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