Snapper Aquaculture

Plant and Food Research in Nelson has kept native fin fish species for the past 20+ years including snapper, the commercially and recreationally most important species for northern New Zealand waters. At their purpose-built seafood research facility at the Maitai, the breeding programme is now aimed at doubling the growth rate in captivity to make the commercial case for aquaculture (fish farming). Related species to snapper are in commercial aquaculture elsewhere in the world.

P&F has been breeding and rearing fin fish species for more than decade, with a view to aquaculture in the future, because New Zealand has only three species in aquaculture – green-lipped mussels, Pacific oysters and King salmon. New species need considerable time and funding, so a Crown Research Institute is the appropriate place. P&F has a long history of culturing a variety of commercially important finfish species and it also has trevally under way at Nelson. NIWA Bream Bay also has two fin fish species under way – NZ yellowtail kingfish, and hapuku. The research institutes try to remove the risks around aquaculture operators trying something new.

Previous work at Maitai before the employment of Maren Wellenreuther as senior scientist was on the ideal conditions for holding fin fish, how they could spawn, optimum conditions for rearing baby fish and so on. Her PhD was on evolutionary ecology of fin fish, bringing new tools like genetics informed selective breeding methods/technologies to the P&F fin fish programme.

The NZ snapper (Pagrus auratus) is an extremely hardy fish that has adapted well to breeding in captivity, Wellenreuther said. Spawning happens in groups several times during spring and summer.

Spawning in captivity has produced a surplus of larvae every year – much more than needed for research work. Therefore P&F makes ocean releases of fingerlings every year to enhance the fisheries around Tasman Bay. “Having all these fish enables us to conduct a lot of basic and applied research,” she said. vThe amount of fertilised eggs collected on one good day during the four-month season would be enough for all the research uses during the year – but spawning occurs many more days during the season. “The holding and rearing of snapper is not a production bottleneck. If they are domesticated and you have closed the life cycle, and you produce sufficient larvae, then that is a very good basis for aquaculture.” The snapper broodstock at Nelson is around 70 individuals and probably not all of them are contributing on a daily basis.

Growing times are heavily dependent on temperature and are generally three to four years to reach the minimum legal size – greater than 250 mm in length. But growth rates at present appear to be the greatest challenge to aquaculture, so P&F is focused on trying to boost the growth rates. Broodstock produce larvae of varying size, so there is potential for selection of faster growing lines.

Also Japan has been commercially farming red sea bream and has more than doubled the growth rate, showing that it can be done in a related species.

Food conversion rate also promises to be good, and potentially better than commercial sea-cage grown King salmon.

Snapper tend to slow down in winter and eat very little while in summer they feed voraciously.

The snapper in the Nelson facility are fed on imported extruded pellets and also get crushed up mussels and a moist diet that incorporates fish and supplements. They are probably better fed than in the wild.

Wellenreuther has a five-year MBIE funding project focused on trevally as well as snapper, which is progressing well. Although not so highly valued in NZ, trevally is bred in captivity and commercially grown in sea-cages in Japan (for sashimi) and in the Canary Islands. P&F has a trevally broodstock and first generation fingerlings and established good traits for breeding successfully. The general knowledge gained during the MBIE programme will be applied to other fin fish species in future.

New technology should aid breeding selection but every generation takes three years to sexually mature, which means that progress on breeding better growth rates will take five to 10 years.