Frying wild salmon in southwest Sweden
A project to encourage the
return of wild salmon straddling the Norwegian border is beginning to bear
fruit after the implementation of ERDF-funded program.
The main objective of the
project was to identify the needs to save Vänern salmon, and to implement
measures necessary to increase the stocks.
Two activities in the realization of the project:
- The dissemination of information, and the development of close cooperation between Swedish and Norwegian stakeholders.
These measures will be of great
importance for future actions to save the Vänern salmon.
Lake Vänern in southwest
Sweden has been an important fishing ground for over 9000 years.
It is known for its
freshwater salmon isolated from the sea.
This lake, the largest in
the EU, is home to two species of freshwater salmon, both known as Vänern
salmon.
Both breeds are related to
the Baltic salmon and are distinguished by their long spawning migrations and
their large size, some specimens reaching 15kg.
The largest freshwater
salmon ever caught, over 20 kg, was caught in the waters of Lake Vänern.
Declining salmon population
The construction of
several hydroelectric power stations along with the
Klarälven-Trysilelva-Femundselva river system during the 20th century led to a
dramatic salmon decline.
This system straddling the
border between Norway and Sweden, is caused principally decline in the once
abundant salmon population in Lake Vänern.
Dams and power plants
prevented fish from reaching their traditional spawning grounds, while others
died in the power plant turbines.
It is estimated that the
spawning stock of salmon in the lake and river system is now only 5% of its
level at the beginning of the 19th century.
This decline has harmed the
region, which is highly dependent on fishing, fish processing, and fishing
tourism.
Approach to encourage the wild salmon return
Since 1930s, the natural
reproduction of salmon has been maintained by moving fish to spawning grounds
upstream of the first power station using trucks.
However, this is not a
sustainable approach.
Therefore, the ERDF-funded
project "Save the salmon in the lake of Vänern" has developed an
action plan to solve this problem differently.
The project includes the
construction of lifts and bypass channels, allowing young and adult salmon to
bypass the power plants in both directions.
After the lifts and
channels construction, the salmon number returning to the lake each year is expected
to increase from only 1,000 to 3,0000.
Over the next 20 years,
the project also, aims to make the Klarälven-Trysilelva-Femundselva river system
one of the most abundant salmon systems in Scandinavia.
That is to support the
local communities economically.
Salmon in trucks: cope with drought
The US government hopes to
rescue fish from dry rivers and guide them to the Pacific Ocean.
Faced with a chronic
drought, particularly early this year, California has found a way to help its
famous Chinook salmon reach the Pacific Ocean.
Despite rivers with too
little flow or too warm water: transport the fry by road, in tankers.
The California Department
of Fish and Wildlife is learning from the past 15years of salmon releases and drought
to increase the success chances.
- Salmon are migratory
Salmon are born in rivers,
swim to the Pacific when they reach maturity.
They can spend up to seven
years there, but eventually return to their native waters to breed and die.
Trucking young salmon to
downstream release sites has proven to be one.
- The project volume
The operation was launched
in April 2021 and is due to continue until June.
It avoids 80 to 150 km of
rivers where significant mortality has occurred in the past.
In total, nearly 17
million young salmon will be transported by truck from four Californian
hatcheries.
Salman project yield: 20 million eggs
At the end of May, several
dozen of them are already crowding the top of the ladder, ready to be pushed
into a tank at the hatchery.
Where CO2 mixed with the
water anesthetizes the ardour of the fish, the largest of which can exceed 22
kg.
They are marked and given
an injection of vitamin B1 before being released.
In a few months, once the
breeding season has arrived.
The eggs will be extracted
from the females and artificially mixed with the semen of the males to fertilize
them.
Up to 20 million salmon
eggs, placed in trays permanently irrigated with water from the Feather River.
As in their natural
environment will then be stored in the hatchery premises until the fry emerges.
These baby salmon are then
kept in the open air, in screened tanks to avoid being used as food by herons
and other predators.
Until they have reached a
sufficient size to be released into the sea.
Since 10 May, the
Californian authorities have declared a state of drought emergency in more than
40 counties.
Butte County, where the Oroville
Dam is located, is already classified as "exceptional", the highest
level.
The situation, exacerbated
by the effects of climate change across the western US, is not expected to
improve until rainfall returns in 5-6 months.
