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Salmon FARM KEEN to expand N Bob Hickman with the first butterfish larvae produced at Mahanga Bay perform in the hatchery. Fish retained in captivity, along with wild-caught fi sh, were stripped of eggs and sperm in order to investigate butterfi sh egg development and larvae performance. Pre-spawning assessments of wild fi sh indicated they were sexually mature when as small as 300g. Viable eggs were obtained from laboratory-conditioned fi sh weighing just over 500g. Stripping wild fi sh yielded eggs of varying quality. The smallest volume but highest quality of eggs were derived from fi sh stripped immediately after they were captured. In all, around 180,000 fertile eggs were collected, producing around 3500 larvae at fi rst feeding. Wild butterfi sh don't eat seaweed until they are well over 100mm long. Larval fi sh were therefore fi rst reared on live feed and then weaned onto artifi cial diets after 87 days. Around 1500 fi sh made it through the weaning process. After weaning, their growth rate on commercial larval diets appeared to be a little better than the estimated rate for wild butterfi sh, with juvenile fi sh reaching around 100mm long after 300 days of culture. Juveniles appeared to be just as picky as adult fi sh when it came to food choice, eating few of the pellets offered to them, and well over 70 percent of the expensive weaning diet went to waste. What do these trials mean in terms of the potential for farming butterfi sh? Philip Heath, NIWA's principal scientist of aquaculture and fi sheries enhancement says, disappointingly, butterfi sh do not seem to be a viable aquaculture product from either a biological or an economical perspective. "With butterfi sh being endemic to New Zealand, we thought we might be uniquely placed to develop this fi sh as a viable farmed product that doesn't require a fi shmeal diet. Sadly, there's no silver bullet here. "They were certainly easy to capture and proved to be fairly robust fi sh in culture, despite the sea lice infestations. But their slow growth rate, highly selective feeding habits and early sexual maturation tell us butterfi sh are probably not an ideal candidate for commercial culture. It's a disappointing conclusion, but the only one we can draw." Contact Phil Heath at p.heath@niwa.co.nz or phone (04) 380-7987. ew Zealand King Salmon is seeking to double production to 15,000 tonnes by 2015 and expand its processing plant in Nelson to meet international demand for its products. The company has applied to the Environmental Protection Authority for planning permission. It would take about 15 months for the authority to determine if, where and how a new salmon farm would operate in the Marlborough Sounds, says the chief executive offi cer of NZKS, Grant Rosewarne. The project is likely to create around 70 jobs in Marlborough, but the company needed to fi nd environmentally sustainable water space for at least eight new farms to meet demand. The total amount of space involved would still be very small, Rosewarne said. The Marlborough Sounds covers 150,000ha, of which 2800ha is used for mussels. NZ King Salmon currently has fi ve hectares for raising salmon and is seeking a further 10ha of surface water space. The expansion would create about 100 more jobs. "Few agricultural industries have the ability to create such signifi cant export income from such a small amount of space, with a low, localised environmental impact," says Rosewarne. "A scientifi c team, including Cawthron, is studying our present site and improving our understanding of the sounds. We are consulting with a number of people in the community. Everyone will be able to submit evidence in the EPA process." The company has been identifying sustainable sites to raise premium salmon in areas acceptable to other users. "We have invested millions of dollars and been highly successful in developing lucrative specialty markets overseas, which is great for us and great for the country." King salmon require cool temperatures, deep water and good tidal fl ows, he said. Suitable new sites in the Marlborough Sounds needed detailed research. "The environment and visual impact of the farms are two key areas of concern to the Marlborough community and we are well aware of that," says Rosewarne. He has been working on new business plans since taking over as chief executive six months ago. The company is also planning a $16 million expansion of its Nelson processing plant and is seeking to buy property neighbouring its Bullen Street site in Tahunanui as soon as possible. Rosewarne said it would probably double the company's manufacturing capacity. "We do need to do a lot more with automation." The company is already one of Nelson's biggest businesses, employing about 435 staff. The expansion would create additional jobs but not large numbers, because there were effi ciencies to be gained, he said. Export orders for NZ King Salmon's products skyrocketed when fl ight restrictions caused by a volcanic eruption in Iceland prevented people from buying salmon from their traditional overseas suppliers. Rosewarne said the sales continued after the restrictions were lifted. "I think that's because people really like our product." SEPTEMBER/OCTOBER 2011 ■ NZ AQUACULTURE ■ 13