Anglers get that shrinking feeling as Scots salmon fail to measure up

Published on Sunday 12 June 2011 16:12

SCOTLAND'S wild salmon are shrinking dramatically in size, experts have said.

Last year, a record 100,000 wild salmon were landed by anglers. The haul - the best since records began in 1952 - was lauded as a justification for strict conservation measures which have cost millions.

But it now appears there is a catch - and not the one anglers want to hear. Far from being more fish in the sea, there are actually many less and they are lighter and shorter. Once famed for its long, plump and pink flesh, the king of fish is shrinking.

A major study of the species in Scotland has revealed the average grilse - young salmon which have been at sea for just one year before swimming back to their home rivers to spawn - are a third less heavy and have shrunk by nearly a tenth.

Scientists also claim that there are a third fewer salmon in the Atlantic than 40 years ago, with twice as many as previously dying at sea before reaching their rivers.

Despite stopping big commercial fisheries in the salmon's feeding grounds off West Greenland and the Faroes, and anglers voluntarily returning tens of thousands of fish, there are simply fewer salmon in the sea.

The research has formed part of the most comprehensive international study of Atlantic salmon ever undertaken. Costing 5.5 million and lasting seven years the results of the SALSEA project will be delivered to a symposium in September at La Rochelle, France.

But one of the salmon experts, Professor Chris Todd, professor of marine ecology at St Andrews University, said it was not just the number of salmon that was a concern but their quality.

He said that by monitoring an un-named major Scottish river for the past 17 years, he had found that the weight of the average grilse had fallen from 2.4kg to 1.7kg, and that its length had shortened from 59 to 54 cm.

"It is pretty dramatic and very worrying," he said. "The fat content in the fish has also declined by about 80 per cent.

"People may be catching lots of fish but the quality is poor compared to the historical record. Also larger fish tend to produce more eggs. We don't yet know about the effect on egg quality - skinny fish may produce poor quality fish. It could be a vicious circle with big impacts for the future of the species."

Prof Todd said he suspected that climate change was the cause of the shrinking salmon.

The water temperature in the feeding grounds had increased by as much as 2 degrees C - which from a base of 8 degrees C was dramatic. This has the effect of pushing the plankton that the young salmon feed upon further north.

"To find salmon that have now spent three, four and five winters at sea - the very big fish - is rare. Despite the closure of fisheries and coastal netting, and the effects of catch and release by anglers, the number of fish coming back to their rivers has been going steadily down, as has the quality. Something quite unusual is happening and all the problems point to this happening at sea."

The life-cycle of the Atlantic salmon involves migration to the sea, where growth is rapid. In Scottish rivers, most salmon migrate after two to three years. The oceanic phase can last from one to four years before the salmon return to the rivers of their birth to spawn and complete the cycle.

Sir Peter Hutchinson, assistant secretary of the North Atlantic Salmon Conservation Organisation - which is running the SALSEA project - said the research had managed to even genetically sample salmon on their 2,000 mile migration.

This meant that it was possible to tell which river or region smolts had come from.