Frequently
Asked Questions on the status
and consequnces of listing White Sturgeon
(PDF 130KB)
Introduction
The white sturgeon is a unique freshwater fish species
that plays a significant role in British Columbia's
cultural and social heritage, as well as our economy.
The white sturgeon (Acipenser transmontanus)
belongs to the sturgeon family Acipenseridae. Not only
is it the largest sturgeon species in North America,
it is also the largest freshwater fish species in North
America. The only other sturgeon species found in British
Columbia waters is the green sturgeon (Acipenser
medirostris Ayres). However, very little is known
about this species except that it tends to be found
under more marine and coastal conditions.
Distribution
White Sturgeon are found in 3 major drainages on the
west coast of North America including the Sacramento
(in California), Columbia (in British Columbia, Idaho
and Washington) and Fraser systems. In British Columbia,
spawning populations of white sturgeon occur in three
rivers: the Fraser/Nechako, Columbia and Kootenay. White
sturgeon have also been observed in the mouth of the
Cowichan and Somass rivers on Vancouver Island. However,
it is likely that these fish represent stray fish from
the mainland systems, possibly the Columbia River in
Washington, rather than separate spawning populations.
Appearance
It is difficult to mistake white sturgeon for other
species (except close sturgeon relatives). These large
fish have been known to grow up to 6 metres long (the
length of a small school bus) and over 600 kg. The overall
body form is long and cylindrical, usually ranging in
colour from greenish grey on the dorsal (back) side
to light grey or white on the ventral (belly) side.
The body is covered with large armour-like scutes
(bony plates) rather than scales like other fishes.
The nose or rostrum of white sturgeon is flattened.
On the underside of the rostrum just in front of
the mouth are four barbels or fleshy whisker-like
projections that are used as sensory organs to detect
food since the water is often murky at the bottom
of the river.
Most of the skeleton is made up largely of cartilage
rather than bone, and the overall appearance is quite
prehistoric, which makes sense since sturgeon have remained
virtually unchanged since they first appeared in the
fossil record 175 million years ago.
Some variation in colour and morphology
(body shape) has been observed in white sturgeon
in B.C. For example, snout length differs markedly
in the Fraser - short nosed and long-nosed fish
are both common.
Life History
One trait that makes the white sturgeon so unusual
is its incredibly long lifespan. Some individuals are
over 100 years old - these individuals were around even
before British Columbia became part of Canada. Given
their long life, they tend to grow slowly and are not
ready to spawn until the females are over 18 years of
age and males are at least 14 years of age. Unlike many
salmon species that spawn once and die, white sturgeon
are capable of spawning many times throughout their
life.
White sturgeon depend on a number of environmental
cues in the spring to spawn - these include water temperature, day length, strength of water current and riverbed material.
Adult sturgeon do not build nests but rather the male
and female release sperm and eggs together in the water
current - called broadcast spawning. A female may release
between 100,000 to 3 million eggs but only a small number
may actually get fertilized. Once they are fertilized,
the eggs become sticky and attach to the river bottom
as soon as they come into contact with it. The young
embryos mature into larvae in 8-15 days and then spend
another 20-30 days nestled in the river bed until they
metamorphose into free- swimming young sturgeon.
Habitat
Tracking studies indicate that sturgeon generally
don't move more than a few km during the summer feeding
season. However,before spawning or when traveling to
over-wintering locations, sturgeon can migrate over
100 km. Adult fish tend to occur in deeper, faster waters
of large river mainstems, where they spend most of their
time on or near the bottom of the riverbed. Juveniles
prefer slow moving sloughs and backwaters. Spawning
habitat is usually in turbulent fast water, but locations
can range from shallow murky side channels with pebbly
and sandy bottoms to deeper, less murky main channels
with larger boulders and cobble.
Feeding
The body shape and mouth structure of white sturgeon is
ideally suited to bottom feeding. Although sturgeon
have poor eyesight, they use their highly sensitive
barbels to locate prey. Rather than using teeth, sturgeon
have a extendible mouth which they can use like a vacuum
cleaner to suck up prey.
Small sturgeon feed on chironomids, as well insect
larvae, molluscs and other small invertebrates. Larger
sturgeon switch to a fish-based diet although chironomids
can still make up a significant part of the diet. White
sturgeon in the Fraser are known to follow sockeye runs
and also feed on eulachon, sculpins and stickleback.
Many of the threats to white sturgeon are specific
to the river system in which they live. In general,
these threats include over-fishing, hydro-electric dams
and associated flow regulation, water diversions and
dyking for flood control and irrigation, introduced
species including predators and competitors, reduced
water quality associated with various land-use practices
(e.g. forestry) and loss of habitat from dredging, gravel
mining and other industries.
Status
In 1990, the white sturgeon was classified by the
Committee on the Status of Endangered Wildlife in Canada
(COSEWIC) as a Species of Special Concern,
but this national designation is overdue for review.
The BC Conservation Data Centre (CDC) has subsequently
reviewed the status of white sturgeon in British Columbia
and has provincially listed it as imperiled
(the second highest 'at-risk' rating), putting it on
BC's red list. Three populations (Nechako,
upper Columbia and Kootenay) were given the highest
possible ranking of critically imperiled. The
Kootenay population, which is a trans-boundary population
shared with Idaho and Montana, has been listed as
endangered
under the US Endangered Species Act (1994).
Since 1995 we have added greatly to our
understanding of white sturgeon biology and habitat
requirements. Unfortunately, these studies have
confirmed that the
Nechako, upper Columbia and Kootenay populations are
declining drastically as a result of recruitment failure.
This means that these populations are not replacing
themselves, either due to unsuccessful spawning or poor
survival of the young. Without conservation action these
populations will likely go extinct.
Recovery Planning
The development of a recovery plan for the Kootenay
sturgeon was led by the US Fish and Wildlife Service
with the assistance of both federal and provincial biologists
from British Columbia. The plan is being implemented
on both sides of the border. Currently, the provincial
Fisheries Program has initiated recovery planning processes
for both the Nechako and upper Columbia populations.
These planning processes will involve representatives
from all levels of government, First Nations and stakeholders
with the overall objective of restoring healthy, self–sustaining
populations to each watershed.
The purpose of recovery plans is to stabilize the remaining
population(s) and prevent further declines and extinction,
and ultimately, to rebuild the population(s) to a healthy,
self–sustaining state. To date, the provincial white
sturgeon recovery plans have been made up of 2 components:
(1) a long–term goal to identify and address the reason(s)
for decline and restore the population to a self–sustaining
state; and, (2) an interim goal to preserve the remaining
gene pool and prevent further loss to the population
through conservation fish culture.
Provincial Programs
Increasingly, fish species are being identified at
being at some risk of extinction. Conservation and recovery
programs must be developed in a strategic and focused
manner because significant cost and effort is often
required to protect and recover threatened or endangered
species.
In British Columbia, the Provincial Fisheries Program
is responsible of the management and conservation of
anadromous (sea–run) trout and freshwater fish species.
Furthermore, under the Accord for the Protection of Species at Risk (signed
in 1995), the province committed to undertake a variety
of actions to identify, protect and develop recovery
plans for species at risk. The federal Species
at Risk Act (SARA) would make many of the commitments
made under the Accord a legal requirement.
To address concerns regarding the status of white sturgeon
in British Columbia, the Fisheries Program has established
a number of river–specific programs. These programs
are designed to increase our knowledge of white sturgeon
biology and habitat requirements in order to better
protect this unique species. These programs include:
Fraser River White Sturgeon
Program
Nechako
River White Sturgeon Program
Columbia White Sturgeon
Program
Other information:
Provincial Species
at Risk brochure
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