Biomanipulation du meunier noir (Catostomus commersoni)

eached maturity, the method used could have caused the observed variations. Those
observed during white sucker mass removal in lakes Claudette and Des Îles could be
attributed to an increase in recruitment. An increase in recruitment induces an increase
in the proportion of smaller mature individuals, which is responsible for a lower mean
length at maturity. After the end of white sucker mass removal, the increase in the mean
length at maturity of brook trout in Lake Claudette could be explained by the increase in
growth of older individuals.
3.5.5 Brook trout reproductive investment
During white sucker mass removal, brook trout females produced a larger number
of eggs but of smaller size compared to the period before the biomanipulation and the
reverse occurred after the cessation of white sucker mass removal (brook trout females
produced a smaller number of eggs but of larger size). Because larger juveniles hatch
from larger eggs, and larger juveniles have a better chance of survival in early life than
do smaller juveniles (Hutchings 1991) these observations suggest that for brook trout,
there is a selection for the production of smaller numbers of eggs but of larger size with
increases in inter-specific competition. The effects of food availability and egg size on
juvenile brook trout survival results in different optimal egg sizes for environments that
differ in food abundance (Hutchings 1991). In a study on Atlantic salmon, it was
suggested that females exhibited phenotypic plasticity in response to the likely feeding
opportunities to be encountered by their offspring (Jons son et al. 1996). Consequently,
in environments where food is readily available, egg size tends to be smaller while the
reverse occurs in environments where food is less abundant. In addition to food supply,
many studies have reported an influence of growth rate on the fecundity of fish. The
production of more offspring was generally found to be advantageous where, due to
higher food availability, juvenile growth rates were higher, whereas larger offspring
were found to be favoured where growth rates were lower (Bagenal 1969; Ware 1975;
Thorpe et al. 1984; Jonsson et al. 1996; Lobon-Cervia et al. 1997). These results suggest
that for brook trout, the changes in intra- and interspecific competition through the white
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