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

Abstract

Tolerance to naturally acidic conditions of a Côte-Nord brook trout (Salvelinus fontinalis) strain (Arseneault strain, presumed acid tolerant) does not appear completely genetically mediated, since this tolerance was not evident when the fish were subject to acid conditions of anthropogenic origin. Three wild brook trout strains, at the egg and fingerling stages, were exposed in the field to waters acidified by atmospheric deposition of anthropogenic origin as well as to natural waters typical of the region. Although egg mortality was significantly higher in acid (61.0-85.6%) than in reference (6.3-20.8%) conditions, no differences between strains were noted. Residual density 1 year after stocking with fingerlings was significantly higher (by 56%) in the reference lake than in the acid lake, but differences between strains did not follow any clear tendency. While overall growth was greater in the acid environment, weight yield was lower except for the Arseneault strain. Variations pertaining to gonadosomatic index and percent mature individuals in both males and females seemed linked more to differences in growth than to chemical conditions. Developing a permanent reintroduction program with the Arseneault strain to counter losses of brook trout populations due to acid precipitation in Québec does not appear justified at this time.