sive closures and openings characterized commer-
cial fishing in these locations. In 1961, commercial
fishing for sturgeon was closed in Manitoba but it
resumed again in 1970, albeit at low levels.
After fisheries in the larger lakes had declined,
smaller northern inland waters became the subject
of commercial interest. Impacts on these popula-
tions are masked by the aggregate reporting of sta-
tistics. For example, in Ontario, commercially har-
vested fish from all northern inland waters (rivers
and lakes) were recorded in one category making it
impossible to trace results from one particular wa-
terbody. This is further exacerbated by incomplete
reporting by commercial fisherman and the rela-
tively low priority that managers place on ensuring
compliance in this fishery. By the late 1980’s, the
combined northern inland harvest in Ontario was
twice that of the Great Lakes (Duckworth et al.1).
Habitat alterationHabitat protection is considered to be the key fac-
tor in the conservation and rehabilitation of the re-
maining lake sturgeon stocks in Ontario (Duck-
worth et al.^1 ).Maintenance and enhancement of ex-
isting lake sturgeon habitat is considered the third
highest priority in Manitoba after the maintenance
of genetic integrity and the protection of existing
stocks (Anonymous^2 ). Lake sturgeon require swift
current and large rough substrate for spawning and
embryo incubation. This dependence on riverine
environments makes them vulnerable to develop-
ment on rivers that alters habitat.
Hydroelectric generation facilities affect both
periodic and seasonal water level fluctuations, caus-
ing decreased production and loss of fish (Payne
1987). Low water conditions after spawning can af-
fect success of embryo survival as embryos experi-(^1) Duckworth, G., T. Mosindy, E. Armstrong, G. Goodchild, G.
Preston, M. Hart & C. Jessop. 1992. Adraft management strategy
for lake sturgeon in Ontario. Edition 6, 31 July 1992. Ministry of
Natural Resources Unpublished Manuscript.
(^2) Anonymous. 1992. A sturgeon management strategy for Mani-
toba: a discussion paper (draft). October 1992. Manitoba Natural
Resources Department, Fisheries Branch Unpublished Manu-
script.
Figure 2.Mitochondrial DNA haplotype frequencies in lake
sturgeon from the Moose River basin, Ontario. Hydroelectric
generating stations are represented by slashes (data from Fergu-
son et al. 1993). Haplotype 1 = black, haplotype 2 = clear.
ence variable water temperatures, low oxygen con-
centrations, and desiccation. Young fish can be-
come trapped in shallow pools and subjected to
heavy mortality through predation, temperature,
and oxygen stress. Adults have become stranded in
shallow pools and mortality occurs when pools be-
come anoxic or freeze (Duckworth et al.^1 ).
Dams also restrict movements of lake sturgeon,
preventing fish from reaching critical habitat such
as spawning sites, and by stranding fish between
barriers. High water conditions associated with
dams can also flood and eliminate rapids and chutes
previously used by spawning fish (Duckworth et
al.^1 ). A population genetics study of lake sturgeon
within the Moose River Basin in northeastern On-
tario suggested that there is significant gene flow
among most sites in the watershed (Ferguson et al.
1993, Figure 2). Dam construction or other artificial