UNDER ATTACK

The protection of young salmon is key according to Michael Wigan

The spring salmon season is haltingly underway. On the big rivers the picture generally has been quiet. Hotspots, as ever, exist – on the Kyle of Sutherland’s Carron tidal water one local angler had caught 20 by mid-April. But most attention has focussed on the salmon farming inquiry, and the fanfare launch of the Atlantic Salmon Trust’s ‘Missing Salmon Project’. It aims to raise £1 million for research starting in 2019.

Its focus is smolt survival, which is obviously paramount. What comes back must have gone out. But there is a red alert about in-river life chances of smolts. The figures are revelatory. By tagging smolts higher in rivers and recording how many reach river mouths using smolt traps, it has been shown that on the rivers Conon and Dee mortality of smolts reached 70%. On the Deveron it was 60%.

For the first two to three years of a salmon’s life survival is relatively assured. Electro-fishing results measure and record fry, parr, and smolts. On many Scottish rivers edgy young salmon lurk behind boulders, hide under banks, and hone good survival instincts. Their enemies are herons and creatures that prise them out of the comfortable corners, like fellow resident brown trout.

As they get bigger and turn silver, the trouble starts. Smolts migrate around May. All anglers have seen this: the flipping and splashing of shoals moving down-river to reach saltwater, dressed in new saltwater camouflage.

Away from their familiar residences these oily titbits are easy pickings. Cormorants, mergansers and goosanders face upstream and position themselves for smolts to swim down their throats. At river mouths the bigger maws of seals hunt more.

Salmon survival may be toughest at this critical stage, the same stage incidentally as that during which the chemical signature of individual rivers is printed on salmon memories, directing them to return to natal rivers rather than alien ones.

The Missing Salmon Project intends to track smolts in the Moray Firth, which hosts 35% of Scotland’s salmon migration. Electronic receivers will stretch to the corners of the firth at its wider point, between Aberdeenshire and Caithness. The target is to follow 1,000 smolts from five major rivers up to 56 miles out to sea, identify the main leakage points, and then develop solutions to help survival.

The angling world has produced an interesting array of opinions. Some say tracking to 56 miles is not far enough for useful results. Previous smolt tracking by the SALSEA research team in 2008, was funded to £5.5 million and the effort was international. SALSEA scientists netted smolts 100 miles off the Norwegian shelf.

The sudden and unexpected 2018 surge in Scottish populations of mackerel and herring, both subject to tight catch quotas since their collapse in the early 1980s, is relevant. In July and August their diets overlap with that of smolts. As smaller competitors, smolts could be overwhelmed.

Do the billions of sea lice produced by ever-bigger salmon farms latch onto smolts passing north, as they must, through the Minch and off the northern isles? That thousand-dollar question could be dynamite for the government’s darling industry.

In truth, the whole salmon migration at sea needs tracking. The Atlantic Salmon Foundation in America is working on placing receivers on the ocean floor and pinging tags in passing salmonids, marking a major advance.

A more immediate focus does exist. Smolts could most easily be protected during their freshwater passage to sea in May. At the stroke of a pen, licenses issued to control predation by sawbills and cormorants could ratchet predation right down.

However, it is a tricky world. The SNH chief who issued licenses to control 60 lamb-eating ravens in Perthshire attracted death threats from internet trolls. To some of today’s re-wilding groupies, restricting any natural predation – whatever the justification – represents surrender to sectoral interests.

AST’s challenge is making sure their £1 million, if raised, follows its science with practical recommendations.

In truth, the whole salmon migration at sea needs tracking