Salmon Stocking An International Point of View Ted Potter

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Salmon Stocking An International Point of
ViewTed Potter

• Colloquium on Atlantic salmon
• Atlantic Salmon for Better Management of
  Habitats
• and Salmon-Farms for Restocking
• 21-22 October 2009, Oloron-Stainte-Marie

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Salmon stocking in the North Atlantic

• 40,000,000
• eggs per year taken
• from wild salmon

The aim of stocking is to make better use of
these eggs by rearing them artificially
Based on ICES Working Group on North Atlantic
salmon 2000
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Experiences of stocking in Europe

• Has stocking worked?
• Has it done harm?
• What is the international advice?

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Many reasons and methods

• Green eggs
• Eyed eggs
• Fry
• O parr
• 1 parr
• Smolts

• Mitigation
• Compensating for a problem that cannot be
  removed
• Restoration
• Assisting the recovery of a stock after a
  problem has been removed
• Enhancement
• Supplementing a stock when production is less
  than the potential
• Ranching
• Releasing fish with the intention of catching
  the majority of the returns

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• Some examples

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Restoration stocking
River Thames

• Salmon lost gt150 years ago
• gt 20 years restoration stocking
• No sustained recovery
• Why?

Major changes to river over past 200yrs
Little suitable salmon habitat
Much habitat still of poor quality
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Mitigation stocking
River Tyne
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Salmon rod catch
River Tyne

• Historic catches were good
• But marked decline in 1920s
• Due to pollution in the estuary

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Mitigation stocking
Kielder reservoir - built in 1970s
River Tyne
Mitigation stocking Annual av. 210,000 0
parr 91,000 1 parr
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Salmon rod catch
River Tyne
?
But was it the result of the stocking?
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Salmon rod catch
River Tyne
?
Stocking began
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What did stocking contribute?
River Tyne
Tagging of released parr
Main contribution was restoration
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What caused the improvements?
River Tyne
Stocking
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River Tyne
Improved estuary water quality
Stocking
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River Tyne
Reduced coastal fishing
Improved estuary water quality
Stocking
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Enhancement stocking
Widely used but difficult to assess

• Few programmes have been well monitored
• Many studies fail to assess overall
  effectiveness and impacts

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Enhancement stocking

• Competition

Hatchery fish
Wild fish
?
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Enhancement stocking

• Predation

Wales Cormorants seen to congregate at release
sites
32 tags from one cormorant pellet !
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Distant water fisheries
Coastal nets

• Man is also a predator !

Angling
Estuary nets
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Diseases and parasites
Norway Gyrodactilus salaris Introduced and
spread by stocking

Spain Aeromonas salmonicida Introduced with
Scottish eggs
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Genetic effects

• Experimental studies in Ireland

• Loss of local adaptations
• Growth rate
• Age of smolting
• Smolt run timing
• Maturation age
• Adult run timing
• etc
• Loss of heterogeneity

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Is stocking effective?

• Survival of reared fish is higher in hatchery
  BUT lower after release
• So stocking can produce more fish IF habitat
  connectivity and quality are adequate
• But the benefits are often small

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Is stocking effective?

• And you need to consider
• lost wild production caused by removing
  broodstock
• effects of hatchery releases on wild fish
• quality the reared fish compared with wild fish
• and the risks

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What is the international advice?

• Stocking guidelines ICES, EIFAC, etc

• NASCO -Williamsburg Resolution

• National reports on implementation by end of 2009

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NASCO advice

• All stocking activities should be regulated

• Stocking should be part of an overall management
  plan for the river/stock
• Proposers should set clear objectives and
  time-scales

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NASCO advice

• Address the problems
• habitat
• obstructions
• pollution
• fisheries
• etc

• before stocking

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NASCO advice

• Assess and minimise the risks
• conduct health inspections
• seek expert genetic advice
• evaluate risks to the ecosystem
• minimise the effects of the hatchery rearing

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NASCO advice

• Monitor the results
• contribution to catches
• contribution to spawning
• impacts on wild populations

• If the objectives are not being met STOP
  and review your plan!

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Merci
Et bonne chance avec le restauration de votre
saumon!