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In The Field

They survived the winter

After an illegal introduction more than ten years ago, invasive smallmouth bass are spreading in the Miramichi watershed. Field work is now underway to support a major First Nations & NGO led eradication campaign planned for Fall 2020.

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This landmark, known as the ice bridge, on the Southwest Miramichi is the likely starting point for the campaign to eradicate invasive smallmouth bass from the Miramichi watershed. Neville Crabbe/ASF
UPDATE from June 15: Fisheries and Oceans Canada informed the project partners today that a decision on the application to eradicate smallmouth bass from the Miramichi watershed is still pending the completion of the department’s duty to consult First Nations. A final decision is unlikely to come this week as the blog indicates below.

Last week ASF’s New Brunswick program director Nathan Wilbur and I launched a canoe at what’s known as the ice bridge on the Southwest Miramichi River.

It’s an important landmark, because the ice bridge is the likely starting point of a million-dollar program to eradicate smallmouth bass from the Miramichi watershed. These aquatic invaders were illegally introduced to Miramichi Lake sometime prior to 2008, and the first bass was caught in the Southwest Miramichi last August.

Our goal on this trip was to catch and kill any smallmouth we could and map the springs and brooks entering the river between the ice bridge and Moose Call Camp about 15 kilometers downstream, the current end point of the eradication project.

Unfortunately, we were successful on both fronts.

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A map showing the proposed area that will be treated with a rotenone product to eradicate smallmouth bass from the Miramichi watershed. Nathan Wilbur/ASF


When the coronavirus shut down life and shut people in, the Working Group on Smallmouth Bass Eradication in the Miramichi pushed on with the tools of remote work. The project was at a crucial stage and no delay could be afforded.

The discovery of smallmouth in the Southwest Miramichi compelled us to amend the application to eradicate that was submitted to DFO last year, and the department’s review was on hold waiting for new information, including answers to a couple rounds of questions from the regulator and an outline of the plan to use rotenone in the river.

Originally the scope of the project included Miramichi Lake, home to the only known established population of smallmouth in the watershed, and its outlet, Lake Brook, where bass have slipped past DFO’s barrier and been found periodically over the years.

With the help of experts and input from the project partners, on April 8th, 2020, the amended application to eradicate smallmouth bass from the Miramichi watershed was submitted to DFO and New Brunswick’s Department of Environment and Local Government.

Hitting send set up a push to the finish line for one of the one of largest direct conservation actions in New Brunswick history and the only known rotenone treatment we know of being led by First Nations organizations and NGOs, not public governments

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The mouth of Lake Brook which connects Miramichi Lake and the Southwest Miramichi River. Smallmouth bass have slipped past a seasonal barrier operated by DFO at the head of the brook and travelled downstream into the river. Neville Crabbe/ASF


The plan to treat Miramichi Lake and Lake Brook is well formed, but between the discovery of smallmouth in the Southwest Miramichi last August and ice-up, there was not enough time to gather all the details needed for a successful eradication.

This includes measuring, and observing every spring, brook, and trickle enters the river between the ice bridge and Moose Call Camp. During treatment, a rotenone drip station needs to be set up wherever freshwater flows in or fish will find refuge.

We used an incredibly accurate wet areas map generated by Nathan Wilbur and pushed from bank to bank all the way down, stopping wherever the map told us and every time it was right, even where the water coming in was equal to the flow of a garden hose.

Another major task completed last week was securing functional access to strategic points along this relatively remote stretch of the river. Eradication will require pumps, steel drums, generators, batteries, and boats which can’t be easily carried through thick brush.

The landowner on both banks of the treatment area is J.D. Irving Limited. After getting a request from Working Group members for help, the company and its employees set to work cutting trails and building a boat launch into McKiel Pond Pool, a 300-meter slow-flowing deep section where smallmouth seem to be concentrated.

These are two significant items checked off the pre-treatment list. We still need data on water flows, chemistry and tree cover – because direct sunlight degrades rotenone quickly – but most of that information will be collected closer to go-time in order to be accurate.

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A flagged and cleared trail leading to the Southwest Miramichi River inside J.D. Irving's Deersdale forestry district. The company directed crews to work on providing access to strategic locations after getting a request from Working Group members. Nathan Wilbur/ASF


All the way down, in every pocket, pool, and bogan where a smallmouth bass could hide, Nathan and I tried to entice a bite. DFO has approved Section 52 licenses for the project partners making it legal to use spinning gear.

We tried worms, spinners, crankbaits, spinnerbaits, soft plastics, even some top water for show. At the mouth of Lake Brook where the river slows down and gets deep we pulled in chub after chub, and even some yellow perch, but no bass. In McKiel Bogan, a long finger of dead water where earlier sampling indicated smallmouth bass were present, we saw no signs of any fish.

At McKiel Pond Pool, where 24 smallmouth bass were removed by angling last year, we got a hit. On a bright pink Rapala I quickly jerked a tiny smallmouth bass to shore. We estimated it was two-plus years old.

Nathan and I continued to fish hard, adding to our impressive total of chub and perch. We even hooked a few small brook trout, but saw no other bass that first day on the water.

We continually scanned for signs of smallmouth spawning and found none, a good sign. At twilight we pushed on to the landing at Moose Call camp where our truck was parked, loaded up and looped back to the mouth of McKeil Brook for the night.

The next morning we joined senior biologist Chris Connell and Abbey Greer from New Brunswick’s Department of Natural Resources and Energy Development and focused angling on McKeil Pond Pool. We eventually hooked one more small bass and spotted at least four others.

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These two smallmouth bass, the first of 2020 caught in the Southwest Miramichi River were kept and sent to DFO's Gulf Fisheries Centre in Moncton for analysis. Nathan Wilbur/ASF
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Neville Crabbe in the McKiel Brook area on 4 June 2020, exploring for the presence of invasive smallmouth bass. Nathan Wilbur/ASF


Mechanical controls like angling, electrofishing, and netting will continue at Miramichi Lake, in Lake Brook, and the Southwest Miramichi River. Keeping constant lethal pressure on the invasive smallmouth may reduce the chances of successful spawning and stymie their dispersal throughout the system.

DFO is ready to begin a new round of environmental DNA testing in the Southwest Miramichi, covering a huge area from just below Juniper to Boisetown. Analyzing water samples with high-throughput genetic sequencing technology can detect DNA cast off in feces, mucus, and skin cells and revel the species of origin.

These tests, expected to be carried out later this months, will help define the limits of smallmouth bass in the river and will influence final eradication planning.

Most importantly, a decade of advocacy and years of working through the regulatory process is about to come to a head. Next week DFO is expected to provide the project partners an answer on the application to eradicate, a decision that will shape the future of of an entire ecosystem.

To learn more about this project and the use of rotenone in fisheries management visit

Neville Crabbe is executive director of communication with the Atlantic Salmon Federation, a member of the Working Group on Smallmouth Bass Eradication in the Miramichi. He can be reached at

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The Southwest Miramichi at midnight near the mouth of McKiel Brook. Neville Crabbe/ASF