ARCHIVE: Veterinary surveillance: Fish
This page gives a brief introduction to fish and shellfish farming in the UK and explains how we look out for diseases of fish. It also has some information on the UK fishing industry, angling and the keeping of ornamental fish. It has links to other pages on the Defra website. You can find further information on other websites by using the link at the bottom of this page.
Fish and shellfish farming
Fish farming is defined as the keeping of live fish with a view to their sale or transfer to other waters. This also applies to salt and fresh water shellfish. Fish may be farmed for food or for stocking fisheries such as ponds, lakes and rivers for anglers.
There are over 1000 fish and shellfish farming businesses in the UK. They lie mainly in the inshore waters of the west coast and Western and Northern Isles of Scotland. The most common species of farmed fish are salmon with nearly 140,000 tonnes produced in 2001. Salmon production takes place in both freshwater and seawater. Young salmon are reared in freshwater for 6 to 14 months, where they undergo certain changes, called smoltification, that prepare them for the seawater phase of their life. They are then transferred to sea cages. Some farmers now produce other marine finfish in much smaller amounts, for example cod, turbot and halibut. The other important farmed species (rainbow trout, brown trout and carp) are farmed in freshwater throughout the UK. Rainbow trout are produced both for the table and for stocking recreational fisheries. Brown trout, carp and other species, such as roach and chubb, are farmed almost entirely for recreational angling. Shellfish are cultured principally on the seabed or on trestles, or suspended on ropes or in nets. The most common shellfish farmed are mussels. However oysters and clams are also farmed.
All fish and shellfish farmers in England and Wales must be registered with Defra or NAWAD, in Scotland with the Crown Estate and in Northern Ireland with the Department of Agriculture and Rural Development. This helps to control the introduction and spread of diseases from farmed fish to wild stocks. Records have to be kept of all movements of fish and shellfish both to and from sites.
UK fishing industry (Sea Fisheries)
The management and conservation of sea fisheries is concerned both with conserving fish stocks and their habitat, and with minimising the impact of commercial fishing on other species and their habitats. In the UK the number of fishermen and fishing vessels has been gradually decreasing. Fish stocks have been depleted and their management and conservation is now co-ordinated by the Common Fisheries Policy. In the EU in 2004 there were approximately 82,500 fishing vessels, with 8% of these sailing out of UK ports.
A Total Allowable Catch (TAC) is set by the Council of Ministers for the EU each year and these are allocated as quotas to Member States.
In the year 2004 some 654 thousand tonnes of sea fish were landed in the UK and abroad by the UK fishing fleet. Just over a third of these were demersal species (fish that live on or near the sea bed), such as haddock, cod, whiting and plaice. Pelagic species (fish living in shoals in midwater or near the surface of the sea) such as herring and mackerel accounted for almost half of the catch. The catches of shellfish, including crabs, lobsters, langoustines and scallops, have increased and now make up a fifth of the UK fleet’s landing.
UK Fishing industry (Inland and River Fisheries)
Angling is a very popular pastime in the UK with more people going fishing than participating in any other sport. In Scotland alone there are more than 30,000 lochs and smaller ‘lochans’ and over 35,000 km of rivers. Inland fisheries are valuable natural assets and the numbers of fish present are indicators of the health of the freshwater environment. Any decrease in numbers of migratory species (such as salmon coming back to the rivers where they were born to spawn) may show up possible problems in the oceans. A decline in numbers of migratory fish has been noted throughout Europe with various suggested causes including climate change and effects from fish farming and marine fisheries. However, work carried out by the Environment Agency on fisheries in England and Wales has shown an increase in coarse fish in many rivers. Also many anglers fish entirely on stillwaters, which are stocked to provide good catches.
The Freshwater Fish Directive is concerned with the protection and improvement of fresh waters in order to support fish life and ensuring the protection of fisheries.
Ornamental fish may be kept in aquaria or garden ponds. Tropical fish need the warmth and protection of an aquarium, but there are numerous varieties of cold water fish such as goldfish and carp, which will live and thrive in garden ponds. Surveys carried out by the Ornamental Aquatic Trade Association (OATA) have estimated that in the UK, approximately 3 million households have either a pond or aquarium with fish. This would make fish the third most popular pet in the UK after cats and dogs. The estimate of numbers of ornamental fish kept in the UK range from 25 to 140 million, with exact numbers not known.
Looking for fish diseases
There are various checks and controls used to prevent the spread of disease outbreaks and in combating fish diseases. These ensure that only healthy fish come into the country and that if there are outbreaks of serious disease we can act quickly to reduce their impact. All fish farms are regularly monitored to check for the presence of disease.
In England and Wales the monitoring and testing under the fish health controls is carried out on behalf of Defra and NAWAD by the Fish Health Inspectorate (FHI) at the Centre for Environment, Fisheries and Aquaculture (CEFAS) in Weymouth. In Scotland this is done by the Fisheries Research Services in Aberdeen, an agency of the Scottish Executive Environment and Rural Affairs Department (SEERAD) and in Northern Ireland by the Department of Agriculture and Rural Development (DARDNI). The Environment Agency carry out investigations into fish numbers and water quality, which may give an indication of the overall health of the fish population.
The Institute of Aquaculture in Stirling is involved in the investigation and diagnosis of diseases of fish, both for commercial fisheries and fish farms and as a service to private veterinary surgeons and their clients. The Veterinary Laboratories Agency and Scottish Agricultural College will also do some diagnostic work on fish.
There are also many private veterinary surgeons who are interested in fish disease and management.
Which are the most important diseases of fish in the UK?
Different diseases are important to different groups of people. From the point of view of the Government, the most important infectious diseases of fish that continue to appear in the UK are probably bacterial kidney disease (BKD) and furunculosis and infectious pancreatic necrosis (IPN) in salmon. From the point of view of the salmon farmer, other very important conditions are both sea and fresh water lice, salmon pancreas disease and cardiomyopathy syndrome. The most important diseases affecting farmed trout include proliferative kidney disease (PKD), furunculosis, enteric redmouth (ERM), rainbow trout fry syndrome (RTFS) and white spot. Many outbreaks of disease in aquarium and pond fish are associated with poor water quality or management conditions, which may cause stress to the fish.
What other diseases do we look out for?
We also keep a look out for fish diseases which do not usually occur in this country. The most important of these exotic diseases are infectious haematopoietic necrosis (IHN), viral haemorrhagic septicaemia (VHS), Spring viraemia of carp (SVC) and gyrodactylosis. News from other countries about these diseases helps us plan how to keep them out.
- Other websites - These sites may be useful if you are interested in further information about fish in the UK. Please note that Defra does not necessarily endorse the content, information or opinions of these sites.
- Fisheries information on the Defra website.
Page last modified:
4 May, 2010
Page last reviewed: 4 May, 2010