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The Atlantic Salmon |
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The Future....? |
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| So what can we do? | The River Guddena |
| The Ranga River | The Delphi |
| Genetic Integrity of the Broodstock | Climate Change |
| The North Atlantic Oscillation | We must arrest the decline |
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I
believe in the twenty first century, The Atlantic Salmon will again become
an asset of major importance to the British Isles. The falling catch
returns plus misguided management of some of our rivers will give way to a
more practically orientated enhancement of the natural stock of salmon.
This in turn, will see the rivers of Great Britain producing again, large
numbers of Salmon. When the fish are in the sea, there is not much we can do, other than supporting the cessation of all forms of netting, but with the knowledge gained over the past 40 years we can maximize smolt production in our rivers. |
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Method
- In recent years many river containing Atlantic Salmon have benefited form the results of restocking. The
River Guddena, in
Denmark adopted a strategy of placing Pre Smolts into imprinting ponds
adjacent to the river, then transferring them via a floating pen 100km to
the sea. They were then released in the outer estuary, well beyond any
potential pollution problem and inshore predators. On their return to the
river, they were then trapped adjacent to the imprinting pond and used for
broodstock. Relatively large numbers can now be seen in the system and their progeny are used to enhance the all-important spawning stock and to provide a recreational fishery. The
Ranga River
[Iceland] has benefited from a similar scheme although in this case the
smolts are released straight into the river from the imprinting ponds. The program started in the mid eighties and has seen the annual rod catch increase from fifty in 1988 to three thousand seven hundred in 2000. The
Delphi in Ireland is
another stocking success story. Once a Sea Trout river, now one of Irelands
most successful recreational salmon fisheries. Method
of Obtaining the broodstock- All of the above can be used for the collection of broodstock on a river system, which has a depleted stock. Breeding from nearly related parents frequently causes deterioration amongst mammals. Reasoning from analogy, [if similar to mammals] should we suppose the infusion of fresh blood would improve fish? [J H Nall] Genetic
Integrity of the Broodstock - Genetic
Integrity is a term frequently used by fishery’s Biologist, when practical
people start talking about restocking salmon rivers. It may be true that the
stock of each river carry a different genetic code. It may also be true to
say that each tributary in a river system has, it’s own specific genetic
code, but in my opinion, we are talking about one of the most adaptable
creatures mother nature has put on this planet, a true survivor. 1.
Does any British river have a true native stock of salmon, which
carry only the genes Mother Nature intended them to have?
No. The reason that I can answer these questions with confidence is
- Restocking
of rivers has taken place for 150 years or more. Since the first restocking
by man, the gene pool of fish in all rivers has, in all probability been
somewhat distorted.
The
sexually mature Parr, the progeny of the male and female spring salmon from
tributary X, is now feeding in
the main stem of the river, seeking out the best feeding area’s. Along
come Mr. and Mrs. Grilse who proceed to make a redd not far from our
precocious friend. As the female Grilse lays her eggs, Mr. Parr nips in and
fertilizes a small, but important number of eggs. So
now there are spring salmon genes from tributary X being crossed with the
genes of Grilse in the main stem of the river. On
the other hand, the same Parr may follow a large autumn salmon into
tributary Y and spread his genes there. The spreading of genes in this way
is one reason salmon have survived as long as they have as it enables them
to adapt to the ever-changing environment around them. Yes
it is true there will be fish that possess a gene pool, which will make them
more tolerant than others, of conditions within a particular tributary, but
with an ever-changing environment, the ambience and habitat within the
tributary will change also. So,
Nature’s little insurance policy ensures a variety of genes exist in each
tributary and in the main stem of the river to provide the back up the
species needs to counteract environmental change. Environmental
factors change over a long and sometimes shorter period of time within a
tributary. A tributary, which is now producing predominantly spring salmon
may have, at one time, produced summer running salmon. As
far as broodstock for the hatchery is concerned, if we were to catch salmon
with the rod and line before the end of April, we would know they were
spring fish and most of them hen fish. These fish should be kept in tanks in
the hatchery and later used for stripping. The planting out of the fed Fry
or Parr, in a tributary known to hold spring stock would ensure natural
selection would take place and the fish best adapted to today’s
particular conditions would thrive. 3.
We also know that some tagged fish have been found in rivers adjacent
to their origin, so there may already be a low element of genetic
crossbreeding, albeit at low numbers. We
are frequently told, when faced with poor runs of fish, that Climate change
at sea is the problem and that there is nothing we can do about it. The
latter may be true. Below is a summary of the reasons that climatic conditions such as we have at the moment, favour Grilse and not Salmon. The
North Atlantic Oscillation North
Atlantic Oscillation plays, in the North Atlantic, a comparable role to the
El Niño Southern Oscillation, on pelagic ecosystems. The
North Atlantic Oscillation (NAO) is an alternation of air mass that occurs
between the subtropical region (centred on the Azores), and the sub-polar
region (centred on Iceland). The state of NAO determines the speed and
direction of the westerlies across the North Atlantic as well as
temperatures on both sides of this ocean, during winter and early spring. A
high NAO pattern is characterized in the northeast Atlantic, by a
reinforcement of the westerlies that are pushed further south, and hence by
warmer winter temperatures than normal. A low NAO pattern is typified by a
weakening of the westerlies, which are moved far north from their average
position, and by colder winter temperatures. During
periods of high NAO, the sea surface temperatures [SST] in the north western
Atlantic cool, the result of which is a slower and less bountiful growth in
Phytoplankton and Zooplankton. On
the other hand with a high NAO, areas such as the North Sea, Norwegian Sea,
Faeroese Plateau and Barents Sea get warmer.
Phytoplankton and Zooplankton in these areas thrive, and a healthy
food chain commences. When
the NAO is low, the above areas cool and the North Western Atlantic warms,
this means that food in the nearer home waters is less plentiful and fish
migrating to the west side of the Atlantic do better. Reading
the above, it will come as no surprise, that over the past 20 years or so
the NAO has been high, the result of which is, our large multi sea winter [MSW]
salmon which traditionally migrate to the west side of the Atlantic to feed,
find food in short supply. This in itself does not account for the general
demise of the salmon. The
chart below shows the NAO highs and lows over the past century.
Particular attention must be arrested to the period from 1950 -1970 when the
index was low over a twenty-year period. Anglers refer to this period,
“the good old days”, when spring salmon were in abundance.
It
is commonly known that Grilse tend, not to migrate to the west side of the
Atlantic, but feed nearer to home, so it follows that, while the east part
of the Atlantic is warm and the NAO high, Grilse will be the dominant
component in our rivers. I
would like to add, that if the NAO index is neither one extreme nor the
other, given no nets or long line fishery, both MSW and Grilse should
thrive. We
still have some rivers, which produce relatively good runs of MSW spring
salmon, the South Esk being one. An explanation for this could be that the
majority of spring fish now migrating from these rivers probably feed on
this side of the Atlantic, if so, then it shows the ability of that strain
of fish to adapt to changing environmental conditions. On
final thing to add is that between 1910 and 1950, forty-eight salmon of over
50lbs were caught in the UK by rod and line. In the last fifty years there
has been only one. During that period [1910-1950] the NAO was more stable
and there was no long period of one extreme or the other. This would suggest
that Salmon did not have to adapt to one or the other and the survival rate
at sea of both Grilse and MSW fish, was high. This can be seen by the study
of Russian rivers. Some hold, predominantly Grilse and some predominantly
Salmon, both of which are thriving. This will be due to good feeding by both
sets of fish. [High Marine Survival] Marine Conditions on this
side of the Atlantic have probably never been better suited for High Marine
Survival amongst Grilse. I
firmly believe, and I am sure I will not be the only one to think this that
the most fundamental problem with our salmon rivers is; not enough smolts are being produced. What
rivers do people talk about in the angling press? They are either rivers;
which have been restocked using hatchery reared fish to provide a surplus to
be caught with rod and line. Or rivers which once had plenty fish and now
have very few. Rivers
which are at the moment doing well [which are a minority] have one thing in
common; they are managed by far sighted dedicated men of whom, sadly, there
are not enough. I
have worked on the Spey over the past 17 years and have spent a considerable
amount of my time studying the river and the fish in it. My earnest hope
for the future is to see a very much larger quantity of Salmon being
produced by, not only this river, but by all UK Rivers. I
am convinced our Salmon fisheries can be improved, and significantly
improved A
very important point here, is the fact that the annual catch in every one of
our rivers should be treated as a harvest, and like all harvests, this
depends on one main factor, whether the seed is sown. If the
seed is not sown then we cannot expect to reap. A
farmer who sowed no seed and expected to reap a field of Oats, Barley. Etc.
would be regarded as a complete lunatic. If
a farmer had only 1000 seeds of barley, would he through them on the ground
and hope for the best? Or would he take care and plant them in the best
possible piece of land, as to ensure maximum production. The answer is
simple! In
the case of salmon however, the final crop depends on the sowing of several
years’ seed. Because we have taken for hundreds of years, it is time to
give back. Good use of hatchery’s WILL (Not -
might] help nature work at its best and provide an insurance policy
which will make it certain, no matter what happens, there will always be
stock left in the sea to perpetuate the species. The
future of our salmon and sea trout rivers will largely depend on how they
are managed today. There is not one single river in the UK, which is
producing the full harvest it is capable of, in fact most are producing less
than one tenth of that figure. This is entirely down to gross mismanagement.
I
am not saying that everyone involved are fools, but to a great extent, when
a fishery manager, scientist moves in one direction, like “feel jock”,
the rest follow. When
years of one type of management is proving no good, it’s time to look at
something else. We must regard our river as a natural treasure, it must be managed so as to provide, food, recreation and economic stability for the community as a whole. Below
is a quote from a book- More Light on Salmon - By R. Murdoch We
must arrest the decline of our Salmon Fisheries, and see henceforth that
their improvement is continuously progressive. We
have side tracked really necessary inquiry and enterprise much to long.
Instead of tackling pressing matters of paramount importance, we have
fiddled over trifles for years, and spent time and money with a grand
prodigality broadcasting theories, which could never by any possibility be
turned to useful account. Fads that must inevitably perish have obsessed us.
We have no constructive work to our credit. Some
commonsense suggestions for the improvement of our Salmon Fisheries are long
overdue and would be hailed as a godsend. “Every
salmon fishery should have a sufficient number of hatcheries, with feeding
ponds and rearing burns attached, managed by alert and practical men” - R
Murdoch Finally I must acknowledge
help on the "North Atlantic
Oscillation" by: |
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