Date of Award


Degree Type


Degree Name

Doctor of Philosophy


A northern anadromous population of brook trout (Salvelinus fontinalis), from the Sutton river, in the Ontario Hudson Bay Lowlands, was examined to determine if its life history differed from that reported for the species elsewhere. The Sutton River population was similar to historical anadromous populations native to North America 200 years ago. Only minor differences were discernible between the life histories of brook trout from Sutton River, Ontario, Nelson-Hayes River, Manitoba, and Richmond Gulf, Quebec. All of these populations differed from populations in Canadian Maritime Provinces, in that the northern trout migrated to saline water earlier, matured later and at a larger size. They also had greater longevity and life time fecundities.;These differences in life history were interpreted in light of resource allocation models developed for other anadromous salmonids and the peculiarities of the southwest coast of Hudson Bay.;A comparison of the suitability of scales, fin ray sections and otoliths as ageing structures was undertaken. Scales were the least reliable and accurate due to problems of resorption that were aggravated by the trout's anadromous habits. Fin ray sections and otoliths were of similar accuracy and reliability.;In spite of low marine temperatures, immature trout grew 3.3 cm/month. This exceeds reported growth estimates for anadromous brook trout. The fast growth rate was the result of abundant forage and a sustained production of growth hormone (GH) while resident in the isosmotic waters of Hudson Bay. Sustained GH production also caused reductions of the weight on length regression slope. Slopes stabilized with sexual maturity; mature trout spent less time in the Bay and had slower growth rates.;The blood of trout returning from Hudson Bay did not coagulate. Even minor injuries (e.g., those caused by angling or tagging) resulted in death. This phenomenon was temporary, and may have been induced by the same enzymes responsible for the rapid degradation of GH on re-entry of fresh water. The lack of coagulative ability has profound consequences for the catch and release fishery of the area. As a result the legislation enacted to regulate and protect the fishery is being changed.



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