fertilised in captivity and form the basis of captive broodstock.

But experiments so far have highlighted the problems of egg development in captivity.

Experiments so far involved injecting eggs with hormones to promote egg ripening and ovulation but resulted in high failure rates.

Of 147,000 eggs stripped from one wild female fish, 60 per cent developed abnormally and, after 40 days, just 36 survived, all with some form of jaw deformity.

But the growth of the fish was remarkable, said Niwa's aquaculture project manager, Dr Carolyn Poortenaar. Successfully reared fish grew to 3kg in 12 months, and that was expected to increase rapidly once rearing techniques improved.

How the fish adapt to captivity will be an important part of the project. Stress levels in kingfish can be estimated by measuring the levels of a hormone called cortisol. The hormone is released into the fish's blood during stressful periods.

Wild fish captured, confined and transported showed significantly elevated levels, even after 50 hours in holding tanks.

But Dr Poortenaar said the two-year kingfish project, partly financed by the Foundation for Research, Science and Technology, held exciting possibilities for the future of finfish aquaculture in New Zealand.

Other species that might be bred at Bream Bay include seahorses, rock lobsters and groper.

Bream Bay, which obtained resource consent last year before the Government's two-year moratorium on new aquaculture projects, will use huge salt-water tanks to rear hatchlings.

The largest tank holds up to 90,000 litres of water and filters process 150,000 litres of water an hour.

The facility, which covers 3000sq m, uses pipelines from the old Marsden power station to draw seawater.

National Institute of Water and Atmospheric Research

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