ANOTHER LIFE:THE VALLEY BEYOND the mountain is gloomily magnificent and also often very wet, as the rocky pate of Mweelrea scrapes the rain clouds sailing in from the Atlantic. The tail-end of Hurricane Hanna merely topped up the waterfalls above the valley's two dark lakes, Doolough and Finlough, in a summer that delivered 390.8mm of rain in August alone - getting on for twice the 20-year average. But the Delphi salmon anglers flailed doggedly on, even as their country-house refuge was cut off by floods and little landslides skidded down the mountain slopes above, writes Michael Viney
The August bag of 135 salmon set a record, and a fish of 15lb 5oz was the biggest in some years. Only a small number were wild fish, each returned to the water at once unless it was an angler's "first"; the rest had been born in Delphi's own hatchery and thus could be kept. But the season's tally was still way below what was hoped for. Despite the ban on drift-net fishing, the overall mortality of wild salmon at sea remains frustratingly mysterious.
The Marine Institute station on the Burrishoole River at the head of Clew Bay has been monitoring the fate of wild and hatchery salmon since the 1970s, only too aware that coastal nets were intercepting most of the fish returning to spawn. Now, after years of tagging programmes and genetic study, its researchers are among those following juvenile salmon, less than 30cm long, from the rivers of Europe to their feeding grounds off east Greenland and the Faroes, and in the Barents Sea.
The head of Ireland's salmon research, Dr Ken Whelan, is president of the North Atlantic Salmon Conservation Organisation, one of the consortium of 20 organisations backing the EU-funded SALSEA-Merge project, a rare partnership of geneticists, oceanographers and ocean modellers. The Marine Insitute's research vessel, RV Celtic Explorer, sailed from Donegal in May on the first of three survey voyages, and a parallel programme for the northwest Atlantic took place in August, with Canadian and US involvement.
The researchers are using genetic "fingerprinting", which has already helped to map all the major salmon stocks in Europe, to match the young fish caught in their first year at sea (post-smolts) to their home rivers. They are caught in trawls designed to fish at the surface of the ocean. Even with nets 10m deep and 60m wide, the chance of catching any may seem impossibly random. But their northward migration to feeding grounds in the Norwegian Sea and around the Faroe Islands is guided by swift currents sensed most strongly at the edge of the continental shelf.
On the first Celtic Explorer voyage, more than 250 fish were caught above steep shelf slopes northwest of the Scottish Hebrides.
This included one haul of 140 - a striking confirmation of their migration route. A further cruise by a Norwegian research vessel searched for young salmon at the northernmost range of their summer feeding in the seas off southeast Greenland and northeast Norway. Here the catch was far leaner, but 31 trawls yielded some 80 young fish, a few in almost every haul, along with other species. None of these salmon had been tagged by anyone.
There will be more voyages next year, and genetic analysis will match them to rivers as far south as France and Spain, where salmon are now critically endangered. At the time they are caught, the sea is sampled for temperature, salinity and available zooplankton food. The fish themselves are individually photographed, measured, sexed and weighed, their tissue sampled, their sea lice counted and stored for identification.
There is no shortage of theories for the salmon's decline - climate change and its impact on ocean currents and zooplankton are major concerns underlying the new research. The erratic return of salmon to Delphi at "absurdly small" sizes after two winters at sea has certainly suggested feeding problems in the ocean. And the impact of sea lice from salmon farms (this despite chemical control and close monitoring by the Marine Institute) remains a stormy issue.
The destruction of west-coast sea trout (which migrate to and from the sea at the same rivers as salmon) has long been attributed to lice multiplying at the farms. Now, their possible toll on migrating wild salmon smolts arises from experiments with thousands of tagged hatchery fish released from the Delphi and Erriff rivers, some treated with an anti-lice chemical administered in their food and some not. Recoveries of the fish as adults have so far shown a wide-ranging difference in survival rates, with most recaptures among the treated fish. The smolts of wild salmon leave the rivers without such protective doses.
EYE ON NATURE
During a rare interval in our incessant downpours recently, a lovely red-bodied damselfly, Pyrrhosoma nymphula, rested on my garden wall. A rare treat in this part of Dublin.
Rodney Devitt, Sandymount, Dublin 4
A lone raven has taken up residence around Redford Park for the past six months. It perches on trees, rooftops, street lights and, recently, on the crucifix in Redford Cemetery. It spends time giving out to the world and perfecting its mimicry of other crows. Any other solitary ravens inhabiting suburbia?
Kieran Fitzpatrick, Greystones,
Co Wicklow
While crossing a field adjacent to Citywest Hotel, Dublin, I had a raptor experience. I saw five buzzards ascending from a copse of ash trees, then a female sparrowhawk pounced on a wood pigeon in the field, and overhead a pair of kestrels put on an aerial display.
Mark Glynn, Maynooth, Co Kildare
I found a massive moth sheltering from the rain. It had a wing length of 65mm, grey wings, black, pink and white stripes radiating from a line of grey fur down its back.
Paul Cousins, Wexford
It was a convolvulus hawk moth, which is a summer visitor from Africa in the southeast.
Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo; e-mail: viney@anu.ie. Include a postal address.