A BRIEF OUTLINE FOR OBSERVERS
Nick Tregenza untangles the bewildering variety of fishing gear, which continues to evolve and which is often confused in news reports. As Nick explains, the different fishing methods also vary greatly in the ecological problems they cause.
Netting (used by "netters") nowadays refers to gill nets made of nylon, either monofilament - like some anglers' fishing line - or multifilament. Gill nets mostly trap fish as they try to swim through a hole that is not big enough but "trammel" nets have a slack small-mesh net sandwiched between very large mesh nets, so that a fish or crab can push a pocket of the centre net through a hole in the outer net and get caught in it. Most nets are "set nets" - set on the bottom, and attached to a heavy foot rope and headline floats so that they stand up like a wall. Hake nets have two foot ropes with "legs" between so that crabs can walk under them, while tangle nets are rigged with a lot of slack along their length and are large mesh. With very little buoyancy in the head rope, these nets lie close to the bottom and trap bottom-living fish. Many of these fish are used to sitting still and will remain alive in the net for several days, in contrast to hake and cod which die quickly in nets.
Tangle-net fishing seems to be growing and is used by many inshore part-time or amateur fishermen who rely on the ability of the catch to stay alive to allow them to visit their nets infrequently when weather permits. This easily runs into neglect and nets can be seen around the coast heavy with weed and still catching fish that are rarely retrieved.
Wreck nets are simply ground nets set over wrecks, where the damage they suffer from snags is offset by the value of the catch.
An offshore netter 15 metres long will carry a crew of five men and stay at sea for a week or so at distances from home of up to 400 miles. Each day they will set and haul about 12 miles of net. The UK now has 40 or more freezer-netters that stay at sea for weeks and set 100 to
300 miles of tangle net, mainly along the edge of the continental shelf, for monkfish. The catch and the "by-catch" or unwanted catch in these nets has never been studied by independent observers but they are the fastest growing sector of netting in the UK.
Set netting has real ecological strengths - it catches fewer undersized fish than trawling and is a relatively low-energy method. Its main ecological problem is its by-catch of crustaceans and cetaceans, especially the porpoise. The catch of members of the shark family, the elasmobranchs, also causes concern as these fish reproduce much more slowly than bony fishes, and several species are in critical declines under all forms of fishing pressure that are known.
Drift nets are like set nets but the floats are bigger and the leadline lighter, so the net hangs like a curtain from the sea surface. They were once a major method for catching mackerel and pilchard, and more recently tuna. The tuna fishery in Biscay caught about 2,000 cetaceans a year and is now scheduled for closure by the European Commission. This is causing anger among fishermen, who point to the possibility of using "pingers" to keep the dolphin catch down. Despite this example of closure of a fishery that failed to acknowledge and address ecological impacts until too late in the day, there has been little sign that the lesson has been learned by the midwater trawling industry which also has a major dolphin by-catch. Very small drift nets are used for herring on the north coast of Devon, where fishermen set the net upstream of tidal races and drift through them alongside the net. Fishermen there have watched porpoises fishing along the net, using it as a barrier to control their prey!
Netters and other static gear fishermen have a problem with trawlers which may tow away their gear without even feeling a tweak, while trawlers see static gear as creating unwelcome exclusion zones.
Trawling uses trawls - bag-shaped nets which are towed through the water. Pelagic trawls are the same as midwater trawls and can be pulled by one or two boats. Pair trawling enables boats to pull larger nets - some of them with openings half a kilometre across. The French pelagic trawl fishery for bass in the Channel, western approaches and Biscay coast has attracted Scottish boats in recent years and has been one of several pelagic trawl fisheries catching dolphins. The winter strandings of dolphins on French and south-west English coasts have reached over 600 and 100 respectively in some years and are mainly due to this form of trawling, although they can show no external damage, even under expert inspection.
Cornwall Wildlife Trust Page 14 Wild Cornwall - No. 83 Autumn 2000
Pair trawl (large enough to hold 12 jumbo jets)
Wild Cornwall the newsletter of the Cornwall Wildlife Trust
Issue 83 - Autumn 2000