Spawning Brook Trout

Brook trout spawn in the fall over areas of groundwater upwelling on the Nipigon River.

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Brook trout spawn in the fall over areas of groundwater upwelling on the Nipigon River. They require high quality cold water environments for survival and reproduction. Brook trout spawning areas in the Nipigon River have been impacted by the regulation of the river for power generation. Forgan Lake, created by the Pine Portage dam, flooded the best brook trout waters of the river, including Virgin Falls. Numerous other factors affect brook trout spawning include: competition for spawning beds by introduced Pacific Salmon; eggs that are highly susceptible to siltation; scouring from log drives; and the impacts of gravel extraction on areas of groundwater upwelling (Swainson 2001a).

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Roving angler surveys were conducted sporadically on the river between 1987 and 1994 and volunteer angler diary programs have been in place since 1988. Brook trout fishing quality has varied from one fish per 20 hours of fishing in 1987 to one fish per 7-8 hours in 1994 and has stayed at this average ever since. Tagging and tracking studies have also provided information about brook trout movements and migration patterns. Some brook trout have been caught and released as many as three times in the same location. Brook trout tagged in the Lower River have been recovered as far away as Rossport and in the Gravel River area. In 1989 and 1990, brook trout in Jessie Lake and the lower Nipigon River were implanted with radio and sonic transmitters and tracked to locate their spawning beds. Field studies from 1988 to 1990 demonstrated that fluctuating water levels, caused by hydroelectric dam operations, exposed up to 90% (21 of 23) of the identified brook trout redds in the Nipigon River causing desiccation and freezing during the spawning and incubation period.

In response to public demand to save the Nipigon brook trout, as part of the Nipigon District Fisheries Management Plan 1989- 2000, a detailed restoration plan was developed and implemented in 1989. Flow tests were conducted to determine minimum requirements to allow spawning and to protect brook trout redds during the incubation period. Spawning habitat was created by constructing two artificial upwelling areas by piping and dispersing groundwater up through gravel in the Nipigon River. In addition, a large area (1000 m2) and several small (1.5 m2) areas where groundwater discharged through unsuitable substrate were improved by replacing or covering the native bottom material with suitable gravel materials. To provide additional spawning and nursery habitat, a small groundwater fed tributary was reshaped and resurfaced with gravel substrate. Nursery habitat was also enhanced in a nearby, small groundwater fed tributary by excavating a 31 m2 pool. To provide access for spawning fish and to avoid stranding during rapid drawdown events caused by hydro-electric dam operations, the littoral zone was recontoured near a natural spawning area and near the habitat enhancement projects.

Since the establishment of the flow agreement a maximum of 20% of the identified brook trout redds have been exposed to desiccation and freezing. Through a public consultation process directed by the Remedial Action Plan for the Nipigon Bay, the 1990 interim flow agreement was expanded in 1994 to a Watershed Management Plan for the Nipigon River and Lake Nipigon and from this a Nipigon River Operating Plan was developed in 1999. The plan gives first priority to protecting brook trout habitat while considering the needs of other stakeholders.

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