The case of the radio-carrying salmon

Is the great experiment working, or is it not? That is the question fly-fishermen are asking on the River Beauly, north of Inverness - for this is the first spring in which it should be possible to gauge the results of the imaginative re-stocking programme which was launched four years ago.

For six centuries the river belonged to the Lovat family, but in May 1990 the fishing rights were bought by the newly-formed Beauly River Fishings Company, which began an ambitious programme of improvement. Part of this was the physical refurbishment of the waterway, and included the creation of new pools and the clearing of the burns in which salmon spawn.

This certainly seemed to help, for the annual catch leapt up from a 10- year average of 678 to more than double. Cynics may claim that part of the rise was due simply to more intensive fishing, but there is no question that the remedial measures have had a beneficial effect.

A more subtle challenge was to recreate the spring run for which the river used to be famous. Any number of salmon can be caught in June, July and August - but might it be possible to re-build April and May?

One fact of life on the Beauly, for good or ill, is the pair of hydro- electric dams built in the 1950s. Their good point, piscatorially speaking, is that they conserve vast quantities of water, some of which is constantly being let through, so that even in a drought the river has a good flow. The bad point is that they retard the passage of fish upstream, even though they are fitted with lifts which allow salmon to go through.

William Midwood, managing director of the new company, reasoned that the higher up the river a salmon is bred, the earlier it is likely to return from the sea, since it has farther to go to reach the breeding ground which instinct makes it seek out. In June 1992 he therefore arranged for over 100,000 fed fry (baby salmon) hatched from Beauly spawn to be planted in burns far up-river.

In due course these fry grew into parr, and then into smolts. Those which survived should have been washed downriver, over the falls and through the dams to the sea, during 1994. Now the first of them should be coming back as two-sea-winter salmon.

"Should be" is the operative phrase. As Mr. Midwood points out, "It's tremendously difficult to find out what's actually happening". Although not many fish have been caught yet this spring, everyone agrees that there are more salmon in the river than at this time last year. But whether this is due to the restocking policy, or to factors out at sea, nobody can say.

In an attempt to gain more knowledge, the company hopes to conduct a major radio-tracking experiment through the River Beauly District Fisheries' Board; but this would cost at least pounds 150,000, and a grant is being sought. Meanwhile, a small-scale radio project has yielded fascinating information about how fish approach the main hydro dam at Kilmorack.

Last summer 10 salmon were netted below the dam and fitted with radios. Three automatic listening stations monitored their movements: one as they approached from below, another as they entered the bottom chamber of the lift, and a third as they emerged from the top. Of the 10, only four went through, but the monitors revealed that the radio-salmon made more than 1,000 visits to the lower chamber.

Altogether, during the summer and autumn, some 10,000 salmon went through the dam. If this figure represents the same ratio as that of the radio- fish (40 per cent), it suggests that there must have been some 15,000 salmon in the river below. It further suggests that the catches now being made in the Beauly as a whole - 1,687 in 1994 and 1,395 last year - are at an easily sustainable level.

What fascinates me is the fact that, in spite of intensive study and the insatiable enthusiasm of experienced fishermen, so much about salmon remains mysterious. How, for instance, do they find their way back to their home river? Experts agree that taste guides them in the final stages, but before that they may rely on currents, changes in sea temperature and even a magnetic sense.

It is well established that when they enter the river, they cease to eat. Why, then, do they sometimes go for an artificial fly? Is it out of curiosity or irritation? Why, after several blank sessions, did Mr Midwood suddenly catch three in a hour one evening? And why, in particular, did no fish go for my fly in three whole days of casting? Failure cannot have been entirely due to my ham-fistedness.

Even if every salmon in the river carried a radio, I bet we still wouldn't know why it is that the fish will hardly ever bite.