What we have noted as the arguments for artificial stocking of salmon in the Wye and Usk:

  • If there is sufficient adult stock along with uncommitted and unlimited funds, sites that are inaccessible to wild fish or where wild fish spawning is impossible could be stocked and overall salmon numbers thereby increased. This situation may not exist on the Wye.
  • Mitigation is required because there has been permanent habitat loss from impoundments (reservoirs such as the Elan Valley on the Wye).
  • Carefully selected and consistently good quality aquaculture can, in limited circumstances, achieve juvenile fish densities that are consistent with those achieved in the wild even if at a significantly greater cost than wild production.
  • It can make good 'population bottlenecks'. For example, shortage of spawning gravels, or egg mortality.
  • Understanding the hatchery process requires no particular education, knowledge of fisheries, or concept of other issues - it a default assumption that there will be more fish in the river as a result.
  • Stocking provides some with a "feel good factor".

And the arguments against stocking for the Wye and Usk:

  • It is very expensive. Year on year costs need to be met and if the stocking process stops, the river reverts to its previous level without necessarily achieving any expansion of stock. The pre-existing problems remain.
  • Stocking is limited by the areas suitable for planting out fish and availability of broodstock.
  • Stocking is frequently at the expense of permanent improvements.
  • The long-term assessment of results of historic stocking the Wye and Usk (NRA 1993) are extremely poor.
  • When salmon stocks are below their conservation target and there are barriers that could be opened or water quality issues, there is evidence to show that artificial rearing is the worst option.
  • Broodstock is taken at the expense of wild spawning and this reduction to wild spawning is never allowed for in calculations of effectiveness of stocking.
  • The survival rate post release of reared fish is substantially lower than that of wild fish.
  • Hatcheries are prone to catastrophes, often resulting in an overall net loss to the river. These inevitable events seldom receive the full glare of publicity.
  • There are dangers of mixing the genetics of fish whose unique survival mechanisms have evolved to succeed against challenging and changing river specific circumstances, providing a possible solution to impending problems such as climate change.
  • The same applies to concerns over the loss of genetic integrity with respect to individual strains and different classes of fish. DIVIDED MIGRATION. JR Hutton's long term scale reading survey, based on over 50,000 salmon scale samples, shows the sophisticated way salmon have evolved to survive catastrophic events. Wye salmon will be returning in each of seven years after one spawning year, and that is repeated in each subsequent year. This ability to adapt and compensate would be lost in artificially reared fish.