New Brunswick's Department of Natural Resources is advising anglers to keep their gear clean, as fishing season could spark the spread of a harmful fresh water algae and cause problems for salmon and trout populations in the region.

Didymo —known as Didymosphenia geminata among biologists, "rock snot" among anglers— is an algae that forms large brown mats on a river or stream bed. It was discovered last year where the Matapedia River in Quebec flows into the Restigouche Riverin northwestern New Brunswick.

The algae blankets stream beds and chokes off sunlight in the water.

Department of Natural Resources fish habitat biologist Kathryn Collet said the algae hasn't been found in New Brunswick water systems, but the department is alerting anglers in the region, because of the danger to fish.

"It's basically a whole food chain effect," Collet said Friday. "That plays into different trout and other fish species that feed on the food chain, and also impacts obviously on other aquatic plants. Anything that lives on the bottom of a stream or requires something from that area."

The thick algae doesn't seem to be native to any one part of the world, Collet said. It has been spotted on Vancouver Island and in New Zealand, where didymo has had a devastating effect on brown trout.

"When people think of algae, normally they think it's very slimy, but the thing with didymo, when you touch it, it's like wet cotton wool," Collet said. "It looks slimy, but actually when you touch it and try to differentiate it from other algaes, it actually has more of a gritty feel to it."

Fishing season began Sunday in southern New Brunswick.

Only takes 1 cell

It only takes one cell of didymo to colonize a new area, Collet said, adding that experts suspect the algae is spread when it clings to boats and fishing gear, and anglers move between fishing areas.

The danger to New Brunswick waters, Collet said, lies in the popularity of water systems such as the Restigouche and Miramichi, which are considered to be the world's finest rivers for Atlantic salmon, with anglers travelling from all over to fish in their waters.

The Department of Natural Resources is preparing a fact sheet on didymo,advising on howto stop the spread, to be distributed on the department's website.

In the meantime, Collet said waders, clothes and other gear should be washed in hot water or a solution using bleach or salt before moving from one stream to another.