Report of the 2005 ICES/NASCO Symposium on Interactions ...

NINA SPECIAL REPORT 34
has been made to classify <strong>the</strong> fish into different groups, or
escapement events, by using catch per unit effort (catch
per net per day) and size distribution <strong>of</strong> <strong>the</strong> catch from
different geographical sub-regions. In addition, <strong>the</strong>
genotypes <strong>of</strong> some sub-samples are compared. It is
concluded that most <strong>of</strong> <strong>the</strong> escaped farmed fish were <strong>of</strong>
local origin and that catch per unit effort may be a useful
tool for monitoring escape incidents and <strong>the</strong> relative
abundance <strong>of</strong> escaped farmed fish. There were clear
indications <strong>of</strong> a decline in <strong>the</strong> stock <strong>of</strong> escaped rainbow
trout during <strong>the</strong> fishery.
The feeding behaviour features <strong>of</strong> cultured
and wild salmon in Kola Peninsula rivers
Alexander V Orlov,Yuri V Gerasimov and Oleg M Lapshin
In order to investigate <strong>the</strong> behaviour and distribution <strong>of</strong>
young salmon and adaptation <strong>of</strong> cultured fish to <strong>the</strong>
natural environment, an underwater survey was
conducted on <strong>the</strong> Shugor and Luvenga rivers. Behaviour
was examined, current speed measured and drift samples
collected. The food and feeding habits <strong>of</strong> 34 wild and 44
cultured smolts released from <strong>the</strong> Kandalaksha fish
nursery were also studied. The young fish moved freely
over <strong>the</strong> area in all directions, 5 to 10 m away, stopping
every 1 to 2 m. They became somewhat aggressive only
when, on very rare occasions, <strong>the</strong>y moved within 0.3 m <strong>of</strong>
each o<strong>the</strong>r. From about <strong>the</strong> same distance <strong>the</strong> parr
would flee from <strong>the</strong> approaching observer. The young fish
mostly fed in <strong>the</strong> bottom 15 cm <strong>of</strong> <strong>the</strong> water column,
with current speeds <strong>of</strong> 0.2 to 0.35 m/s, making 5 to 10 cm
feeding lunges every 20 seconds. When cultured fish
moved from <strong>the</strong>se areas into areas with higher current
speeds (average speeds <strong>of</strong> 0.5 m/s) and lower drift density
(2.55 species/m 3 ) <strong>the</strong>y did not show a tendency to return
to slower-moving water, unlike wild fish. The smolts fed on
bottom invertebrates carried with <strong>the</strong> current, and insects
which had fallen onto <strong>the</strong> surface <strong>of</strong> <strong>the</strong> water. The
cultured fish had a significantly larger share <strong>of</strong> <strong>the</strong> former
in <strong>the</strong>ir diet (40% and 25% respectively). Few <strong>of</strong> <strong>the</strong> fish
examined had empty stomachs so it may be assumed that
both <strong>the</strong> wild and cultured smolts were feeding actively.
However, on <strong>the</strong> basis <strong>of</strong> <strong>the</strong> average food quantity per
stomach it may be assumed that <strong>the</strong> wild smolts were
feeding more actively than <strong>the</strong> cultured ones.
Invertebrate content in <strong>the</strong> above rivers is 3% <strong>of</strong> <strong>the</strong> total
quantity <strong>of</strong> formed particles, <strong>the</strong> remaining 97% being
exuvium <strong>of</strong> aquatic and terrestrial insects, algae and
various plant remains. Non-feed remains were found in
13% <strong>of</strong> wild and 25% <strong>of</strong> cultured salmon, i.e. <strong>the</strong> cultured
smolts are less capable <strong>of</strong> differentiating food in <strong>the</strong> water,
making more false food lunges (from 20 to 30%) than
wild fish. The cultured fish were more aggressive, in terms
<strong>of</strong> <strong>the</strong> frequency <strong>of</strong> brawls, with individual fish reacting to
each o<strong>the</strong>r from larger distance. Wild smolts would flee
to escape from <strong>the</strong> closing observer, while <strong>the</strong> cultured
fish would allow <strong>the</strong> observer to come closer. The
cultured and wild fish have generally similar diet and
feeding behaviour. Certain differences, however, were
observed in <strong>the</strong> saturation ratio and distance <strong>of</strong> response
to feed, to each o<strong>the</strong>r and to <strong>the</strong> diver.
Physiological and behavioural effects <strong>of</strong>
introgression <strong>of</strong> salmonid fast-growing
domestic genotypes into non-selected
genetic backgrounds
Wendy Tymchuk and Robert H Devlin
Domestication in fish <strong>of</strong>ten involves direct selection for
improved growth rates as well as o<strong>the</strong>r correlated traits,
and can <strong>the</strong>refore have a significant impact on life history.
Many fitness-related traits, such as growth, competitive
ability and anti-predator behaviour, have been found to
have a genetic component. Due to an altered selection
regime, <strong>the</strong> cultured fish may not be as adapted to <strong>the</strong>
natural environment as wild fish. This research
summarizes <strong>the</strong> growth, behaviour and physiology <strong>of</strong> fastgrowing
(domesticated aquaculture), slow-growing (nonselected),
and hybrid (F1, F2 backcross, and F3 backcross)
strains <strong>of</strong> coho salmon (Oncorhynchus kisutch) and
rainbow trout (O. mykiss). Growth <strong>of</strong> <strong>the</strong> strains was
compared under both culture and semi-natural rearing
conditions. Under all environments, <strong>the</strong>re was a strong
correlation between growth and <strong>the</strong> proportion <strong>of</strong>
domestic genes within <strong>the</strong> genotype. Comparisons <strong>of</strong>
anti-predator behaviour and hormone pr<strong>of</strong>iles illustrated
similar trends. Assessment <strong>of</strong> <strong>the</strong> expression <strong>of</strong> fitnessrelated
phenotypes in <strong>the</strong> hybrid strains can provide
information on <strong>the</strong> genetic changes that have evolved
during <strong>the</strong> domestication process. Knowledge <strong>of</strong> <strong>the</strong>
genetic changes responsible for altered growth rates in
fish is crucial information needed to increase our ability to
predict <strong>the</strong> consequences <strong>of</strong> introgression between fastand
slow-growing strains <strong>of</strong> fish.
Genetic history <strong>of</strong> a restoration river, <strong>the</strong>
Connecticut River
Fernando Ayllon, Stephen Gephard, Francis Juanes and Eva
Garcia-Vazquez
The Connecticut River lost its Atlantic salmon population
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