New Brunswick scientists are on the lookout for an invasion by a tiny river plant that is threatening the wild Atlantic salmon habitat in eastern Quebec.

The plant forms can clog rocky river bottoms with mats of brown goo. The algae's actual name is Didymosphenia geminata — didymo for short — but anglers know it by the more descriptive "rock snot."

An angler casts his line into the Restigouche River in this undated file photo. Scientists are warning those travelling between Quebec and New Brunswick rivers to clean their gear carefully before fishing.
(CBC)

The Restigouche River forms part of the border between New Brunswick and Quebec, which means it's vulnerable to an invasion from upstream in Quebec's Matapedia River, where the algae turned up last year.

Peter Cronin, the manager of fisheries programs for the New Brunswick Department of Natural Resources, says didymo likes clear, pristine waters, like those of the Restigouche in northern New Brunswick, considered to be one of the world's finest rivers for Atlantic salmon.

Cronin says it's only a matter of time before didymo makes its way into New Brunswick's crystal-clear waters. "In those environments it becomes very, very active, forming large colonies, matting the substrates and matting the bottom of the river, and just blanketing stream beds and river beds," he said.

Scientists say the invasive algae didymo is attracted to the clear, rocky river bottoms common in northwestern New Brunswick.
(CBC)

In British Columbia, didymo invaded in the 1990s and has become a nuisance species in certain rivers. Researchers there think it may be proliferating because of increased ultraviolet radiation, caused by a thinning of the ozone layer. Since that invasion, the algae has spread to parts of the United States and New Zealand. 

Cleaning fishing equipment crucial

Scientist Fred Whoriskey works with the Atlantic Salmon Federation, an international salmon conservation group based in St. Andrews, N.B. He says the algae could reduce habitat and food sources for young salmon and trout.

"It's going to affect the invertebrates which affects fish production. It could stop oxygen movement from the surface waters down into gravel areas where eggs of salmonids incubate," he said.

In New Brunswick, officials are hoping that it may not be able to survive cold winter temperatures, even though it's done just fine next door in Quebec's Gaspé.

Cronin says didymo travels easily by attaching itself to hipwaders and fishing gear, and he's working with the governments of Ottawa and Quebec to get the word out to anglers and guides to clean their gear before casting into the Restigouche. 

"We need to get the message out to those people who are spending time on the river. And the way we're going to do that is put a high profile in our angling summary. It'll be on our web page. We're going to put posters up in our camps along the Restigouche, the lodges — the private lodges along the Restigouche will be a source of information to the anglers."