ADVICE NOTE : MARINE FISH FARMING AND THE ENVIRONMENT

husbandry and management

disease and parasite transfer

68. Disease can be transferred by fish coming into physical contact with each other, or by the transmission of pathogens through the water medium. The movement of micro-organisms in coastal waters depends on currents which may be erratic. It can therefore be difficult to predict where pathogens, entering the water at a particular point, will end up.

containment

69. While the incidence of mass escape (or deliberate liberation) of farmed fish is low, the industry recognises the risk and the need for constant vigilance if it is to be minimised. Even small stock losses are taken seriously by fish farmers and their associations. The consequences of escape can be economically devastating as well as having wider, long-term repercussions for fish populations and associated fisheries. As a result the Scottish Executive, in association with both the industry and representatives of wild migratory fisheries, is developing a code of practice on containment which will be supported by site specific contingency plans to effect recapture should escapes occur. The code of practice will be underpinned by a mandatory legislative requirement to notify escapes.

separation

70. In inshore areas the maintenance of adequate separation distances will greatly reduce the risk of adverse interactions between marine fish farms and the potential for conflict with other interests. The indicative spacing standards devised by the Crown Estate for the western seaboard reflect the concerns of existing fish farmers about disease transmission, water pollution and the risk of service vessels causing damage to equipment, as well as the need to safeguard visual amenity, wildlife, established anchorages and fishing grounds. While the specified distances are inevitably somewhat arbitrary in nature, there is a widespread consensus that they play a valuable role in minimising the potential for conflict.

71. The separation distances below (page 16) were developed by the CEC more than 10 years ago. They are reproduced here for guidance but should not be regarded as absolute. In all cases a careful assessment of hydrography, topography and local interests will be necessary. It is not possible to provide meaningful advice in respect of separation distances from rivers hosting freshwater pearl mussel, salmon and sea trout populations as local factors will vary between sites however local authorities should bear in mind the need to protect freshwater biodiversity when considering applications in close proximity to mouths of such rivers.

Fallowing & Management Agreements

72. The marine phase of salmon farming operates on an 18-24 month production cycle and generally to break potential disease cycles or site souring, there is a growing tendency amongst fish farmers to stock sites with a single year class of fish and to fallow sites between restocking. These are practices to be recommended: similarly, in order to eliminate the risk of disease transmission between first and second year fish, adopting rotational systems of management, usually involving two or more sites.

73. To minimise the risk of cross-infection and other adverse interactions between marine fish farms, close liaison between neighbouring operators is essential. The growing co-operation between salmon farmers over the siting of cages is a welcome trend within the industry. Another approach which yields positive results where units are in relatively close proximity is the use of management agreements between operators whereby their individual operational practices are harmonised to reduce the possibilities of harmful interaction. Experience indicates that inter-company agreements on fallowing, stocking densities, year-class separation and medication have produced mutual benefits to operators and reduced adverse environmental effects. In addition such agreements provide associated benefits for wild fisheries and this is reflected in a the growing trend of management agreements between salmon farmers and wild fisheries interests.

74. These benefits are endorsed by the Joint Government/Industry Working Group on Infectious Salmon Anaemia established to review current practices within the fish farming industry, to identify those risks which might pose a threat in the spread of ISA and the measures to be taken to reduce those risks. The Groups second interim report recommends the establishment of hydrographically defined management areas for the aquaculture industry the purpose of which are to ensure that day to day operations such as restocking, fallowing, disease treatment and harvesting are co-ordinated in such a way as to minimise the spread of disease and sea lice between Management Areas. This report has been circulated widely for comment and further work needs to be done before the proposals are adopted. However, the founding principles represent a sound basis for sustainable development of the industry.

75. Details of proposed management arrangements should be included in lease applications so that consideration can be given to their implications for the environment and local infrastructure.

Indicative Separation Standards

New Species

76. The equipment, management techniques and site characteristics required for the farming of new species may be different from those required for established species and their commercial production may be subject to different constraints. For example, the Sea Fish Industry Authority has recently undertaken trials to determine the potential for intertidal clam cultivation and is currently engaged in research to develop equipment and techniques suitable for the farming of halibut and cod.

77. The release of non-native species into Scottish waters is carefully regulated to prevent ecological damage and the introduction and spread of serious pests and diseases. The introduction of exotic species into the wild requires a licence from SERAD. Scottish Natural Heritage also has powers to control the introduction of species under the Wildlife and Countryside Act 1981 and is consulted by SERAD before a licence is granted.