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| | River Conservation
Restoration of Salmon and Sea Trout in the Applecross River
In keeping with most rivers in the North West Highlands, the numbers of
adult salmon and sea trout returning to the Applecross River dropped
dramatically during the 1990’s to near extinction levels. Several
factors are likely to have contributed to the decline including climate
change, affecting both the marine and freshwater environments, over
exploitation particularly when migrating smolts are caught as part of a
by-catch, increasing predator numbers, food supply and sea lice
infestations on smolts. The net effect was that, with so few adult fish
spawning successfully in the river, the production of juveniles and
subsequently the numbers of smolts leaving the river was severely
depleted.
To increase the numbers of migrating smolts and thereby
have a chance of restoring runs of adult salmon and sea trout to the
river within a reasonable time-scale, it was obviously necessary to
replace the lost juveniles in the river. With the co-operation of the
Applecross Trust, the Seafield Centre at Kishorn devised and implemented
a restoration programme for the river involving stocking with
significant numbers of young fish. While many rivers use captured wild
fish as broodstock for stocking programmes, this was not an option for
the Applecross River since only a few adults were returning to the
river. Therefore, to generate the numbers of juveniles required to make a
difference, a captive broodstock for both sea trout and salmon had to
be established. This was instigated in 1995 and 1996 respectively, by
retaining some of the eggs stripped from the few wild fish and rearing
them through to maturity in captivity. This eventually resulted in large
numbers of eggs being produced from humble beginnings.
With eggs
from the captive broodstocks coming on-stream towards the end of the
90’s, significant numbers of both salmon and sea trout have been
introduced to the river each year. The young fish are stocked out
throughout the river at various stages and at different times of the
year. Early fry go out in June, larger fry and parr in late summer and
some are taken through to the smolt stage before being released from a
specially constructed release pond towards the lower end of the river.
These smolts are held in the pond for only 3 weeks (for imprinting)
before being released after which they migrate to the sea almost
immediately.
The effect of the restoration programme has been
two-fold. The primary objective was to increase the number of returning
adults. This has been achieved to some extent with rod catches showing a
significant increase in recent years. This has made it possible to
catch up a number of hens and cocks at the end of each season to bring
in “new blood” to the Broodstock. The second effect is on the
biodiversity of the Applecross catchment. The health of a river is
largely judged by the level of young stock within it and many species,
including saw-billed ducks and otters, require good fish numbers for
their survival. In this respect, the stocking programme has benefited
more than just the anglers. |
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