Habitat improvement ... why it works for us

You will have gathered that the thrust of our work has been to get fish back to the areas in which they used to spawn. Very often, we are asked about the benefits of such work and it is important to try and explain why we feel it is so essential. We are also asked whether it might be better just to stock the headwaters.

The issue raised by these questions is fundamental to the whole way in which we run our revival programme. First, we need to understand just what exactly are the problems with the headwaters. There are essentially three main difficulties.

1. Fish have been denied access to a large area of their natural spawning grounds.

2. Insufficient numbers of fish are allowed to escape to spawn.

3. Habitat degradation of the nursery streams has reduced productivity.

We believe it will be necessary to correct all these problems to restore the river to its former status as a major salmon and trout fishery.OPENING UPBy opening up areas that, for whatever reason, are unavailable for young fish production, we will not only increase our population of fish but it also happens to be the cheapest way of bringing about any improvement. Provided the streams are kept open either by fish passes or a maintenance programme, the improvement is, to all intents and purposes, permanent. Once the whole river system is as fully open as practical, further sustainable improvements can be made by improving the "Habitat".

HABITAT IMPROVEMENT

The idea is to restore the condition of the stream such that quality and quantity of food supply, shelter, sanctuary and the like approach their former state. A productive stream with abundant "territories" will minimise the huge losses between fry and parr stages. It is possible to quantify the productivity by reviewing density of parr recorded in the EA electro fishing reports. Figures in excess of 15 salmon parr per 100 square metres are ideal. The average for the Wye is nearer four. In practical terms, this means reducing erosion and siltation by fencing off the smaller nursery streams and letting in more light where tree cover is excessive. Creating bankside buffer zones and even planting trees where appropriate. Pollutions need rectifying and abstractions checked. A DEGREE OF IMPROVEMENTS TO FISH DENSITIES CAN BE MADE EVEN WITH EXISTING NUMBERS OF ADULTS. The benefit is likely to be greater for trout.

INCREASED ESCAPEMENT LETTING THEM GO

With spawning targets as low as 45% at the moment, the benefit of leaving more fish to spawn is another obvious way of improving our fish stocks. Reaching that target would effectively double fish production but, most importantly, this would compound on the benefits of access and habitat improvement.

Access work, when complete, would double the output of the smaller tributaries (this would be a total increase of 1.3 on the entire system when you include the main stems) but amounts to a factorial increase of 2.6 when sufficient fish are spared. If the habitat of all these little streams is restored, then a further increment of x3 is possible to the tributaries contribution to fish production. In all a possibility of over a five-fold increase, if we ever complete the work as planned!!

This complex subject will undoubtedly need further elaboration and so in the next issue, we will ask Dr David Summers to explain in more detail.

HATCHERY SCHEME

There is a hatchery scheme on the Wye run by the Wye Salmon Fishery Owners Association (WSFOA). Hatchery work has often attracted controversy and has always needed heavy funding. As a responsible fisheries trust, the Foundation's view of this work will always be guided by expert scientific opinion and we are in full agreement with the various professional advisors of the WSFOA. We hope to have their views in the next issue as well.

GARTH DULAS WILL THE FISH PASS?

Some months ago the Environment Agency finally promised to build a fish pass around the weir on the Garth Dulas (Irfon tributary). This weir was totally rebuilt 10 years ago without a fish pass, with the knowledge of the Authority, thereby blocking the access of spawning salmon to what had been one of the Wye's most productive spawning and nursery streams.

The Environment Agency calculated that once installed, the fish pass will result in the production of at least 2000 extra smolts per year from the Garth Dulas.

Sadly the Environment Agency didn't build the pass in time for the 1996 spawning run and on several occasions our Habitat Manager, Richard White, saw considerable numbers of salmon stuck below the weir trying, without success, to ascend.

It is with great relief that we can report that the project is nearly complete and in the next issue we hope Bill Purvis of E.A. will be able to explain in detail the benefit of this major scheme.