Action: Translocate birds away from fish farms
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A study from the USA cited in a review found that translocating birds away from a fish farm appeared to reduce the number of birds at the farm. A study from Belgium found that translocating herons did not seem to be an effective way to reduce bird numbers at fish farms.
Studies detailing the effects of translocating birds (for many reasons) are discussed in a separate chapter. The two studies described below specifically deal with catching and releasing birds away from fish farms.
Supporting evidence from individual studies
A study cited in Mott 1978, effectively reduced a population of green herons Butorides virescens feeding at a fish hatchery in USA, by catching and releasing them 40 km away. No details are given regards the time period over which the reduced population level was maintained or the effort needed to catch the birds. The effects on fish farm productivity were not measured.
A study in Belgium found that capturing grey herons Ardea cinerea (using clap nets) at a fish farm and releasing them at various distances away (Van Vessem et al. 1985) did not appear to reduce heron abundance. Catching herons was very time-consuming (a maximum of four, but usually 1-2 caught each day). Some birds released 30 to 80 km returned within a month; one released 150 km away reappeared the following winter. Numbers relocated were too low to reduce heron abundance and relocation was considered ineffective.
- Mott D. F. (1978) Control of wading bird predation at fish-rearing facilities, In: Sprunt IV A., Ogden J.C. & Winckler S. (eds.). Wading birds, 131-132
- van Vessem J., Draulans D. & De Bont A. F. (1985) The effects of killing and removal on the abundance of grey herons at fish farms. Proceedings of the International Union of Game Biologists 17th Congress, 337-343