Herons accused of poaching at fish-farms

In Britain, helium-filled kites are deployed to keep the marauding birds off fish-tanks

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By Matti Huuskonen in Virolahti
     
      At around 8 p.m. they arrive. Grey herons, landing in the trees on the shore of the island of Tuuholma. They hole up there for a couple of hours, and then glide across to the fish-farm pools in front of the island.
      The nets strung across the pools, which belong to Kellosalmen Lohi, a local fish-farm, sag under the weight of the alighting birds and drag in the water.
     
The well-designed bill of the grey heron (Ardea cinerea) goes into action: one darting downward action of the long neck, one sharp blow into the flank of a young whitefish, one swallow.
      Repeat at leisure until the early hours of the morning.
      "They tend to go for the whitefish rather than the rainbow [trout], which has a tougher skin", says Seppo Tilli, who lives onshore in Virolahti and is the co-owner of the fish-farm with his brother, Veli Tilli.
     
Grey herons have become an increasingly common sight in Finland over the past couple of decades.
      According to Birdlife Finland's Margus Ellermaa, the nesting population at the turn of the millennium was between 200 and 400 pairs. It is likely this figure has increased since then.
      The Hamina ornithologist Seppo Grönlund estimates that the nesting population in the Kymi Valley area of the south-east of the country is around 50 pairs. After the nesting season, which ends in July, there can nevertheless be as many as 500 individuals in this part of the country.
      Perhaps because of the rich pickings hereabouts, the region's densest population, and possibly the greatest concentration in the whole country, is located at Vilkkiläntura, a shallow silted bay with reedbeds, and around the Tilli brothers' establishment.
     
The Tillis have noticed they are living in "heron country".
      "This is the fourth year they've been going at the pools. The worst was last year", says Seppo Tilli.
      "It's a protected bird, and by no means cheap to eliminate", he goes on.
      It is not only that the herons eat the smaller, younger fish, they also injure the ones that get away. The gashes made by the birds' beaks become infected, and the fish die.
      Teemu Tast, executive director of the Sea Fishing Association of Southern Finland, regards the grey heron as a growing problem, but thus far only as a local issue. It is specifically the Virolahti hatcheries and fish-farms that are suffering.
     
Tast mentions a few alternatives that might alleviate the problem.
      Tougher and thicker nets over the ponds are one way to go. In Britain, herons have been scared off using giant helium-filled kites, while in Norway permits have even been granted to shoot the trespassing birds.
      Bird enthusiasts naturally do not take kindly to the thought of bringing firearms into the equation: "They should simply put out the sort of nets that ensure the birds cannot reach down to the fish", argues Seppo Grönlund.
     
Helsingin Sanomat / First published in print 20.8.2005


Links:
  Grey Heron (Ardea cinerea) in Birds of Britain

MATTI HUUSKONEN / Helsingin Sanomat
matti.huuskonen@hs.fi