In the shimmering rapids of the River Spey cutting through the Scottish Highlands, Ian Gordon casts his line with a lazy swing, waiting for a salmon to catch the fly.

In the early 1970’s when Gordon first fished the Spey as a ‘Wee Nipper’ it was never long before he had a bite. But things have changed.

“I would say it’s now at most 20 percent of what it was in the mid ’80s,” Gordon told AFP on a stretch of river near the town of Aberlour, where he runs a tourist fishing business.

Before numbers began to decline in the 1980s and 1990s, hundreds of thousands of young Atlantic salmon, or smolts, migrated from Scotland’s rivers to the sea.

A quarter would return to their natal rivers to spawn. Today, according to the Spey Fishery Board, only around four percent are coming back.

In Scotland, where anglers adhere to a ‘catch and release’ conservation code, the 2021 rod catch of 35,693 was the lowest number on record.

The Scottish Government said in a June report that the figures “are consistent with a general pattern of declines in the number of wild salmon returning to Scotland”.

Ecologists and fishermen say several factors are responsible for the decline, including overfishing of herring and the impact of the warming climate on the salmon life cycle.

“Herring used to be plentiful along the British coast,” says Gordon.

“It was a species that all species in the UK relied on. Since the herring were fished out, the salmon, which come into the sea as small things, become prey themselves.

“It is this cycle that is disrupted when a species is removed from the ecosystem.

“Of course, this is influenced by the climate, there is no doubt about that.”

Further north, outside the town of Bonar Bridge, Andrew Graham-Stewart stands on a bridge overlooking a creek.

“We have a real problem at sea,” says Graham-Stewart, who is director of the charity Wildfish Scotland and has been fishing in the local waters since he was a child.

“Climate change is obviously the main factor and there is very little we can do about it.

“But when fish go out to sea, they clearly aren’t finding all the food they need to find.”

One factor is the loss of trees on the headwaters of Scottish rivers.

Scotland has lost “probably about 95 per cent” of its tree population over the last few centuries due to agriculture, industry and wars, Graham-Stewart said.

Not only do trees provide shade for marine life, but they also slow the release of water from the hills, making for more consistent flows year-round.

“With tree cover and adequate currents, the water remains relatively cool and salmon need cooling to survive and thrive,” the charity director said.

Action has already been taken by some fisheries authorities, including on the River Dee, which flows alongside the Royal Family’s Balmoral estate, where Queen Elizabeth II died on September 8.

The Dee District Salmon Fishery Board and River Dee Trust have planted more than 200,000 native trees along river banks since 2013.

The goal is to plant one million trees by 2035 to restore water retention and protect salmon and other river species.

On the Carron River, in 2019, local groups removed a concrete weir built more than half a century ago to improve water flow and allow salmon a smooth journey.

For Graham-Stewart, salmon farming in the west Highlands and islands of Scotland has played a “massive” role in the decline in numbers by transferring sea lice to wild salmon.

Millions of fish in a concentrated area serve as a breeding ground for parasites, he says.

When the sea lice enter the farm, they multiply exponentially and are passed on to passing young wild salmon.

Once that happens, the salmon are eaten alive by the lice.

“The damage they (fish farms) are doing to wild fish and the environment in general is massive,” he said, calling for stricter regulations for salmon farms.

Fish farms firmly deny the allegations, saying protecting the environment and fish health is fundamental to their business.

At the Spey River, Gordon leaves the water without catching a fish.

He slips out of his waterproof waders and attaches his rod to the roof of his car.

Salmon, he believes, is a valuable indicator of human health as a species.

“It gives us an indication of whether the sea is in good condition or not,” he says.

“Right now they’re like, ‘Wait a minute guys — something’s wrong.’