(English) Comparison of growth rates for native and hatchery-stocked populations of Esox masquinongy in Nogies Creek, Ontario

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Recent techniques have contributed to a more accurate determination of age by the scale method and a new growth curve for the maskinonge in Nogies Creek has been constructed. Hatchery fish, planted as fingerlings, show similar growth for 4 summers after which their growth rate rapidly falls away from that for the native fish. The hatchery fish require 3 years more than the native fish to reach legal length. A reduction in the annual growth increment for tagged fish ranges from 25% (age IV) to 80% (age VI) of that attained by untagged fish. No significant divergence in the length–weight relationship was observed in the slower growing hatchery fish.