Update on brook trout rehabilitation in the Ontario waters of Lake Superior, Lake Nipigon, and the Nipigon River

Public Workshop Proceedings
Upper Great Lakes Management Unit – Lake Superior Technical Report 11-02 (November 2011)

Executive Summary

Brook trout populations have declined from historic highs in the Ontario waters of Lake Superior, Lake Nipigon, and the Nipigon River. In an effort to enhance populations, a protective sport fishing regulation was applied in 2005, allowing the possession of 1 brook trout greater than 56 cm (22 in) in length. Associated with the new regulation was a public recommendation to review the status of brook trout after a five year period. As a result, in March 2011 the Ontario Ministry of Natural Resources (OMNR) hosted a workshop to present information collected from 2005 to 2010, review the progress of brook trout rehabilitation, and to discuss future actions.

Brook trout populations and fisheries in Lake Nipigon showed substantial change after the sport fishing regulation was amended. Brook trout numbers and average size increased in two Lake Nipigon spawning populations, although numbers remain at a fraction of 1930’s levels. Catch rates of the average angler have improved but remain below management objectives. Declines were observed in the total number of brook trout caught by anglers and also in the proportion of anglers targeting brook trout. However, both measures returned to pre-2005 levels. Catch rates by co-operative anglers exceeded management goals for Lake Nipigon. The proportion of spawning brook trout protected from angler harvest increased by 43% and 59% in two Lake Nipigon populations.

Co-operative anglers in Lake Nipigon and the Nipigon River captured 15% to 33% of tagged brook trout at least twice. High recapture rates reveal the effectiveness of catch and release but also high vulnerability to angling. Catch rates by co-operative anglers generally increased after 2004 in Lake Nipigon, the Nipigon River and Lake Superior. After the new sport fishing regulation was in place brook trout were caught in previously undocumented areas. The proportion of brook trout protected from angler harvest increased by 22% in the Nipigon River and 17% in Nipigon Bay.

Brook trout in Lake Superior are not a unique sub-species and both stream-resident and migratory brook trout occur in the
Nipigon Bay watershed. Movement studies indicate brook trout frequent specific habitats but can move long distances. Similar large scale movements occur in Lake Nipigon.

U.S. efforts to restore Lake Superior brook trout include stocking, habitat improvement, public outreach, and protective angling regulations. Wisconsin and Michigan still allow significant harvest opportunities in streams. Wild brook trout remain rare in most of the American waters of Lake Superior.

Although protective sport fishing regulations have been in place for a short period (five years or approximately one brook trout generation), signs of rehabilitation are encouraging and the current regulation is recommended to remain in place.

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