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STURGEON BIOLOGY AND POPULATION HISTORY
IN THE GREAT LAKES
Sturgeon Acipenser fulvescens, inhabit large
river and lake systems primarily in the Mississippi
River, Hudson Bay and Great Lakes basins. It has
and continues to represent an important biological component
of the Great Lakes fish community. By the early
1900's many populations of lake sturgeon throughout
their range had been greatly reduced or extirpated as
a result of overfishing, habitat loss, the construction
of dams, and pollution. Lake sturgeon are listed
as either threatened or endangered by 19 of the 20 states
within its original range in the United States.
This ancient family of fishes has been recognized since
the Upper Cretaceous period (136 million years ago),
at a time when dinosaurs were at the height of their
sturgeon are the only sturgeon species endemic to the
Great Lakes basin and are the largest freshwater fish
indigenous to that system. Lake sturgeon can be
considered a nearshore, warmwater species with water
temperature and depth preferences of low 50s to mid-60oF
and 15-30 feet, respectively. Lake sturgeon are
benthivores, feeding on small invertebrates such as
insect larvae, crayfish, snails, clams, and leeches.
history characteristics of lake sturgeon are unique
with respect to other fishes and are as follows:
maturity in females is reached between 14 and 33
years, most often from 24-26 years; and, 8 to 12
years for males (but may take up to 22 years);
lake sturgeon spawn once every 4 to 9 years while
males spawn every 2 to 7 years;
occurs on clean, gravel shoals and stream rapids
from April to June in preferred water temperatures
lake sturgeon lay 4,000 to 7,000 eggs per pound
rates are quite variable throughout its range and
depend on temperature, food availability, and water
typical life-span of lake sturgeon is 55 years for
males and 80-150 years for females.
a consequence of interrupted spawning cycles, only 10-20%
of adult lake sturgeon within a population are sexually
active and spawn during a given season. Little is known
about seasonal movements of lake sturgeon. Some
adult lake sturgeon have been found to remain in a small
territory during the summer months. While others
have been observed long distances from their original
capture site one year later. Adult sturgeon habitually
return to spawn in streams where they were born (homing
behavior), often migrating long distances up rivers in
the spring. After hatching, some young lake sturgeon
have been observed to remain in their natal rivers for
their first summer of life.
History of the Great Lakes Population
most accurate, yet biased, representation of the history
of Great Lakes lake sturgeon populations is through
the use of commercial harvest data. A summary
of the catch, by era, is discussed below.
Early commercial fisherman (pre-1850) perceived lake
sturgeon as a nuisance fish because of fishing gear
destruction. This led to their wide-spread slaughter.
As the economic importance of this species was
later recognized, a targeted commercial fishery intensified
by the mid- to late-1800s. For example, during
the heavy fishing years from 1879 to 1900, the commercial
catch of lake sturgeon in the Great Lakes averaged over
1,814 metric tons (4 million pounds). In 1885,
a maximum of 4,901 metric tons (8.6 million pounds)
were harvested, of which 2,359 tons (5.2 million pounds)
came from Lake Erie.
1900 to 1986
1900 to the 1970s, little is known about the lake sturgeon
populations, except for their continued decline.
For example, by the late 1900's, 80% of the lake sturgeon
were removed from Lake Erie. Commercial harvest
was reported until 1977, but at very low numbers after
1956. In the late 1970's, Canadian commercial
operations in Lake Erie reported harvests of 1.36 to
2.27 metric tons (3 to 5 thousand pounds); much reduced
from the previous century. In Lake Michigan, commercial
harvest was closed in 1929 after the catch declined
to only 2000 pounds compared to 3.8 million pounds harvested
affecting the decline in lake sturgeon populations include
commercial overexploitation, followed by some degree of
habitat loss and degradation. Also, the reproductive
cycle further complicates recruitment; hence, catalyzing
their dramatic decline.
loss is sure to be a contributing factor to the demise
of lake sturgeon. For example, in all the Great
Lakes, damming of tributaries prevented access to historical
spawning grounds, destruction of spawning areas occurred
via siltation from deforestation, agriculture, and dredging,
and pollution from nutrient and contaminant loads further
hindered reproductive success.
1987 to Present
to the decline, only a remnant population remains today
in most Great Lakes areas. As a result of these
declines, lake sturgeon are: (U.S.) recognized
by the American Fisheries Society as threatened in North
America and, listed as Endangered, Threatened, or Special
Concern in 19 of 20 states throughout its range.
Lake sturgeon are protected in Canadian waters of the
Great Lakes with closed seasons, size limits, creel
limits, and gear restrictions.
interest in the restoration of lake sturgeon has increased
greatly. The fish can serve as an indicator of
ecosystem health and biodiversity, particularly because
of its unique life history characteristics. Also,
with the addition of zebra and quagga mussels, Dreissena
sp., the energy flow is apparently shifting to the benthos.
This could support increases in populations of benthic
feeding fish such as the native lake sturgeon.
have been developed throughout the Great Lakes basin
between natural resource agencies and commercial fishers,
anglers, recreationalists, landowners, and other water
users to report lake sturgeon sightings to their respective
management agency. Some partnerships allow temporary
possession so critical information can be collected
from the specimens.
sturgeon throughout the Great Lakes appear to be on
the rebound. The recent sightings and scientific research
indicate age-class structure within the current populations.
This is a positive sign that natural reproduction is
occurring, particularly with the number of juvenile
sightings. Although populations are believed to be increasing,
they are still impaired with relation to historical
burdens on lake sturgeon are not well known; however,
researchers have documented low hatching success and
high larval deformities in polluted streams in Montreal.
Lake sturgeon in some waters do not seem to accumulate
high contaminate loads while other populations do.
Contaminant loading depends on the quality of the environment
in which the fish live.
by the U.S. Fish and Wildlife Service | Webmaster