Death tally after rotenone dose in Miramichi watershed: invasive fish 32, salmon 514

A progress report on the use of rotenone in the Miramichi River watershed to protect Atlantic salmon from an invasive species says the first application killed 32 smallmouth bass, the targeted fish, and 514 salmon, most of them juveniles.

A spokesperson for the group applying the rotenone, however, suggests people not read too much into the lopsided death toll.

The Working Group on Smallmouth Bass Eradication in the Miramichi was required to submit the report to the Department of Fisheries and Oceans as part of its permit to put rotenone — used as an insecticide, and pesticide and piscicide — in the water last fall.

The report, dated Dec. 15, 2022, details the rotenone application on Lake Brook and 15 kilometres of the Southwest Miramichi River on Sept. 8, 2022, which the group calls "phase one." 

Neville Crabbe, the only person allowed to speak for the working group, said there was no expectation that more bass, a predator that feeds on young salmon and salmon resources, would be killed than any other fish. 

"They're an invasive species that are new to that part of the ecosystem, and the numbers really are not significant to any degree," Crabbe said Thursday. "The threat exists if you have four smallmouths or 4,000."

"I think even DFO would tell you the same thing that there's kind of nothing there with the numbers."

When asked if the treatment was successful, Crabbe said yes.

But he added that success for the group will be the full eradication of smallmouth bass from the watershed, including Miramichi Lake, which has not yet been treated with rotenone. 

"And having been prevented to this point from completing our project, we can't achieve that metric of success," Crabbe said.

The working group has been trying to spray Miramichi Lake since summer 2021 but has been blocked by Wolastoqey women paddling on the lake to prevent spraying as well as by legal actions. Cottagers on the lake have spoken out against the spraying, which proponents said would kill all aquatic life, not just the bass.

Crabbe would not say whether a second application would be tried this year, but a "substantial announcement" can be expected soon, after much discussion among group members.

CBC News obtained the progress report from the Department of Fisheries and Oceans through a freedom of information request after Crabbe did not respond to queries during the summer.

DFO spokesperson Paulette Hall said Thursday that as an invasive species, smallmouth bass are not yet prevalent or established, "and that explains why the post-treatment results are much higher for those native fish than for the targeted species of the treatment."