Distinguishing Features
The White Sturgeon is the largest
North American sturgeon and probably the largest fish found in the
fresh waters of Canada (Scott and Crossman, 1973). They may reach
a maximum length of 20 feet (6.10m) and weigh up to 1800 pounds,
although the largest authentic record is 1387 pounds and most weigh
considerably less.
Distribution
Columbia Basin: Found in the mainstems
of the Columbia and Kootenay Rivers, and in Kootenay, Arrow, Slocan
and Duncan lakes. Prior to dam construction, they were found in
the upper Columbia River, Trout Lake and Lake Revelstoke (Cannings
and Ptolemy, 1998).
British Columbia: Within the remainder
of B.C. they are found in the main Fraser, Nechako, and the Stuart
rivers, and in some of the lower portions of larger tributaries
of the Fraser such as the Bowron, McGregor and Harrison rivers.
There are unconfirmed reports from the Kettle River, Christina Lake
and the Kennedy and Cowichan rivers on Vancouver Island.
Global: Restricted to the Pacific
watersheds of North America from the Aleutian Islands of Alaska
to Monterey, California.
Habitat
White Sturgeon normally inhabit
large, cool rivers or streams, although several populations are
either restricted to large lakes or spend considerable time there.
They tend to prefer deeper water
in winter than in summer. For spawning purposes they seem to require
deep fast rapids, which may explain recruitment failures under regulated
(dammed) water regimes.
Threats
Habitat alteration by hydroelectric
dams and dyking is probably the greatest threat to the survival
of white sturgeon in British Columbia. Dams have not only flooded
spawning grounds and cut off migration routes, but also reduce flows
while reservoirs are filled during the spring freshet. (Cannings
and Ptolemy, 1998). Chemical contaminants may also have a deleterious
effect on the survival and reproduction of white sturgeon.
Biology
White Sturgeon can live to be over 100 years old.
Long-lived fish such as the sturgeon tend to concentrate chemical
contaminants such as copper, zinc and heavy metals. They tend to
be inactive during the winter, spending their time in deeper water.
Spawning occurs in spring in conjunction with elevated flows (Cannings
and Ptolemy, 1998).
