For a period of five years WSRT ran a privately funded, lowland river salmon enhancement study. The project was established to research the problems and devise a defence against the possible extinction of a genetically pure stock of lowland salmon in the Hampshire Avon. It was never intended as a ranching scheme, the objective was to support the threatened stock of the Avon whilst enabling numbers of salmon to rebuild to a state of abundance within the river. The same is the objective on rivers such as the Tyne and the Wear in the NE of England, Whilst mitigation is the financial vehicle for the hatchery the habitat improvement, hatchery work and of course the NE nets buy-out have combined to turn around the fortunes of the rivers of the NE. We had originnally planned a ten year scheme to allow sufficient time to establish "Best Practice" and as the numbers we were restricted too by the EA were so small we anticipated a far longer period of assessment. Unfortunately the EA imposed further restrictions that made continued hatchery work on the Avon impossible.
Lowland Salmon Artificial Enhancement Rationale
Introduction
| Collecting broodstock from the net, from the left Founding member Mike Trowbridge, John Levell, netsmen Tim Edgell and Mike Paker |
Faced with a dramatic reduction in salmon population and MSW structure, fishery values and the very existance of rod and net salmon fisheries has reached a marginal position on the Hampshire Avon.
The EA policies on habitat improvement with special emphasis on gravel cleaning is a valid approach if somewhat simplified. Whilst EA budgets exist to direct toward this work, all is well. Should the cost fall back on riparian owners who through lack of fishery income can no longer afford to employ river-keepers, who traditionally did this work, the work grinds to a halt. This has been repeatedly illustrated over the past thirty or forty years on countless estates throughout the valley.
If what ails our salmon is of a more fundamental nature, average ambient water temperatures in the region of 10-12 degrees C during autumn and early winter. Enriched water through modern STW and fishfarm discharges, add agricultural leaching and perfect conditions exist for creating gravel clogging algal blooms. However clean the gravel to start, one hundred days exposed to a hostile environment is not helping recruitment.
In any marginal situation if one is unable to clearly identify the causes of decline one must take as many safeguards as are reasonably feasible to protect the fish stock. To direct all ones efforts into a single policy is flawed, particularly if that policy is incapable of being evaluated. A result of no evaluation is that we are also restricting the growth of our knowledge of the river. Lowland river artificial enhancement should be considered to compliment the work of habitat improvement.
In what form and to what extent? If one removes the obstacles placed in our way by the EA, broodstock procurement, broodstock numbers, confinement within catchment and insistance on complete tagging, the limiting factors are financial, labour costs and the physical procurement of broodstock. Sounds all to simple and with todays available expertise it is. What follows would be the ideal, it will attempt to illustrate where and why we are forced to deviate from the course of best practice.
Our start point must be to assess the present spawning escapement for the catchment. As no
accurate fish counting fascilities exist redd counts, rod and net exploitation combined with
the assesments of local keepers, anecdotal or not, must be used. Once we have arrived at a
figure, which by the nature of its compilation must have a wide margin of error, we must err
on the side of caution. As an example if we use the figure we arrived at for 1995 of
300 pairs +/- 50 our start point would be an escapement in the order of 500 fish.
If we are correct with this frighteningly low number the critical state of salmon stocks
on the Hampshire Avon is clearly evident.
We would wish to take upto10% of the run as broodstock to act as a safeguard for the species and allow for the expansion of our knowledge. The collection of information relating to the requirements of lowland salmon is a vital aspect of this policy, shallower gradients, higher fines, higher temperatures, greater human population demands, in river predation, all areas in need of research.
In order to minimise the effect on the wild population we would advocate that WSRT purchase all the fish from the Mudeford netsmen at no cost to the public purse. The purchased fish would continue to be floy tagged by the EA and released up river. Above the Great Weir to minimise low water entrapment and below Avon Causeway to allow non Avon fish easy return to the sea .Our subsequent collection of broodstock being based on a predetermined percentage of these fish allowing for rod exploitation and predation by pike etc. a figure agreed by negotiation.
These fish we would wish to take as near to spawning as possible, preferably within a fortnight - mid December. (with such low numbers spread throughout such a large catchment this would prove difficult if not impossible in high flow years. The final push to the redds, with the rains of autumn would be more realistic, allowing for trapping at weirs and hatches possibly proving easier but still not guaranteed.)
Logistically the exercise would require close co-operation of all the parties involved, EA, netsmen, riparian owners, WSRT and upstream fisheries. It does however offer a scheme capable of evaluation with a good scientifically based programme.
It would enable evaluation of the effectiveness of floy tagging and rod exploitation figures to be assessed more efficiently with a larger sample being released. This would also remove from the equation the genetic problem arising from the use of estuary netted fish, that of visiting fish from other catchments being incorporated into the scheme. It would provide fascilities to study the effectiveness of protected carrier release a valid approach proving successful for Atlantic Salmon in Canadian Federal Government hatcheries in New Brunswick. It is still the wish of the WRST to investigate in an effective programme the release of fry and parr into protected carriers. This was the original intention and we feel before the negative attitude toward artificial enhancement wins the day this is an important issue deserving of thorough evaluation.
Releasing hatchery reared parr with the television cameras in attendance.