|04-19-2000 05:51 PM|
Euro studies on CNR
Does catching and releasing salmon harm the fish ?
The research, carried out here and in USA and Canada has come to the
conclusion that salmon caught on rod and line and handled carefully in the
release recover fully in a short time and survive to spawn normally.
Here are references to some recent studies.
Dee, with a large voluntary release programme in place since 1995 has
reported No evidence that there is a problem of survival. ( Work carried out by
John Webb, Marine Laboratory Aberdeen, Research Biologist of the Atlantic
Salmon Trust). In this experiment, salmon were caught by angling (fly) and
then radio tagged. They were subsequently recovered upstream 69-120 days
later. There was 100% survival of this sample after tagging. No damage was
reported on the these fish.
On the Ponoi in Russia, which catches and releases over 8,000 salmon in a
year, the resident fisheries officer (Dr F G Whoriskey of the Atlantic Salmon
Federation) carried out specific research relating to survival of released fish.
62 rod-caught salmon were penned for 24 hours. Only one fish died. (That fish
was heavily scarred by gill net marks). It is interesting that the Russian
government simply did not accept the catch and release results coming out of
North America and asked for new research. The research was to be practical,
in which regular salmon fishers would catch salmon in normal everyday
fishing. These fish were to be landed and have radio tracking pods inserted
into their abdomens. They were then held for twenty four hours, since it is in
this period that any fish likely to succumb to being caught and operated on as
we describe. The salmon were released and tracked. Most of the fish were
identified as followed until the end of the season. Two of these fish were
caught again by anglers and successfully released.
One of these fish was lost track of, possibly because of a malfunction of the
radio pod, since this would locate even a dead salmon. The high survival rate
of these fish provides excellent , recent data in support of catch and release
as a conservation method.
It is interesting that salmon caught by rod and line and then fitted with internal
radio tracking pods either by insertion of the pod via the mouth or by operation
and suture, recover rapidly and live to spawn. The stresses suffered by being
caught and released in normal fishing and being returned properly to the river
are far less than those arising during an experiment involving an operation. A
full account of the Ponoi catch and release programme is included in Wild
River Science, by Fred and Philip Lee, in Atlantic Salmon Journal Autumn,
1997, p 26 et seq.
Other extensive work on catch and release has been carried out by Professor
Bruce Tufts and river authorities in Canada. They worked on the famous
Miramichi in New Brunswick - one of the most renowned salmon waters in the
world. This research, together with other similar work carried out by Professor
Tufts established that salmon returned to the water after being caught by
anglers both survived and spawned well.
In a NASCO ( North Atlantic Salmon Conservation Organisation) consultative
paper on catch and release (CNL9431), noting wide use of catch and release
throughout the salmon world, mortality of released fish in Iceland was shown
to be in the order of 2 - 4%. On the Restigouche system in Canada survival
rates were taken as in the order of 90% (or better). Conclusion: There is
evidence...that catch and release has minimal impact on survival of the fish or
on their reproduction.
What effect has catch and release had on fish
We have not yet had the minimum five years necessary for a salmon cycle
from spawning to returning adults to take place. There is interesting evidence
form the Dee, however. The Girnock Burn, a main spring spawning tributary
where returning females are trapped and studied, reported that in 1995 out of
41 female spawners, eight had been caught and released. The threshold of
that spawning stream is 40 female spawners.
During the winter of 1997, when angling was used by the river board to collect
spawning females, a high percentage of the fish caught for the hatchery had
been caught and released. Clearly, the marginal case is the important one.
Without catch and release specific stocks are in danger of falling below their
threshold of viability.
In related studies on salmonids we can show that spawning capability is not
reduced by releasing rod-caught fish. It therefore is a policy well within the
precautionary principle of salmon conservation in the face of seriously
declining numbers to release salmon of all classes to spawn. Of course there
is an act of faith in this, which only future numbers will prove. In the
meantime, returning salmon voluntarily is a personal contribution fishers can
make. It is an act firmly on the side of the angels.