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Currently,
it is estimated that 571 White Sturgeon live within the Nechako
River. This number is very low, contains far too few juvenile
fish, and will not support a healthy, vibrant sturgeon population.
Local biologists and scientists have predicted that within
the next 40-50 years, if the current trend is not reversed,
the Nechako White Sturgeon will be extinct. This means everyone
needs to work together to help save the Nechako White Sturgeon!
Sturgeon
Problems
Sometimes
our activities can alter fish habitat to the point where fish’s
survival or health is threatened.
Human
activities that effect sturgeon habitat are:
- Urban
Development
- Waste
Managmement
- Land
Use - farming, logging
- Road
and Corridor Development
- Regulation
Of River Flow
- Pollution
In
the case of the Nechako River , the development of the Kenney
Dam in the late 1950s, and the subsequent alteration of the
Nechako ’s flows, has likely had a negative effect on the
sturgeon. White sturgeon populations in other regulated systems,
including the Kootenay/Kootenai and Columbia rivers, have
also experienced declines. The effect(s) of river regulation
that impact white sturgeon survivability are not well understood.
Slow
Maturation
The
Nechako white sturgeon are different from the lower and mid
Fraser River sturgeon populations. Nechako sturgeon are slower
to grow and likely slower to mature. Fraser sturgeon mature
and can spawn between the ages of 14 and 20, with males maturing
at an earlier age than females. Once sturgeon reach the age
of sexual maturation, they don’t spawn every year, but may
spawn only 1 in 3-5 or more years, with females spawning less
frequently than males. The late age of maturation and infrequent
repeat spawning will hamper the survivability of Nechako sturgeon
and potentially other sturgeon stocks.
Lack
of Juveniles
The
Nechako white sturgeon population, as can be seen from the
graph above, does not have high numbers of juvenile fish in
the 1 to 25 year old range. By comparision, the combined catches
from the Fraser mainstem stocks indicate these populations
are made up largely of young fish, which should be the case
with any healthy population. The Nechako population seems
to be comprised largely of fish 30 to 50 years of age. It
seems that younger generations of fish are not surviving or
“recruiting” to maturity. The graph below depicts ages of
a sample of sturgeon collected from the early 1980s and a
sample from the late 1990s. It is evident that the population
is ageing with very few new juvenile fish “recruiting” into
the population. This is a dangerous trend.
Age
Distribution Chart
See
enlarged chart
Recruitment
Failure
The failure
of a population to produce juvenile fish at a rate that will
replenish or maintain the adult or reproductive portion of the
population, such as what has occurred in the Nechako white sturgeon
population, is known as a “recruitment failure.” There are a
number of scenarios that could be playing-out to cause a recruitment
failure, but they generally result from an absence of spawning,
unsuccessful spawning, or conditions that result in poor egg,
larval or juvenile survival.
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