Ecosystems are also suffering, with algal blooms, fish die-off and other ecosystem disruption driven by nutrient nitrogen pollution ('eutrophication').

Subject to scientific advice and without jeopardising the objectives of maximum sustainable yield or increasing fishing mortality, where the landing obligation, including the obligation to document catches, applies, an increase of related fishing opportunities should be possible, in order to take into account the fact that fish previously discarded will be landed.

However STECF concluded that, based on the fact that such gears operate by trapping fish inside a static netting structure, as opposed to entangling or hooking for example, it may be reasonably assumed that mortality for these gears will be low.

The containment area must have been defined on a case-by-case basis taking into account factors influencing the risks for the spread of the listed disease to farmed and wild fish, such as: the number, rate and distribution of the mortalities of fish on the farm infected with either VHS or IHN or both; the distance and density of neighbouring farms; the proximity to slaughterhouses; contact farms; species present at the farms; the farming practices applied in the affected farms and in the neighbouring farms to the affected farms; the hydrodynamic conditions and other factors of epidemiological significance identified.

- by direct mortality on stocks of fish such as sandeels which are used predominantly for the production of fishmeal and fish oil to leave in the sea greater quantities of food for species occupying higher trophic levels, be they fish, birds or marine mammals, or;

- by direct mortality on fish stocks of value for human consumption (e.g. areas of concentrations of adult fish when spawning, or of a high incidence of juvenile fish, crustaceans and molluscs) thereby enhancing the probability of rebuilding or maintaining spawning stock biomass of such species or;