James Foster

Times & Transcript Staff

19 Jun 2012 11:46PM

The last year of a three-year effort to get rid of a non-native species of fish from a lake which is part of the headwaters of the sensitive Miramichi River system is underway.

But whether there will be a fourth straight year of efforts to get every last smallmouth bass out of Miramichi Lake — or whether a fourth year of work will even be necessary — remains an open question.

“This year, at the end of the year we’re going to evaluate our results and there will be a discussion,” says Ghislain Chouinard, regional director of science for the Department of Fisheries and Oceans.

The Miramichi River is one of the most productive nurseries for the troubled Atlantic salmon in the world. Alarm bells went off when it was found in 2008 that Miramichi Lake, which is part of the river system’s headwaters, hosted a spawning population of smallmouth bass, quite likely transplanted there illegally by human hands.

Smallmouth bass are voracious eaters, vicious protectors of their territory and they compete with other species for food and space, so for the past three years the DFO and Miramichi river groups have been striving to eliminate every last smallmouth bass from the lake — all 223 hectares of it, which is a significant undertaking.

They feel they’re making progress, with fewer fish caught with each passing year, in particular markedly fewer fish of spawning age.

Crews are using nets and electrofishing to eradicate the bass, including a boat that can electrofish a large area of water in a shorter time when compared with electrofishing with back packs. Electrofishing stuns the fish so the bass can be removed without harming other species of fish.

A barrier net contains the fish inside the lake and periodic electrofishing of Lake Brook, the only outlet stream from the lake into the Miramichi River system, is conducted to look for escapees.

They’re even angling for smallmouths in a bid to remove as many as possible, and some workers have taken to swim gear and snorkels as part of the effort.

“We need to use different methods to cover the whole lake,” Chouinard says.

The effort has not been without controversy. With the sports salmon fishery worth about $25 million per year to the Miramichi River area, the pressure is great to protect the salmon at all costs.

Some are calling for the entire lake to be poisoned with a chemical that does not harm the lake’s habitat but which destroys all fish, after which stocks of the lake’s native fish which were saved from the lake before the chemicals were applied to it would be returned to their natural habitat to repopulate the body of water. This method has been used often in other areas but it is expensive and requires much work to get the proper permits from Environment Canada.

Many in the fishing community believe it is the only way to be certain to get rid of the bass, but those opposed to the idea say it is uncertain whether the chemical, Rotenone, would be effective on such a large lake.

Meanwhile, the results of the current removal methods are showing promise. Chouinard notes that in eight weeks of work so far at the lake, only two fish have been caught and the catch rate is on a steady decline since the effort began on a large scale back in 2010.

Miramichi Lake is home to a community of 16 species of fish and is a major spawning site for gaspereau (alewife) with approximately 25,000 adults migrating there each spring to spawn, resulting in one to two million juvenile gaspereau leaving the lake nursery in fall.

These fish are now being carried by workers into the lake on their way upstream, and will later be carried out of the lake when it’s time for them to return downstream.