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Help prevent spread of aquatic weeds & pests
Nov 25, 2004
Author: Northland Regional Council

Biosecurity experts are urging Northlanders to take a closer look at their recreational gear - including nets, wetsuits and boat trailers – to ensure it is not accidentally spreading unwanted aquatic weeds.

Northland Regional Council Biosecurity Team member Lisa Maria says with longer days and warmer weather upon us, people are spending more time fishing, swimming and playing in the region’s lakes and rivers.
“However, while we are having fun in the sun we may inadvertently be polluting the water with aquatic weeds. It’s very easy for water weeds to be spread from one lake or river to another and even the smallest weed fragment snagged on fishing gear or on a boat can be enough to start a new infestation.”

Ms Maria says Northland is fortunate to still have some weed-free pristine lakes.
”Elsewhere in New Zealand aquatic weeds such as oxygen weed have become so dense that it has made it difficult and unpleasant for swimming, boating, and fishing.”

However, Ms Maria says recreational equipment can also spread pests other than weeds.
“Pest fish eggs can often hitchhike a ride amongst fragments of weed clinging to a boat or net. Unfortunately these fish are not the sort that you would want to throw in the frying pan. Fish such as rudd and perch have been released expressly for sport and are not very pleasant on the palate.”

Ms Maria says the aggressive nature and rapid population growth of these pest fish can also ruin good fishing spots.

She says while large infestations of weeds and pest fish may be a nuisance for humans, the unwanted species can have a deadly impact on the native inhabitants of lakes and rivers.
“Native plants and animals, found only in New Zealand and sometimes only in a few lakes, are under threat from being smothered by weeds or eaten by introduced pests.”

Ms Maria says simply checking recreational gear for weeds and removing any found before getting taking to the water can help prevent unwanted distribution of pest species.

She says nets, wetsuits, boat trailers and even the family dog should be checked.

“It only takes a minute or two but can literally make a huge difference to the future of our lakes and rivers.”