In situ survival and growth of three brook trout (Salvelinus fontinalis) strains subjected to acid conditions of anthropogenic origin at the egg and fingerling stages

Tolerance to naturally acidic conditions of a Cote-Nord brook trout (Salvel inus fontinalis) strain (Arseneault strain, presumed acid tolerant) does no t appear completely genetically mediated, since this tolerance was not evid ent when the fish were subject to acid conditions of anthropogenic origin. Three wild brook trout strains, at the egg and fingerling stages, were expo sed in the field to waters acidified by atmospheric deposition of anthropog enic origin as well as to natural waters typical of the region. Although eg g mortality was significantly higher in acid (61.0-85.6%) than in reference (6.3-20.8%) conditions, no differences between strains were noted. Residua l density 1 year after stocking with fingerlings was significantly higher ( by 56%) in the reference lake than in the acid lake, but differences betwee n strains did not follow any clear tendency. While overall growth was great er in the acid environment, weight yield was lower except for the Arseneaul t strain. Variations pertaining to gonadosomatic index and percent mature i ndividuals in both males and females seemed linked more to differences in g rowth than to chemical conditions. Developing a permanent reintroduction pr ogram with the Arseneault strain to counter losses of brook trout populatio ns due to acid precipitation in Quebec does not appear justified at this ti me.