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

NINA SPECIAL REPORT 34
restoration programme, genetic variation at five
microsatellite loci was analysed in a collection <strong>of</strong> old scales
(1950-1965) and samples from modern returning adults
(1998-2004), including individuals born in <strong>the</strong> river and in
<strong>the</strong> hatchery. Heterozygosity values and average number
<strong>of</strong> alleles are very similar in modern and old populations.
Populations inhabiting <strong>the</strong> rivers Ulla and Lérez are more
similar nowadays than <strong>the</strong>y were in <strong>the</strong> past. Although
<strong>the</strong> present Ulla and Lérez populations were initially
restored using a stock mix from o<strong>the</strong>r Galician rivers
(including <strong>the</strong> River Ulla), <strong>the</strong>re are genetic differences
between both populations, suggesting some degree <strong>of</strong>
local adaptation and low straying rates.
Distribution and biological characteristics <strong>of</strong>
escaped farmed salmon in a major subarctic
salmon river (River Teno, Finland/Norway)
Eero Niemelä, Jaakko Erkinaro, Jukka-Pekka Vähä, Craig R
Primmer, Sturla Brørs, Esa Hassinen and Maija Länsman
Escaped salmon from Norwegian fish farms in <strong>the</strong> Arctic
Ocean show a wide spatial dispersion in <strong>the</strong> large
subarctic river Teno, nor<strong>the</strong>rnmost Scandinavia, supporting
perhaps <strong>the</strong> largest wild Atlantic salmon stock complex in
<strong>the</strong> world. Farmed salmon were caught throughout <strong>the</strong>
>250km-long main stem and major tributaries during <strong>the</strong>
fishing season (June-August) in 1987-2004 when <strong>the</strong>
proportion <strong>of</strong> escapees in catch varied between 0.08 and
0.53%. However, <strong>the</strong> number <strong>of</strong> escapees increased
towards <strong>the</strong> end <strong>of</strong> <strong>the</strong> fishing season. The proportion <strong>of</strong>
wild 1-5SW salmon caught in August represented 15-25%
<strong>of</strong> <strong>the</strong> total catch, whereas <strong>the</strong> corresponding proportion
for <strong>the</strong> escaped salmon was as high as 69%. Experimental
sampling after <strong>the</strong> season (September-October) has
revealed high proportions <strong>of</strong> escapees, up to 50%. Weight
<strong>of</strong> <strong>the</strong> escaped salmon varied between 2 and 10 kg. Up
to 88% <strong>of</strong> <strong>the</strong> escaped salmon caught in August showed
significant gonad development, and <strong>the</strong>re are also direct
observations <strong>of</strong> escapees on spawning grounds during <strong>the</strong>
breeding season. This reflects high potential for successful
reproduction <strong>of</strong> escaped salmon. Scale analysis indicated
that 4.5% <strong>of</strong> <strong>the</strong> escaped salmon were repeat spawners.
Highly significant genetic differentiation was observed
between wild and escaped farmed salmon captured in <strong>the</strong>
river.
Towards sustainable salmon aquaculture -
zoning <strong>of</strong> <strong>the</strong> Icelandic coastline
Sigurdur Gudjonsson
Over 100 Icelandic rivers foster natural salmon
populations that are considered as important parts <strong>of</strong>
Icelandic nature. Sport fishery <strong>of</strong> Atlantic salmon is very
important for Iceland with annual turnover <strong>of</strong>
approximately 125 million euros. Large fishing companies
show interest in salmon cage rearing. Cage rearing <strong>of</strong>
salmon was tried in Iceland in <strong>the</strong> 1980s and 1990s but
was not successful, as conditions are harsh around Iceland.
Salmon has been farmed in land-based units since <strong>the</strong>
1980s. Interested salmon farmers claim that cage rearing
around Iceland can be successful today because <strong>of</strong> better
salmon strains, better cages and better knowledge. They
have also argued that salmon farming can be important in
Iceland, creating jobs and improving <strong>the</strong> economy in rural
areas. River owners fear that only a few farmed salmon in
<strong>the</strong>ir river can harm <strong>the</strong> image <strong>of</strong> <strong>the</strong>ir pristine river and
salmon. Fur<strong>the</strong>rmore, river owners and environmentalists
fear that salmon cage rearing will threaten <strong>the</strong> valuable
wild stocks, as salmon escapees from <strong>the</strong> cages will
migrate to <strong>the</strong> rivers, cause genetic mixing and breakdown
<strong>of</strong> <strong>the</strong> local adaptation <strong>of</strong> <strong>the</strong> stocks, as well as spreading
parasites and diseases. They fear that eventually it will
leave <strong>the</strong> rivers without salmon, ruining <strong>the</strong>ir income.
Discussion and debate <strong>of</strong> <strong>the</strong>se different views has been
going on in Iceland. Positive and negative sides <strong>of</strong> salmon
farming in o<strong>the</strong>r countries were evaluated. The Icelandic
parliament, Althingi, passed new legislation on fish farming
enabling <strong>the</strong> government to manage fish farming better.
Salmon farming is not allowed in <strong>the</strong> bays and fjords with
<strong>the</strong> most valuable salmon rivers. This was considered as a
step towards sustainable salmon farming and as a
compromise between <strong>the</strong>se opposing views. Salmon
farming is only allowed in certain areas and <strong>the</strong>
experience gained <strong>the</strong>re will be used for fur<strong>the</strong>r
evaluation and development <strong>of</strong> salmon farming in Iceland.
Use <strong>of</strong> catch statistics to monitor <strong>the</strong>
abundance <strong>of</strong> escaped farmed salmon and
rainbow trout in <strong>the</strong> sea in a region <strong>of</strong>
western Norway
Ove T Skilbrei and Vidar Wennevik
Catch statistics and scale samples have been collected
from a gill net fishery targeted for escaped farmed
salmonids (1 October - 28 February) for <strong>the</strong> years 2001 -
2004 in Hordaland County, western Norway. An attempt
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