222. Fish farms can suffer considerable losses as a result of predator activity. The principal predators are seals, otters, mink, herons, cormorants, shags and other seabirds.
223. Methods of control include top netting of entire farms or net coverings for individual tanks and raceways in trout farms and similar top netting of sea cages. Tensioned cages can also be used to prevent access by predators in the water which attack the sides or base of the cage. However, these cages must be adequately tensioned and of a suitable mesh size to reduce the risk of predators becoming entangled. It is unacceptable deliberately to set nets so that predators are trapped and die. Predator damage can be prevented or reduced by scarers or shooting.
224. Many of the animals which prey upon farmed fish are themselves protected by law. All wild birds are protected by the Wildlife and Countryside Act 1981. Otters are protected by both the 1981 Act and the Conservation (Natural Habitats &c) Regulations 1994. Mink, whilst not specifically protected, may not be killed by certain methods laid out in the 1981 Act and the 1994 Regulations. Seals are protected during the closed (breeding) season by the Conservation of Seals Act 1970, and by the 1981 Act and the 1994 Regulations with regard to killing at all other times.
225. The killing of predators should be an absolute last resort and must be done within the constraints of the legislation protecting that species. Removal of individual animals will normally merely lead to re-occupation of the area by others, the major cause of predator presence being access to an abundant food supply. The primary objective of any action against predators should be physical exclusion or scaring.