Most carp thought recaptured

Press, 3 May 1984, Page 25

Most carp thought recaptured

PA Hamilton As many as 90 per cent of the Chinese grass carp, which escaped earlier this year into the Waikato River from a drainage area used for a weed control experiment, may have been recaptured, according to one estimate. The Aka Aka-Otaua Drainage Board deputychairman, Mr Sandy Muir, told the Waikato Valley Authority that the estimate came from the fisherman who had caught 10 of the 27 grass carp known to have been caught in the wild.

He said the fisherman told him that the grass carp had been very easily caught, either in Lake Whangape or a small area of the lower Waikato, and the catches had stopped quite suddenly.

From this he had deduced that as many as 90 per cent of the escaped carp had been caught. Hundreds of grass carp in a 2km drain escaped into a 22km section of drains in the Aka Aka-Otaua Drainage District, west of

Pukekohe, earlier this year. Catches in the Waikato River showed that some had also escaped past screens between the drains and the river.

The grass carp were part of an experiment on biological control of weeds in the drains, to see if the fish could be an alternative to mechanical and chemical control. Mr Muir also told fellow authority members that the experiments were continuing in some areas of the district, especially in the Mangawhero drain system. There, 16 big grass carp were keeping a Ikm drain completely free of weeds.

This area had not been affected by the escapes, nor by the decision to suspend the Aka Aka experiment for at least 10 months because of the escapes.

That decision was made because the Ministry of Agriculture and Fisheries does not expect to have more young grass carp big enough to release into the drains again until early next year.