Marine: Cleaner Seas report
Threats to life at sea
Fisheries
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The fisheries of the North East Atlantic are managed within the European Community's Common Fisheries Policy. Each year the UK Government helps to establish limits on the quantity of fish which may be caught, so that enough fish are left to spawn and provide the future harvest. These limits are based on international scientific advice, to which the UK makes a major contribution.
Many important fish stocks have been subject to intense fishing since the beginning of the 20th century.
Changes in these fish stocks can generally be explained in terms of either natural factors and/or fishing intensity.
Trends vary considerably from species to species. The North Sea herring population was seriously affected by over-fishing in the 1970s and the fishery was closed between 1978 and 1982, allowing stocks to recover.
Herring stocks have declined again since the peak in the mid-1980s and emergency measures were taken in 1996 to prevent closure of the fishery.
North Sea cod stocks have declined since reaching a peak in the late 1960s, and stocks are currently about two thirds of the average level in the 1970s. North East Atlantic mackerel stocks have declined since 1992.
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Controlling catches is achieved by setting annual quotas and by applying rules for mesh sizes, landing sizes and areas closed to fishing. It is hoped these measures, together with measures to reduce fishing effort, will help to maintain marine fish stocks to ensure that fishing remains a viable industry.
Stocks of salmon and sea trout are affected by climatic and environmental factors during both their freshwater and marine phases. Although it is difficult to control such factors, steps have been taken to limit exploitation at sea and in rivers. Improvements to habitat and water quality have led to salmon returning to rivers such as the Thames and the Tyne.
Fish nursery grounds in the eastern North Sea such as the Wadden Sea on the Dutch coast have been affected by high levels of pollutants. An example of a particular contaminant which has affected a variety of UK marine species, including commercial shellfish, is Tri-butyl Tin (TBT) used in marine anti-fouling paints. The use or sale of this is now prohibited for boats under 25 metres with corresponding improve-ments in the marine environment.
The IMO is considering a proposal that a ban on the use of anti-fouling paints containing TBT should be implemented for all ships from 2006. The UK supports this proposal.
Through the Sea Mammal Research Unit (SMRU), the Fisheries Departments have established a scheme to acquire data on animals accidentally caught in fishing nets. As many of the animals found in British waters are part of wider populations, it is necessary for such work to be carried out through collaborative research.
When available, this information will help to identify the extent of interaction between commercial fisheries and small cetaceans and the problems this causes.
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Page last modified:
01 March 2005
Page published: 21 September 1988