Chemicals from Marine Fish Farms

Monitoring of chemicals from marine fish farms in Nordic environments - veterinary medicines, biocides and persistent organic contaminants

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Fish from Nordic fish farms have been criticized for containing "too high" concentrations of persistent organic pollutants (POPs) among others dioxin and PCB. These allegations have caused debate and may have a negative effect on the sale of products from Nordic fish farms in addition to giving a generally bad reputation that affects more or less all Nordic fish farms. It is generally agreed that the relatively high concentrations of POPs detected in fish from Nordic fish farms are caused by the high concentrations of POPs in the fish feed produced and used in the Nordic countries. Beside potential health effects caused by high POP contents in the fish fillet, the surrounding environment may be impacted as well, not only by excreted POPs but also by veterinary medicines used in the fish farms. In Nordic fish farms, veterinary medicines are mainly used therapeutically against different infectious diseases. The amount of veterinary medicines used varies from year to year and in some years, considerable amounts have been used. The major environmental concern in relation to the use of veterinary medicines is the potential occurrence of antibiotic resistance in the naturally occurring micro flora.



Development of recommendations for environmental monitoring programmes for veterinary medicines, help substances and persistent organic pollutants in Nordic fish farms including identifycation of relevant indicators

The environmental monitoring around fish farms includes a very limited set of pollutants mainly restricted to nutrients and selected metals. A pilot study performed as part of the present assessment included a range of unintentionally added pollutants such as persistent organic pollutants, dioxin and oil-derived pollutants as well as intentionally added antibiotics. Analyses of this kind are expensive and may not be justified as parts of a regular monitoring scheme. The study revealed however, that certain pollutants correlated and it may thus be possible to choose a “cheap” parameter as a proxy for a more expensive one. This simplified monitoring would necessitate an initial study to ascertain inter-pollutants correlations because the dominant sources of pollutants will depend on the origin and composition of e.g. the fish feed and are not necessarily the same from one fish farm to the next. In addition, and quite important, monitoring that complies with the EU water framework directive may comprise the majority of pollutants associated with fish farming especially those unintentionally added to the environment. On the other hand, therapeutic agents will not be monitored in such a scheme but requires a specific effort - first of all, assessment of the magnitude of the potential impact by measurements of the concentrations of the therapeutic agent in the environment and risk assessments of ecosystem effects.


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