Interactions Between Farmed and Wild Fish
Interactions between farmed and wild fish
An overview
2
1
Unique challenges in fish
• New species are domesticated at a much more rapid speed – both in numbers and efficiency than ever before in history • Difficult (or impossible) to avoid escapees • When escaped – large areas can be influenced • Often introduction to new areas • Number of individuals farmed can be much larger than in wild population
3
4
2
Two important misconceptions regarding selection
1. That artificial selection as such leads to less genetic variation for important traits Ex:” ..farmed salmon … is breed with less genetic variation …” (Source: www.miljostatus.no)
2. Farmed salmon have other genes or alleles than wild salmon
5
The overall model
Environment 1 Migration Genetic distance Wild salmon population Environment 2
?
Farmed salmon population
6
3
Two different “schools” have coexisted
Inheritance Single genes
Animal breeding
Natural adaptation
Quantitative genetics
Population genetics
Maintenance of genetic resources
7
Two different genetic views
Genetic adaptation
Environments
8
4
Two different genetic views
Genetic adaptation
Environments
9
From single gene models to normal distribution
10
5
11
A more dynamic and realistic ”fitness model”
Wild strain
Farmed strain Distribution of the fitness trait
Nature
Farm
Environment
12
6
Major problems with Norwegian farmed salmon
• In some small rivers, more than 50 % of the migrating fish are of farmed origin • They often come in late in the season ruin the nests of the wild parents • Offspring tends to be more active and faster growing compete for scarce resources
13
14
7
Other treats for the wild salmon populations
• The greatest threats for the wild salmon populations are the regulation of the rivers, mostly due to power plants
– E.g. in the county Hordaland, 23 (out of 57) wild river populations
An overview
2
1
Unique challenges in fish
• New species are domesticated at a much more rapid speed – both in numbers and efficiency than ever before in history • Difficult (or impossible) to avoid escapees • When escaped – large areas can be influenced • Often introduction to new areas • Number of individuals farmed can be much larger than in wild population
3
4
2
Two important misconceptions regarding selection
1. That artificial selection as such leads to less genetic variation for important traits Ex:” ..farmed salmon … is breed with less genetic variation …” (Source: www.miljostatus.no)
2. Farmed salmon have other genes or alleles than wild salmon
5
The overall model
Environment 1 Migration Genetic distance Wild salmon population Environment 2
?
Farmed salmon population
6
3
Two different “schools” have coexisted
Inheritance Single genes
Animal breeding
Natural adaptation
Quantitative genetics
Population genetics
Maintenance of genetic resources
7
Two different genetic views
Genetic adaptation
Environments
8
4
Two different genetic views
Genetic adaptation
Environments
9
From single gene models to normal distribution
10
5
11
A more dynamic and realistic ”fitness model”
Wild strain
Farmed strain Distribution of the fitness trait
Nature
Farm
Environment
12
6
Major problems with Norwegian farmed salmon
• In some small rivers, more than 50 % of the migrating fish are of farmed origin • They often come in late in the season ruin the nests of the wild parents • Offspring tends to be more active and faster growing compete for scarce resources
13
14
7
Other treats for the wild salmon populations
• The greatest threats for the wild salmon populations are the regulation of the rivers, mostly due to power plants
– E.g. in the county Hordaland, 23 (out of 57) wild river populations