Restoring the Vosso

What must be the most intensive and comprehensive salmon recovery programme on any river is to be launched on Norway's River Vosso.

The Norwegian Directorate of Nature Management has drawn up the rescue plan after a long-running study blamed the sustained failure of the river stock largely on salmon farming in fjords.

Stocks collapsed in 1988 and have not recovered although salmon are still present in the river due to escapes from farm pens and hatchery programmes. Vosso salmon genes are preserved in a live gene bank and the directorate plans to use its gene bank reserves, that can not be preserved indefinitely, to re-establish the pure Vosso strain.

The research looked at a series of possible contributory factors to the Vosso salmon's decline, including:

* Lowering of the Vosso lake (1989-1991).
* Road-building close to the river in the late 1980s.
* Acidification of water.
* Escaped farmed-fish spawning in the river (60 to 70 per cent of the catch in recent years has been escaped farm-fish).
* Sea-lice from fish-farms killing outward migrating smolt.
* The Evanger hydro-power station creating lower summer river temperatures and more acid water.

Of all these possible contributors, the report concluded that the most persistent overwhelming damage to stocks was caused by sea lice killing returning smolt and the escape of farmed salmon diluting what remained of the gene pool.

Earlier problems, such has acidity, have been resolved through better water quality. Fry survival from hatcheries in the upper river has been encouraging. But smolt still struggle to run the gauntlet of the salmon farms.

More recently conservationists have begun towing batches of smolt in special cages through the fjords, giving salmon farms a wide berth. Smolts are also being vaccinated against sea-lice attacks which research has shown is another significant aid to survival. Return rates have improved as a result.

Now the directorate is to consolidate the most successful initiatives in a programme that will re-introduced the Vosso gene. The programme has a two-pronged strategy aimed at both improving the quality and survival rates of Vosso salmon smolts and at lessening the damage caused by salmon farming.

Specifically the programme intends to:

* Establish production of 1.5 to 2m eggs a year in the gene-bank through increased breeding stock.
* Increase the capacity in the Vosso hatchery.
* Implant 1 to 2m "eyed ova" during wintertime.
* Release 200,000 to 400,000 one-summer fry.
* Establish a part of the upper river that has no natural run as a "living gene-bank".
* Release 100,000 to 200,000 smolt at different parts of the migration route, and with different treatment regimes against sea lice attacks.
* Establish a regime for marking all genetic material.

To limit sea lice attacks on smolt it intends to:

* Coordinate anti-sea lice treatments among all fish farmers.
* Control sea lice levels.
* Move some fish farms.
* Catch some of the smolt in river, and tow them out to sea (tests have shown this methods produces much higher return rates).

To limit escapes from fish farms it will pursue the following initiatives:

* Instigate better escape-prevention.
* Limit net fishing in fjords.
* Insist on the release of all wild fish (marked) and the culling of escaped fish.

It's good to see such a co-ordinated response. To succeed it will need the co-operation of powerful salmon farming interests with a view, perhaps, to a shrinkage or radical repositioning of salmon-farming in future. That commitment does not exist at present but if this initiative fails it could be the only answer. If the plan succeeds we may yet get the opportunity to fish for those magnificent Vosso salmon once more.

Material for this report was supplied to me by Riise Bjørn of Klæbu Sparebank in Norway who has been monitoring the Vosso programme for some time. He describes the Vosso as "a unique biological resource." I would second that.

What ever happened to the Vosso?

For some time now I have been curious to know what happened to the salmon runs on Norway's Vosso River that I read so much about in Arthur Oglesby's book, Salmon.

I started a discussion about it here in this fly fishing forums thread. After carrying out some recent work looking at the salmon farming industry I am now convinced that salmon farming was largely to blame.

There is an excellent feature about the river in the Winter 2007 journal of the Flyfishers' Club. The feature, written by Morten Harangen, mentions a recent fishing trip to the river when he failed to catch anything.

He says the record book for 2005 mentions "seven or eight" salmon caught on the river. But were these genetic Vosso salmon? Or were they escaped farm salmon? It does not say.

The catch is pitifully small, even if, as Harangen asserts, "there is no doubt there are still a few forty to fifty pounders out there."

I hope he is right. What will be difficult to discern is their genetic purity. On the other hand there is every reason to believe that something, if not entirely genetically pure, then very close to the original strain, could be restored even if it hails from a salmon farm cage. This is because a significant constituent of the Mowi strain, the first salmon farm fish to emerge in Norway, were salmon taken from a Vosso tributary, the Bolstad.

These large-growing fish are typically four or five sea-winter fish. The more winters that salmon spend at sea, the bigger they get, hence some excitement in the May Tay Salmon news bulletin from the Tay Salmon Fisheries Board, that a good proportion of the Tay's spring fish this year appear to have been bigger three-winter salmon.

All well and good - I'm as delighted as anyone to see evidence of big spring salmon back in the Tay - but the run is still relatively small compared with the 1970s. A few big salmon does not a spring run make.

As for the Vosso, it was closed in 1992 and re-opened in 1998 without any signs of improvement.

So why did the river collapse? Karl Magne Bolstad whose Berga farm overlooks the Bolstad pool, and which has some of the most famous beats on the river, has no doubt that many smolts were killed by sea lice that accumulate in large numbers around salmon farm cages. But there was also a lot of dumping in the river when a road was built. That killed a lot of fish, he says. Moreover a power plant constructed on the river led to significant changes in water temperature, another possible contributory factor.

It's astonishing how human activity in different areas has collectively destroyed one of the world's most precious wild salmon rivers with barely a whimper of protest. Today, hatchery-reared smolts are being transported past the salmon cages but will that work as a conservation effort?

Bolstad does not sound too optimistic of restoring the strain. A once mighty salmon river, its fish the stuff of legends, has been lost to angling and may never return. That's a crying shame.