The Salmon: The Extraordinary Story of the King of Fish. Michael Wigan

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СКАЧАТЬ 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 СКАЧАТЬ