Extent of whirling disease unknown

Press, 28 August 1980, Page 11

Extent of whirling disease unknown

Parliamentary report The full implications of the discovery of whirling disease in young rainbow trout held at the Silverstream hatchery, near Kaiapoi, in February are causing some problems for the Ministry of Agriculture and Fisheries. In its annual report to Parliament, the Ministry said the discovery would create some problems for the salmon enhancement and ocean ranching programmes, and the full implications of the discovery were still being evaluated. Should exports prove feasible, it was clear that certification procedures would have, to be developed to satisfy importing countries.

■ Although quinnat salmon and brown trout could become infected they generally were resistent to the disease. The disease could cause heavy deaths among rainbow trout in hatcheries. In the wild the disease was reported to have little effect. It was known to have been present in the southern part of the South Island since 1971. The Ministry said pressj'e of other work had precluded the surveys needed to deterriiine its full extent. The induced run programme was continuing at Silverstream. In 1979, 333 salmon had returned compared with 68 in 1978, and it was expected that the 1980 run would be much greater.