Didymo, ‘’Rock Snot”, has been discovered in the Karamea River, West Coast, South island, New Zealand.
Regarded by many as the jewel in New Zealand’s fishing crown, the Karamea is internationally renowned for it’s fish and scenery. It is also a famed tramping (hiking) track which follows much of the river.
Dept. of Conservation Motueka area manager Martin Rodd said it would impact on the “significant natural values” of the river and would be detrimental to the outstanding recreational fishing the Karamea offered.
“The Karamea-Leslie Track, which runs alongside the river, also is a popular backcountry tramping route.”
If the didymo spread further in the national park it could also affect rivers managed as important habitat for the endangered native whio or blue duck.
The algae was discovered by a fishing guide at a site between Moonstone Lake and Venus Hut.
From October 1st felt-sole wading boots have been banned in NZ because of the suspected link between them and carrying Didymo. But this only toyed with problem. Now that Summer is with us more and more anglers are ‘wading wet’, that is in shorts over athletic tights to cover legs from brambles and biting insects. Trampers wear this gear too, and they cross the river frequently. These tights are at least as effective in carrying Didymo as felt soles.
The other area that must be dealt with quickly is overseas visiting anglers who typically cover a number of rivers in a short space of time, often in helicopters. It cannot be too hard to require all waders and boots to be presented as having been dipped in a disinfecting solution and then completely dried in a dryer, before boarding a helicopter, or four wheel drive. In fact even better would be to require two sets of boots and waders (one could be hired), for use on alternating days.
The cost of failure to comply by the pilot or guide would be revocation of the pilot’s flying license, or banning a Guide from future operations.
That covers anglers, but does not cover a trampers, kayakers and white water rafters. After all DOC believe it was a kayaker that bought Didymo to NZ from overseas.
The very hard answer to the spread of Didymo problem? Ban all use of the affected rivers completely, by all users, unless they can present all clothing and all equipment to inspection stations prior to using the river, and re-present all clothing and equipment on exiting the river, for disinfecting and drying. This equipment not returned until it is completely dry.
The costs? User pays.

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