Temagami Stewardship Council


To preserve, protect, restore and improve, the natural resources and environment of Lake Temagami & Cross Lake !
Fisheries News
Eradicating Round Goby from Pefferlaw Brook 
An Experimental Operation to Control an Invasive Fish 
by Jane Sirois
In November, MNR's provincial Invasive Species Program and Aurora District, in partnership with the Ontario Federation of Anglers and Hunters (OFAH) and the Department of Fisheries and Oceans (DFO), wrapped up a complex operation to eradicate round goby from the Pefferlaw Brook and keep them from spreading into Lake Simcoe. Because of the confined distribution of the round goby at the doorstep of a very important fishery the partners undertook this serious measure to control an invading fish.
When round gobies were first reported in late July, 2004, MNR launched an intensive monitoring program in Pefferlaw Brook. The monitoring confirmed that although the prolific little fish was spreading gradually downstream it was confined to a stretch of the brook between the dam in the Village of Pefferlaw and the lake five kilometres away. While no one knows how the round goby were introduced it was likely a result of the use and handling of live bait.
Based on the effects seen in the Great Lakes, MNR believed Lake Simcoe's ecosystem could be profoundly altered by an invasion of the round goby. With the advice and support of partners from the University of Windsor, the DFO, and the OFAH, MNR sought specialized technical expertise from Greenlands International Consulting Ltd. on the feasibility of removing the round goby. All options for stopping the advance of the fish were considered, including: barriers, entrapment, using a chemical piscicide containing rotenone and doing nothing.
Ultimately, only two options were available: do nothing or use rotenone, an organic piscicide which targets all gill-breathing species in a waterway. The option to use the piscicide offered the best chances for achieving eradication of round goby. If no action was taken, the biodiversity and ecosystem stability of Lake Simcoe could suffer dramatic consequences. As managers of Ontario's fisheries, MNR chose to make every effort to protect the biodiversity of Lake Simcoe and its multi-million dollar fishery by attempting to eradicate the round goby from Pefferlaw Brook.
Although the round goby were confined within a five-kilometre stretch of the river, several biological, chemical and physical factors had to be considered for successful treatment with rotenone. Lake levels had to be low while stream flow needed to be sufficient to transport the rotenone efficiently. Water temperatures had to be low enough to ensure goby spawning had ceased and all eggs hatched out (because rotenone does not kill fish eggs); yet the water could not be too cold to initiate the round goby's burrowing behaviour which would protect it from a chemical treatment. Burrowing is thought to occur in the fall and persist throughout the winter months.
From early on, planning and preparations focused on a narrow window of opportunity that was expected to open mid- to end of October. In the last week of August, however, round goby were found a kilometre farther downstream. They had jumped ahead faster than anticipated and reached the mouth of the Pefferlaw Brook. This resulted in last minute alterations to the treatment plan to include the more intensive treatment of the river downstream of Highway 48 which involved several additional backwater channels.
Intensive and continuous monitoring in the lake itself and above the dam from the time the goby were first discovered had revealed no sign of round goby. MNR staff decided therefore to move forward as quickly as possible with the plan unless round goby were discovered in Lake Simcoe.
DFO's Sea Lamprey Control Centre agreed to lend its expertise to the initiative providing equipment and numerous staff licensed to apply chemical treatment in aquatic environments. Treatment planning involved sophisticated calculations of water volume and flow, chemical concentrations and time required for an optimal application of the chemical for optimal results. In the meantime, MNR worked around the clock to get a series of necessary approvals from the Ontario Pesticides Advisory Committee, DFO through full Canadian Environmental Assessment Act (CEAA) review and the Ministry of the Environment for a permit under the Pesticides Act. Residents and businesses in the treatment area, elected representatives and the local First Nations community were informed of MNRs intentions and on October 4th a well attended public meeting went ahead in Pefferlaw.
Between October 11th and 14th MNR directed a massive effort to transfer as many non-target fish as possible from that five-kilometre stretch of Pefferlaw Brook out into Lake Simcoe. Over 4,000 game fish alone were collected by electro-fishing with the help of two Shimano Canada Ltd crews operating large live-release boats along with staff and equipment from DFO, OFAH, the Lake Simcoe Region Conservation Authority, the Bait Association of Ontario and volunteers from local angling clubs. An added worry at that time was the possibility that a run of Lake Simcoe's famous yellow perch or the seasonal migration of emerald shiners into Pefferlaw Brook could occur before the treatment began.
Final approvals to proceed with the chemical application arrived 24 hours before the treatment was scheduled to begin.
The treatment was carried out in two stages over three days. On Tuesday, October 18th a small fleet of boats criss-crossed the slow moving waters of the brook downstream of the bridge on Highway 48 applying rotenone to all navigable areas including large and small marinas and private boat slips right up to the mouth of Pefferlaw Brook including the area around the breakwall. Other boats followed close behind to collect fish killed by the chemical. Ironically, the targets of this operation, the round goby, have no swim bladder and most sank to the bottom out of sight. Some goby, however, were washed onto shore and collected for disposal.
The following day, the Sea Lamprey Program staff continued on foot to treat those areas too shallow to be reached by boat. On Thursday, DFO installed a drip line station across the dam in Pefferlaw Village and, the river flow, as calculated, carried the chemical downstream to the bridge to complete the treatment.
In the end, a total of 4.8 metric tons of fish was collected during and after the treatment of which approximately 95 per cent were common carp and shiner species.
MNR will continue to monitor the recolonization of the Pefferlaw Brook. Jason Borwick, Aurora District management biologist and coordinator of the operation reported in November that the system was already showing signs the fish community had begun recolonizing the treated area as predicted. Fish were caught at both the river mouth and just below the dam.
How soon will we know whether the goal of eradicating round goby from Pefferlaw Brook was achieved? To date, all indications are that the project was successful but it will take another field season to determine the critical success of the initiative.
Was it worth the huge effort to undertake this controversial step?
There are no guarantees the project will ultimately protect Lake Simcoe from the goby invasion, said Jason. However, we know that, had we done nothing, goby would be in Lake Simcoe next year. This was the first major round goby removal project of its kind in North America, he added, and this ground-breaking experiment clearly shows our commitment to being as proactive as possible in the effort to combat invasive species.
Beth Brownson, the Invasive Species program's senior introduction biologist and policy coordinator for the Pefferlaw Brook project points out that public outreach and education must continue as important tools in the effort to control the round goby and other invasive species. She acknowledges too how important the Pefferlaw Brook goby project is in meeting Ontario's commitments to the National Aquatic Invasive Species plan. The national plan stresses an urgent need to build capacity for early detection, rapid response, management and eradication of invasives like the round goby, and those lessons learned at Pefferlaw will provide a foundation to build on.
The Pefferlaw Brook project was fully supported by the organization and by the OFAH. The core project team included, from MNR, Beth Brownson, Christine Villegas, Jason Borwick, Wil Wegman, Jane Sirois, Laurie Uetz, Shawn Verge and Peter Waring; Francine Macdonald from OFAH, and from DFO, Nick Mandrak, Melanie Boivin and Brian Stephens.
Numerous MNR staff from every division generously pitched in to make this operation work by driving boats, lending equipment, collecting fish, checking traps, fast-tracking internal approvals and through countless other ways. Many thanks to all of them.
A last hurrah goes to the volunteers from the OFAH, local fish and game clubs, Johnston Riverside Restaurant and Marina, the Bait Association of Ontario and staff from the Lake Simcoe Region Conservation Authority Association and our partners, the Ontario Federation of Anglers and Hunters and the Department of Fisheries and Oceans. It couldn't have happened without them.
Post Script As part of MOEs conditions for a permit under the Pesticides Act, MNR was required to sample both surface and well water for the presence of rotenone before the treatment, one day after the treatment and again two weeks after. Due to public concern, samples were also analyzed for the presence of volatile organic compounds (VOCs). Results of this sampling confirmed there was no migration of rotenone into groundwater, that rotenone was almost completely detoxified one day after the treatment, and that no significant increase in VOCs had occurred.