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Something had to be done. The solution was devised by an Icelander called Orri Vigfusson, who is now a household name in salmon conservation. A partner in a herring fishing family that hit hard times when herring runs shifted, Vigfusson was familiar with the vagaries of fishing. Basically in sympathy with remote communities eking out precarious existences, Vigfusson saw that in order to endure the solution had to be fair. An international arm was needed to lend support and the quotas discussed at the negotiating table were assembled by the North Atlantic Salmon Conservation Organisation (NASCO), a multi-member body formed in 1984.
Encouraging alternative fisheries for the Greenlanders, and with striking success raising money all across salmon range, Vigfusson made his breakthrough leasing arrangement in 1993. The Greenlanders were not sold down the river – far from it. Their argument that the salmon fattened off their coast was accepted. The payment could be seen as a grazing fee. They were paid to abstain from their rightful fishery, beyond a small permitted tonnage for ‘subsistence’. No salmon could be exported.
The agreements have had to be regularly renewed and reassessed, a lack of finality seen by their critics as a weakness. There have been teething troubles. Greenlanders with limited opportunities for economic activity have exceeded quotas. Annual payments have been withdrawn, and then reinstated when malpractices have been straightened out. The way may have been tortuous, but it has succeeded.
A similar arrangement was reached with the Faroe Islanders, who had been shown how to catch salmon on baited long lines by Danish fishermen from the island of Bornholm who had perfected this art in the Baltic. By 1991 Vigfusson had clinched an agreement with the Faroese, made easier because the Icelandic government already had fisheries access arrangements to their seas with their closest neighbours. The Faroese were the only foreign fishermen allowed to catch Icelandic fish.
Vigfusson had shown how to raise money for salmon protection and how to broker international agreements on a new basis. Tirelessly he had circuited the salmon world, flying from one event to the next, rattling in buses round the bumpy roads on the Greenland coast, meeting one fishing community after another, making addresses and hosting fund-raisers, coming up with ideas for alternative employment, patiently arguing and negotiating. People had faith in his integrity and un-deflected purpose. He crossed national divides and came from a neutral country carrying no historical baggage. Salmon conservation using his model took a mighty stride.
Today there are still anecdotal tales, usually involving Spanish trawlers playing fast and loose with everyone and everything, but in the main salmon netting has being progressively removed as a major factor in European salmon decline.
Anglers knew they had to join the effort to restore the bountiful fish. Inducted in its virtues by an American salmon community almost completely stripped of their iconic east-coast visitor, and championed by the charismatic Alaskan-born angler and conservationist, Lee Wulff, who coined the memorable phrase ‘Gamefish are too valuable to be caught only once’, ‘catch and release’ was introduced to UK anglers around 2005. Since that time it has taken off. The fish is brought to the landing-net as fast as possible, revived by allowing the lungs to re-fill with oxygen, and let go when the body is properly horizontal in the water and the tail-movement quickens.
Talked of and practised by individual anglers for at least a century, especially when the salmon was late-season and coloured, catch and release took a formal position in salmon management relatively lately. Now it applies to fresh salmon in mint condition, not only coloured flabby ones.
Scotland’s Aberdeenshire Dee broke the mould and made catch and release compulsory all season in an unprecedented announcement that caused a mighty stir at the time. But it was done. Other rivers followed suit with milder variations on the theme. Some salmon were allowed to be killed ‘for the pot’ at times of year when runs were bountiful, and restrictions on numbers of fish allowed to be killed were applied to sensitive parts of the run, typically the early spring.
The result? Were there more shoals of salmon pushing the tide up the banks as they swarmed into those waiting river-mouths? Hell, there were! The decline persisted.
It was against this background of dwindling stocks that SALSEA girded its loins to find out what was happening in the part of the salmon zone that remained an almost total mystery – saltwater.
The background to this mystery was not only a fish that was doing a vanishing act, it was climate change. The north-eastern Atlantic, where many European salmon wintered, was warming. No thermometer was needed to discover this. Surf anglers on the north coast of Scotland’s desolate extremities threw their spinning lines baited for cod and hooked sea bass. Previously sea bass had not been caught further north than The Wash in south-eastern England. Exotic fish were dragged up in trawlers all the way to Iceland. Red mullet and sea bream edged up the latitude line. Coral reefs crumbled in unfamiliarly warm waters. Disc-shaped sunfish, previously only ever seen, and then rarely, off the south coast, were hauled onto boats far up the coast of Britain. From sardines to whales, fish moved northwards. Smolts were not immune; their pathways adapted too.
Oceanographers confirmed it: the North Atlantic was warming. For fisheries this presented challenges.
In 2011 there was a furious row in Europe’s fishing states when Iceland, not hitherto invited to the meetings which allocated quotas amongst traditional fishing nations, and not an EU member, discovered big shoals of mackerel swarming around its north coast, and started catching them. The Faroe Islands found and did the same. Tempers flared. The two small states became overnight pariahs. These fish ‘belonged’ to fishing nations further south. Iceland and the Faroe Islanders argued that the mackerel in their waters were in prime condition with top-notch fat content, perfect for market. For countries further south to limit their new bonanza was bizarre; the fish belonged to whoever had possession of them. The argument sputtered on. National politics had run up against fluctuating natural cycles, a test for diplomacy.
Fish follow temperature bands which are the conveyor belts for food. The mackerel do not care whether they swim off Iceland or off Ireland, they register the volume of shrimp and squid and other high-octane titbits that can be gorged upon, and follow them. Mackerel are not anadromous like salmon, with both a freshwater phase and a saltwater one, but their extreme mobility tested the capacity of nation states to live in a changing world. There were parallels with salmon politics.
The background to the search for smolts from European rivers was the same warming North Atlantic. There was a simple distance factor: the smolts from the southern extremity of salmon range in rivers in northern Spain had a longer journey to reach the winter food supply; further to swim, in hostile territory. All along the journey were the enhanced risks of predation and starvation. Conversely, as freshwater temperatures were also rising, smolts were growing faster in natal streams, and were bigger and often younger when they reached the salt. Ratcheting up the pressure, survival rates of fast-growing smolts are lower.
Celtic Voyager and two other research vessels embarked on their exploratory fishing trips in a world being re-drawn by dynamic flux.
Anxiety about the Atlantic salmon was sufficiently syncopated and international to produce the SALSEA programme. Although salmon smolts were the tools, the programme, lasting over three years from 2008, was designed to advance the understanding of ocean ecology and fish genetics. The authors even talk about hopes that they have provided invaluable data for ‘the future ecosystem-based management of the oceans’. Big aims.
To catch these very small fish in a large piece of sea they adapted a standard small trawl for smolt capture. A small-mesh net was pulled on two side ropes and kept on the surface by large floats on each side. At the ‘cod-end’, or last compartment in a narrowing cone-shaped net, was the fish ‘box’ accumulating smolts. The smolt trawl was towed in arcs at speeds of three to five knots, anything from 150 to 400 metres from the mother ship. It was 155 metres long with a mouth forty by ten metres. The main thing was – it worked.
Quantitative results varied by region. The report cites one case where 233 trawls netted 1,728 smolts and 53 adult salmon, at a rate of 3.4 fish per trawl. This trawl had hit a migration ‘pathway’.
The long-awaited paper, which included data collection from as far back as 1999, was published in January 2012. Authors Jens Christian Holst and Ken Whelan warn that owing to cost no such programme is likely to be done again. So we should heed what they discovered.
The location of smolts was closely linked to ocean currents. Differences in temperature and salt content change the density of seawater, which in turn drives global ocean circulation through the medium of currents. The young salmon use currents as escalators. They ride them for propulsion and add to this their swimming power. Recovered tagged fish showed that smolts’ swimming power was often equal to the speed of the ocean currents. They may be small but they are powerful.
Climate variability also affected where they went. Oceanic circulation round Scotland and the North Sea is anti-clockwise. It is also driven by winds, especially between March and May. As the climate alters, these winds have been strengthening and this affects marine growth and fish travelling in the upper layers, like smolts.
Smolts’ growth rate, as measured by SALSEA, is prodigious, fairly justifying the description ‘explosive’. Each day they might grow 0.6 per cent of their body length. At the southerly edge of Atlantic salmon range smolt survival is worst. Whether the young salmon were leaving the River Loire Allier in northern France and heading westwards round the Atlantic coast of Ireland to find feeding midway between Iceland and Norway in the Norwegian Sea, or leaving north-west Spain and negotiating the English Channel, southerly stocks struggled more. The impoverished Allier has only a bare-bones population of 500–1000 breeding salmon to start with, and the Spanish rivers are similar.
Norwegian and Russian young salmon, with less far to go, and feeding further north, do better.
When travelling off Norway Europe’s little silver fish meticulously follow the shelf-edge between the shallow coastal ledge and the deeps. The shelves form shallow-water skirts off the landmasses all round the North Atlantic where salmon winter. They differ from deep drop-offs, more characteristic of volcanic landmasses. The salmon’s landmasses have a glacial origin, shelving into the sea as glaciers turned to water. Why the smolts tracked the shelf-edge can be guessed at, how they followed an invisible fault-line underneath them is a mystery.
Richard Shelton was one of the scientists working on the early phases of research and he puzzled over this. How could the fish so accurately follow this shelf? Temperature, salinity and depth were tested for roles as routeing guides and none of them seemed to fit. In their lateral line, or the line running mid-body from end to end, salmon harbour the magnetic oxide of iron called magnetite. One possibility Shelton considered was that smolts were orienteering by the Earth’s magnetic field. This remains conjectural. But stick to the shelf-edge they did. This edge lies about halfway to Iceland. Knowing where they are is a first step to protecting them.
When they reached a projecting seabed north of Iceland called the Voering Plateau, our smolts ceased linear movement and dispersed in big gyres. In the Norwegian Sea and west and east of Greenland they feed and grow at what Shelton describes as, ‘rates rivalled by few other cold-blooded creatures’.
What was their pattern when moving? Trawling results suggested loose shoals of 100–700. There was no evidence of very large-scale shoaling behaviour, which was mildly surprising. So the canny scientists put closed-circuit cameras in the net-end at right angles to the direction of towing, to view better what was being caught.
The observers saw no huge fish agglomerations being gathered in the wings of the net, rather smolts ‘sneaking about’ as Shelton put it, in ones and twos. At night smolts were hard to find, and researchers reckoned that nocturnally they must dive deeper than the ten-metre-deep band they occupied by day. But why? Most fish rise in the so-called ‘water-column’ at night, as darkness affords safety from above. Behaving contrarily, diving smolts must do so for food. But what food? Or what improbable night-time threat are they escaping nearer the surface? Answers breed questions. The salmon’s mysterious behaviour has caused it to be dubbed ‘the oceanographer’s fish’.
The northwards drift of prey species sticking to their northwards-shifting temperature bands influences smolt locations. The team found that the smolts which reached western Greenland seas and settled north-west of Iceland, staying longer at sea and returning to the UK as hugely bigger multi-sea winter fish, were faring well.
The ability to track both regional and river-specific stocks of smolts at sea is new. Because the experiment’s focus was on fish from Europe’s main salmon rivers, the great majority of net captures were successfully ‘assigned’ to their river of origin. It is part of a wider knowledge-picture, where the factual fog is clearing over all migratory routes and behaviour. Microchip and tagging technology, along with a technique involving bouncing signals off satellites, have revolutionised knowledge about migrating creatures. The migratory wading bird, the woodcock, is the next in line for a tracking research programme. Across the natural world years of speculation are being replaced with firmer data.
The salmon fishing writer Richard Waddington devoted many pages of his 1947 book Salmon Fishing: A New Philosophy to a laboriously articulated theory that wintering salmon positioned themselves in the mid-Atlantic in order to intercept common eels migrating as elvers or ‘glass eels’ from the Sargasso Sea off eastern central America. Salmon swam with these easterly migrations of juvenile common eels, he surmised, being sustained and fattened by them all the way back to their growing zones in the freshwaters of UK and Europe. It was somehow a beguiling idea.
The author died long ago, but depending on circumstances in his afterlife he may now have the chance to reconsider and chide himself for those errant thought processes. Knowledge is a grand corrective.
Knowledge was meant to be a defining feature too of the revered Scottish ecology writer, the late Frank Fraser Darling. But when it came to salmon he stumbled. Fraser Darling wrote that the fish that ascend rivers early spawn at the bottom end, and the late-season runners go to the top. In fact it is the other way round, which is why today’s efforts to resuscitate the spring salmon, assuming that like breed like, take hatchery fish from the upper parts of rivers, not the bottom end. The top reaches are where the springers are.
He made another assumption which is fantasy: that east-coast salmon seldom come back from the sea more than once whereas west-coast salmon can breed four or five times. Scale-reading, which ages salmon, and should have put matters straight, had been around for over fifty years when he wrote this.
For some reason salmon seem to befuddle commentators. The director of Scotland’s Marine Laboratory, therefore the senior government person in fisheries, portentously declared in a book on salmon published in 2000 that it was now well established that ‘a large majority of the fish returning to spawn in a particular river originated from that river’. Wow, really? But that was what the Scottish Ecclesiastic Hector Boethius announced in the sixteenth century. SALSEA misroutes down this way too: ‘Reducing man’s impacts on our salmon stocks may be the key to ensuring their survival’. When can we move on, please? It may be a matter of debate whether the Atlantic salmon is the greatest of fish, but it is certainly the one that leads to most confusion.
Before SALSEA it was thought from examining pelagic trawls that smolts at sea ate blown insects to start with and moved deeper down the water column as they got bigger to find crustaceans and small fish. When the diet stepped up to embrace fish, growth accelerated. SALSEA saw that the diet of young salmon changes with ocean conditions. Researchers concluded that they ate almost anything. Capelin (found on the Canadian shelf and off west Greenland), young blue whiting, lanternfish, five-bearded rockling, sprats and sand eels all formed part of their sustenance. Smolts would consume eggs, larvae and young fish and zeroed in particularly onto a sort of bug-eyed shrimp called themisto.
Interestingly, the herring and mackerel which were moving in the same area, though themselves bigger, selected smaller food, mostly crustaceans called copepods. Smolts punch above their weight in the food chain.
Influences on salmon routeing included predator avoidance and their own growth. Uncircumscribed by physical limits, some young salmon migrate all the way not only to the Arctic ice-shelf, but under it. Presumably, beneath the ice-shelf at least one direction is guaranteed free from lethal attack, and there are no trawlers.
SALSEA leader, Norwegian scientist Jens Christian Holst, has written: ‘From the very first scent of salt these fish are continuously hunted by marine predators.’ They face different predator assemblages at different stages in their migration to the wintering grounds. Directly offshore, and whilst they are in the process of adapting their saltwater/freshwater balance for marine survival, sea trout, sea bass and cod feature. There are the salmon gourmands, seals. Further offshore those enemies are joined in the attack by saithe, pollack and more seals, and even rays and skates. North American Atlantic salmon face similar families of predators, but from local species.
Moving further out, coast-huggers like sea trout cease to be trouble. Diving seabirds such as gannets enter the fray. Minke whales and fin whales join the list of toothed adversaries. Even sharks, cephalopods (molluscs including cuttlefish) and tuna can eat smolts. Dr Holst says, ‘the list could be continued at length’! He adds that fast growth is an obvious survival aim for smolts trying to prolong their lives at sea. One sees why.
In eastern Canada a survival peculiarity has been noted linking smolts with spent kelts. In the straits of Ben Isle kelts gathered outside the rivers they had descended until the smolts joined them. Both young salmon and older ones then moved northwards in convoy to the feeding grounds. What is happening? Are smolts being taught their passage by their elders? Is there any protective function in the presence of the kelts mixed with the next generation? Another chapter in the mystery of salmon migration opens up.
SALSEA also recorded what effects human actions were having on smolt runs. Escaped smolts from freshwater rearing cages in lakes and lochs run as nurseries for the salmon farm industry, or young feral salmon, were identified by their genetic markers and found in numbers. Their groups were looser in formation than those of wild smolts. Just how many feral smolts were found is a matter tenderly circuited.
For it is a potent finding. Salmon farm escapement is a highly political and controversial matter and now science can tear back the veil on the resulting profile of ocean fish populations. The relevance for salmon survival of the presence of farm-origin fish competing with wild ones in the sea for the same food is a question which needs answering.
Scale-reading using digital technology was another tool in SALSEA’s knowledge review. Reading scales is nothing new and the Inspector of Fisheries in Scotland, Peter Malloch, based on the River Tay, developed basic scale-reading theories over a century ago. Wider spacing between rings told of richer feeding. From scales readers could say how well fish had fed and grown at sea, what smorgasbord of young fish, fish eggs and larvae had been eaten, prefaced by how these fish had fared in their freshwater phase.
Scales are like dentine in human teeth: they read like tree-rings and tell a story. The scales fall from our eyes: the biography of a fish is available in its scale history. In contrast to many fish population studies done for Europe’s Common Fisheries Policy using predictive modelling by computers to allocate catch quotas (an innately unsatisfactory methodology), scales reveal what conditions were recently like. They offer real-time information, not academic projections for the formulation of shaky assumptions.
Long-time series of salmon scale histories existed in several places. The Copenhagen-based International Council for the Exploration of the Sea (ICES) made available its archive of thousands of tagged and recaptured salmon details based on scale-reading. SALSEA took this forward. New developments in digital analysis have added to the knowledge bank to be gleaned from scale readings.
Scales read on adult salmon when they came back to rivers are correlated genetically to young smolts caught in the smolt trawls. Some of these scales had been taken from the adult fish long ago. So young North-Atlantic smolts were being traced by their scales to fairly distant ancestors. In total, 23,000 scales from seven rivers in six countries were studied. From this sample smolts were mostly two years old, some one and three years old, and a few four years old. The further north the river of origin the older the smolt age; southernmost smolts were growing faster in their home rivers and undertaking the marine migration earlier. As it happens, they were often dying earlier too.
The research revealed that smolts preferred temperature bands of 9–12°C and salinities over 35 per cent. They avoided the shelf directly off western Norway, possibly because salinity is low, and aimed for the deeper, more saline water further west on the shelf-edge. The colder the water the faster their growth rates. This is the opposite of growth and temperature effects in freshwater natal streams where colder water arrests growth.
One of the triggers for the whole SALSEA programme was the fear amongst salmon managers that certain pelagic fisheries in the salmon-wintering seas were sweeping up shoals of young smolts as a by-catch whilst fishing for other pelagic species. In particular there was concern that surface-trawling for mackerel and herring on the Norwegian Shelf was netting little smolts along with the rest and, in the worst scenario, inadvertently massacring entire populations from single river catchments. British fishery scientists had found Norwegian fishermen picking salmon smolts out of their pelagic nets and making special suppers from them. Russia has 40–50 trawlers working this sea far from anyone’s coast and therefore in international waters.
There is an internationally agreed fishery model run by the North East Atlantic Fisheries Commission, but it does not prohibit fishing on the surface. It has no smolt-protection aspect. This could be addressed. As Ken Whelan has said, the next phase is going to be political. Russia’s recent admission to the club of salmon fishing countries, where international rod angling is a serious financial sector, rejoicing in faithfully returning visitors willing to spend money in remote zones, may help this negotiation. Whoever thought that visiting the Kola Peninsular in the Russian Arctic would be a visitor destination of significance before the advent of salmon fishing? Now important Russians know the optimum meaning of a salmon, and the fish is becoming an icon there too.
Fishing states using these northern seas do conduct large-scale surveys of the ecosystem. Now that SALSEA has identified where the smolts are likely to be it becomes theoretically feasible to design pelagic or surface-trawling operations to minimise impacts on young salmon. Already in Norway’s wider fisheries regulations over too much of a particular by-catch triggers the closure of that sector until the unwanted non-target fish has moved on. The same might be possible in the herring fisheries of both Norway and Iceland to protect smolts there.
The other fisheries which may kill smolts are looking for blue whiting, capelin and horse-mackerel, termed ‘industrial’ fisheries because the lower-value fish are turned into fish-feed. It is a horrible irony that super-valuable young salmon are being enmeshed with large hauls of lower-grade fish used for conversion to fishmeal for aquaculture, quite possibly to end up in the stomachs of farmed Atlantic salmon. Valuable wild juveniles feed hordes of feedlot adults.
One improvement may be to alter the depth of pelagic fishing. If smolts occupy the surface of the sea down usually to six and at most ten metres in daylight, dropping lower at night, why not trawl lower still when the targets are herring and mackerel? When tried, this solution worked well. Whatever disciplines are adopted must produce an economic yield for the pelagic boats, and therein lies the challenge.
Ken Whelan is adamant that administrators in the EU fisheries division must be reminded that wise-use management of rare Atlantic salmon is now feasible. He talks of a future thinking in terms of protecting ‘corridors in the sea’ or ‘sections of the ocean’ for the smolt runs. Using known timings of smolt movement from the new migratory map it might be possible to abstain altogether from pelagic trawling where they are vulnerable and at the most sensitive periods. Such an aim sets the bar high.
Politics is never far from the marine resource scene. The impasse over the mackerel catch by Iceland and the Faroes, in an area not far away from the young salmon zone, is discouraging. Entering 2013 is the fourth year of the controversy and both the Icelandic and Faroese governments say they intend to continue harvesting their manna from heaven, though at lower levels. Iceland in 2012 was economically prostrate after a collapse of their banks; harvesting the valuable mackerel was an obvious recourse.
But time has shown that salmon protectionists are a powerful force too. SALSEA proves it, and it would be contrary to experience and history if the findings of this detailed study were simply to be buried and ignored. Iceland, for one, has a valuable sport fishery in salmon.
Development of the sport fishery has been transformational on Iceland’s western coast. Professionalised presentation of rod angling for migratory salmon as a lucrative tourist sector has been an economic triumph. Where not long ago visitors to Iceland rode ponies across the volcanic tundra, marvelling at the lunar bleakness and subsisting on a diet of puffins and mutton, now fishermen from all over the world tumble out of Reykjavik airport jabbering into their mobiles and pop-eyed with excitement at participating in one of the most charismatic salmon sport fisheries anywhere.
The water coursing over volcanic rock in treeless moonscapes is gin-clear, requiring peculiarly focused angler skills. There is no industrial pollution, people are rarer than puffins, the sea is a familiar element and provides the nation’s biggest income, and the newest landmass in Europe has an air of being truly virginal. Salmon-language is fully understood in this peculiar land of fumaroles and sulphur-belching hot springs. Agreements on salmon may form the basis for a new accord on other fish which colonise new territories, even mackerel.
Smolt stage is the black hole of salmon growth, and one reason why SALSEA ever happened. As fry and parr in rivers, the little salmon can be found and examined. Adult salmon are big enough to be tracked, at least some of the time. If they turn up on fishmonger’s slabs somewhere, people notice. Protection at that stage is a practical possibility. Smolts, in contrast, are needles in the haystack of the ocean.
SALSEA makes a stride in knowledge about salmon’s ocean phase. However, it did not satisfy all those awaiting its findings. Managers of salmon sport fisheries were looking for answers to their own pressing questions.
They complained that original promises on the development of the genetic map actually fell far short. Some tracking has limned in a few details, but the big picture remains largely unknown. They make the point that, interesting though genetics might be, the practical application of using the information on the average fishing river is limited. Say you discover there is a different genetic stock in one branch of the river – intriguing – but how can you manage the fishery, aside from keeping the tributaries in good health, to accommodate that information hidden in the DNA?
Most cogently, critics point to the report’s failure to nail salmon farming as the destroyer of wild fisheries through its lethal by-product of proliferating parasitic sea lice. The million-strong swarms of sea lice created by salmon-cage aquaculture adhere to smolts as they leave fresh water and kill them, thereby throttling wild salmon survival. They say the report’s equivocal and incomplete findings will leave politicians an escape route from firm and decisive action in favour of more time-consuming and inconclusive research, measures once sarcastically dubbed as designed, ‘to maintain the momentum of procrastination’.
They have a point. Some of the more arcane disputes about discrete genetic stocks in different branches of one river, and efforts to keep them pure, are undermined by the historical fact that river stocks have been intermixed long ago. All over Britain salmon have been moved from hatcheries and tipped into rivers wherever owners of fisheries wanted to beef up fish numbers, or revive them. It has been going on for over a century. It is the same in other salmon countries, too. Genetic purity is a myth, which is surprising given that genetic purity of stocks is the new mission for salmon theorists.
In Scotland re-stocking only with stocks from that river, and even from a specified part of the system, is now official ‘best practice’, to the frustration of many wizened fishery managers. The new knowledge about discrete strains is not being used in the most intelligent way.
It has always been hard for the genetics messiahs to deal with the fact that on the British west coast river where the Beatles originated, the Mersey, the water has been re-populated with salmon entirely by the vagaries of Nature, its own native stock having been wiped out. The Mersey now has Creole salmon of mixed origin coming from at least thirty different rivers. Who can object? ‘Nature hates a vacuum’ is true for salmon as for all else. Genetic straying has re-populated a major river.
The Thames is another melting-pot culture. Its tentative existence as a salmon river once again owes its brilliant success to stocks from many different places. Reflecting its diverse human mix London’s passing salmon population is polyglot too.
I saw a dramatic illustration of the basis for genetic straying whilst rafting in British Columbia late one summer. At day’s end our three rafts headed for a tributary with a nice shelving sand-bar to moor up on for the night. We crunched onto the beach and were stunned to find huge salmon lying dead on the water’s edge.
There was a biologist aboard. He looked closely at the fish and saw that their gills were clogged. They were king salmon, the big boys, and there were around forty of them stranded down the river-edge for a few hundred yards, all just above the tributary’s junction with the main river. The biologist said the fish were all within a day of spawning. So a valuable stock or ‘year-class’ of a rare and wondrous fish lay wasted about us never to breed, eradicated in the last moment of its evolutionary purpose. Why? The brown water was still silty from a landslide further upriver. A natural event had wiped out the big fish in this tributary for one breeding season.
What gave the event an added twist was the furious debate taking place in west Canada’s media that summer about threats to king salmon, their precarious status, and the need for firmer protection laws. Nature had thrown a joker onto the gaming table and we were staring at it.
But it was also where genetic straying and fish unfaithful to their natal imperative step in. Suppose, as we know is possible, that one pair of king salmon had gone up a tributary close by. They bred there. That strain of salmon thereby dodges fate and escapes elimination. In due course some of the progeny from that union relocate themselves as adults in breeding livery back in the original natal stream, and re-populate it.
Straying is Nature’s way of spreading risk. The same is true, surely, about the differing ages at which young salmon go to sea. If some ‘smoltify’ and migrate in their second spring, and some in their third, the risk of total elimination is spread. On big rivers in Scotland like the Tay, different grilse runs climb the system from early spring to the autumn. They are all fish which spent only one winter in the sea, the definition of grilse. Bookies call it hedging bets.
Peter Malloch might have had a lot to say on some of the purist preconceptions about river-stocking only with site-specific strains which have crept into modern management. It was Malloch who realised a century ago that salmon sometimes remained at sea a long time, and that not all fish were grilse as had been assumed before. He understood the salmon’s admirable diversity. The migratory fish turn homewards to reproduce, swimming south. It is presumed, but only so far tentatively claimed, that they follow the same passage, but going the opposite way, as that which they used as teenagers – another neat theoretical twist made available by modern science which this aristocrat of salmon analysis long ago would have appreciated.
Left behind in the marine larder are the others, the non-movers, growing and growing. Or not growing: some salmon a long time at sea are not especially big. Maybe they too are hedging their bets, passive actors in an evolutionary insurance policy.
A salmon’s eventual size is determined by its length; it can be fat or it can be thin, but without length it can never match the biggest. Girth is the feeding which beefs up the body length. Some of these wintering salmon spend two years in the vicinity of the Arctic, some three, some four, and some even prolong their Arctic sojourn to five years.
Turning southwards as the new year awakens, they ultimately acknowledge the ritual of reproduction, or so it is assumed. Scale-reading shows that after January sea-feeding picks up again following the short winter check. Thus, the fish achieve peak condition prior to the demanding migration south.
Today’s existence is tougher for salmon, for as the northern hemisphere has warmed, dragging the food supply northwards, the return journey south lengthens. Migrating salmon are starting further from home.
Krill may move, natal streams do not.
How long they take to swim home is unknown. Scale-reading differentiates between sea-time and freshwater-time, but we do not yet know in which sea, at what time. Could we? If scales were better able to track diet perhaps we could pin down more accurately how long the journeys take. Sand eels are on known sandbanks and capelin live in the north – the diet could position the predator.
However, there is another lateral-thinking way, a technique not yet fully developed for practical use. We need tags that could measure the angle of the sun at midday, then, as polarised sun filtered through the seawater, it would be possible to calculate latitude. Temperature and the intensity of the light are recordable now; the next step is a reader for polarised light. The tags used on smolts register temperature and depth, but so far they cannot measure the angle of the light. This tantalising technical advance may be not far off.
What is hard fact is that salmon are fast movers. When they do reach rivers they can travel incredible distances in a day’s journey, proven by the presence on them of sea lice. These are saltwater parasites which can only remain attached in freshwater for up to two days. Sea-liced salmon have been found thirty miles up rivers, and more. Fresh from the marine, Atlantic salmon are true Formula One fish, as some sparkling-eyed anglers have cause to know.
They do not, though, just arrive at the mouth of their natal river and motor into it. They savour the moment of transition, whilst making a vital physical adaptation to their water-balance mechanism. In the sea a salmon has to cope with water that is chemically stronger than its own body tissue, making it lose its body liquids. To compensate, a salmon at sea actually drinks seawater, which then passes through its stomach and intestine. Its kidneys expel small amounts of the salt in concentrated urine, conserving some of the swallowed water to make up for the liquid losses.
In his 2009 treasure-trove about the Atlantic salmon, To Sea and Back, Richard Shelton refers mischievously to the ‘uriniferous’ smell of farmed salmon: he has sound physiological reasons to do so! So many fish excreting powerful body wastes in a basin of seawater, only lightly refreshed by the average tides, might well produce some fairly rank odours and taint the aroma of the imprisoned inhabitants.
Entering the milder environment of freshwater a salmon finds its fluids more concentrated, not less, than those of its surroundings. It starts to absorb water through the permeable linings of its mouth and gills. The excess is filtered as dilute urine through the kidneys. So fresh and salt water are quite different environments. Salmon biology has the sophistication to occupy both.
Sometimes for weeks the fish pregnant with breeding preoccupations ride the tides near the river-mouth, tasting the fresh water debouching from the estuary, sampling it, experiencing the reawakening of chemical memories from long ago when they were fish only inches long. The expectant river-runners can be spied from the cliffs above estuary mouths drifting on the tide, maybe fleeing a hungry seal.
The year 2011 was dry for a while in midsummer in Scotland when I was sailing with the life-boat crew along the coast of east Sutherland. On a bright day in a calm sea we approached the River Helmsdale where the boat was to tie up. There, offshore, were leaping salmon, throwing themselves into the air. Those who see this often say they do it prior to entering the river, usually when a freshet of rain has gushed into the sea, bringing oxygen and water particles to their sensory receptors, stirring fusty recollections. Then, often waiting for the moon, they hitch a lift in like any surf-rider, selecting the highest tides.
Just as salmon unerringly follow the shelf-edge off Norway, so they unerringly seem to know what lies up rivers in the hinterland. If a river has lochs and lakes feeding it, salmon swim it earlier, for they can progress to a safe haven up ahead in the expanse of the loch. Scotland’s west coast has what are called ‘spate’ rivers, because they are shorter than eastern rivers, and salmon generally run into them during or after rain when water levels are higher. These fish know there is often no sanctuary or a loch; their only refuge is a deep pool, and it might already contain other occupants. On the River Helmsdale we know from the presence of sea lice on fish caught by anglers that many salmon run straight through the 24-mile system and forge on through the fish-pass into the chain of lochs at the top where they can safely bide their time until autumn spawning.
The river system made in heaven is perhaps the one with big headwater lochs providing a sanctuary for the salmon and an inducement to run the river to get to it, thereby presenting anglers with chances of an encounter. Even better, possibly, would be the system with a big loch in the middle, with salmon filtering into it from below and out of it from above, the loch also acting as a natural regulator of water levels.
Sometimes forgotten are landlocked salmon. They lack the mystique of the ocean rover, and they do not leap waterfalls to remind us of their grace and power. More importantly they do not have to worry about smolt losses to cetaceans, Russian trawlermen or any other conventional threat. Pike with backwards-curving teeth might be their toughest adversary. In addition they need none of the adaptive mutations for moving between saltwater and fresh.
The lines are not hard and fast. In anadromous salmon populations some parr never leave their rivers and behave as landlocked salmon, awaiting the return of gravid hen salmon for their sneaky off-chance at fertilising the next generation.
Perhaps it should not be surprising that populations of landlocked salmon comfortably survive today. In Norwegian, Swedish and Russian lakes there are landlocked salmon as well as in North American ones. These northerly receptacles of cold water never heat up too much for salmon’s tolerance. Landlocked salmon could be compared to brown trout, happy not to migrate whilst some of their siblings run the gamut of the wilds to become sea trout.
Norway’s huge Namsen River has a majestic and impassable waterfall. Whilst I was watching its awesome power and letting the physical reality of the cascading torrent sink in, the droll ghillie told me that only the week before a visitor angler playing a feisty salmon from a downstream-drifting boat above the fall had failed in his battle-concentration to notice the advancing roar of the crashing water. He went backwards over the top, attached with his fishing line to the fish of a lifetime, and was never seen again. The story was relayed with barely suppressed ghoulish relish. Did he get his kicks telling that story every week? At any rate, above the Aunfoss waterfall subsist the resident salmon which never migrate, cut off by a giant curtain of cascading water.
Landlocked salmon are not uncommon in North America. In Idaho I have seen the scarlet kokanee, which are Pacific-origin coho salmon, and I found the sight somehow disturbing. Here are these small shoals of highly coloured fish in the translucent shallow waters of rivers and lakes, looking nervous and wary. You sense they are trapped, freakish prisoners, despite their presence having been determined by ancient geology. Really, they are true and admirable survivors, but it does not feel like that. And their chromatic violence in the drab landscape adds to a sense of displacement.
In Lake Ontario the early settlers found landlocked salmon weighing up to forty pounds. So much for the sea only being able to build up weight; pike disprove that and the lake salmon underlined it. These monsters, however, are now gone. In Maine the landlubbers are called ‘sebago’, being the name of lake in which they were first identified, and in other Maine lakes there are different varieties of salmon non-migrants.
To an angler a salmon is in its natural place in a river. That is where an encounter can occur. A river is the proper mis-en-scene for connection with the fish by a wispy length of nylon on a bendy stick, and a hook maybe no bigger than a gnat. What salmon do in rivers is a subject upon which fishermen have ventured opinion in a veritable lexicon of viewpoints. Seldom has so much speculation been focused on one inhabitant of our environment. How many shelves could you fill with the books which have celebrated the mysteries and majesties of moles, rabbits or hedgehogs?
Long ago debate centred on whether salmon eat in rivers. It seemed impossible that a large creature could enter a river a year before undertaking the rigours of spawning and live off its reserves. Anyway, why did they take fishing flies if they were not eating?
Peter Malloch, as Scotland’s Inspector of Fisheries, seemed to have nailed the matter way back. He and his team eviscerated thousands of salmon. They never found anything in the stomachs, no matter how long the fish had been in the river. Even if, as happens in a few places, salmon over-winter in a river and do not spawn till late the following year, they still do not feed. It is a stupendous fast. However, it failed to stop many subsequent armchair theorists raising spectres and postulating that salmon must eat, that sundry reasons existed for their stomachs being empty, that what was evident knowledge was as full of holes as a colander. The fact, amazing as it is, remains: salmon cease feeding in freshwater. Like snakes, which can live for months, even years, without eating, salmon subsist on their stored marine reserves. If they open their mouths to seize fishing flies in rivers, fishermen may claim they have been artful enough to override behavioural rules; angler achievement is all the greater. Not quite as great, though, as the biology of their quarry.
An area for debate between anglers and salmon professionals is whether the leaping salmon is moving upriver or not. So many times ghillies and anglers talk of ‘fish running’, meaning they are ascending the ladder of the river-system. But if you watch salmon from under a river at their level, as is possible in the riverbed salmon museum on Sweden’s River Mörrum, you see that jumping salmon may move slightly forwards from where they took off but they drift downwards as they descend in the water-column, landing back on the launch pad. Salmon maintain their station more than some of their aerial antics would suggest.
Whereas anglers believe that salmon are running past them, and sometimes try to hasten upriver and get ahead of them, river counters using electronic beams show that salmon ‘run’ mostly at night. Summertime salmon almost invariably use the cloak of darkness to hide their journey. Some counters work with parallel sets of beams, interrupted beams signifying a fish swimming upriver. Counters can be calibrated so that only fish of a certain size register, excluding smaller ones and trout.
