Biomanipulation du meunier noir (Catostomus commersoni)

to respond to these changes. Although the short-term impacts of biomanipulations have
been evaluated in many studies, long-term surveys were rarely done (Sutherland et al.
2004).
The objective of the present study was to quantify the white sucker and brook trout
responses to 6-9 years of white sucker mass removal in three lakes and to the cessation
of this biomanipulation in two of these lakes. The species responses were determined by
comparing their abundance, biomass, growth and fecundity, before, during and after the
end of mass removals. A third lake, which was still undergoing mass removals at the
time of the study, had not shown strong decreases in white sucker abundances. This lake
was also the object of a comparison with previous results in order to determine if the
important decrease in white sucker abundance observed in recent years has lead to the
expected responses in the white sucker and brook trout populations.
3.3 MATERIALS AND METHODS
3.3.1 Stndy lakes
The biomanipulation experiment took place in 3 lakes located in the province of
Québec (Canada). Lakes Mastigou, Claudette and Des Îles are located in Réserve
Mastigouche (46°34'N, 73°34'W), ZEC (Zone d'exploitation contrôlée) Martin-Valin
(48°40'N, 70 0 37'W) and ZEC des Nymphes (46°28'N, 73°35'W) respectively. The three
lakes are typical oligotrophic temperate lakes (Brodeur et al. 2001) and contain
sympatric brook trout and white sucker populations. Lakes Mastigou and Des Îles also
contained other cyprinid species, but their relative biomass accounted for less than 10%
of total fish biomass before mass removal (Table 1). Brook trout populations of alllakes
are subject to sport fishing and exploitation is carefully controlled by the Québec
government.
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