Spring Carp Mortality Syndrome Project

Over the last 10 years there has been growing concern about unexplained large-scale carp mortalities which generally occur in spring in fisheries throughout England and Wales. These mortalities have become known as Spring Carp Mortality Syndrome (SCMS).

Following a two year project designed to collate data related to SCMS incidents and to investigate the primary cause of the syndrome, which was undertaken by the Environment Agency in conjunction with the Centre for Environment Fisheries and Aquaculture Science (CEFAS), it appeared that an infectious agent was likely to be underlying the mortalities. However a specific pathogen was never identified.

Current efforts supported by the English Carp Heritage Organisation (ECHO), the Environment Agency and CEFAS have involved re-examining data collected during previous investigations to get a better understanding of events and to provide an indication of high risk activities. The main aim is to determine whether an infectious agent is responsible for this syndrome and if so, to identify it. Ongoing research by CEFAS will involve the development of molecular tests for viruses that can be used to test samples from historic and future SCMS events. Although the exact nature of the agent is still unknown, the well-known fish virus Spring Viraemia of Carp (SVC) has been ruled out.

As part of the Environment Agency’s normal monitoring of fish mortalities in the wild, the Agency will be placing particular emphasis on potential SCMS cases this year to support the ongoing work. SCMS events typically involve only common carp (and varieties such as mirror, leather and ghost carp, etc), occur between March and August and result in a sudden increase in dead fish over a short period of time. Symptoms associated with SCMS events may include excess mucus production, gill necrosis, lesions, osmoregulatory problems and behavioural changes (lethargy).

The Environment Agency would like to take this opportunity to remind fishery owners that they should always report fish mortalities on their waters. As well as investigating for possible disease, Environment Agency officers can also provide advice to fishery owners to prevent problems in the future.

The Environment Agency and CEFAS are pleased to be receiving support from ECHO in moving this project forward.

Recommendations

One of the outcomes of the initial project was a number of recommendations to fisheries managers to avoid or mitigate the effects of SCMS.

• Avoid stocking carp to waters that already hold an established carp population. Over half of the studied SCMS cases had received a recent introduction of new fish. If possible increase the natural productivity and improve the habitat of the water to promote natural recruitment.

• Disinfect all equipment that comes into contact with the water. Iodophor based disinfectants are effective if used correctly. Carefully drying fishing tackle, nets, etc. and exposing to direct sunlight also has a sterilising effect.

• If a mortality incident occurs stop fishing. This will reduce the stress on the fish and allow the immune system the best chance of fighting the disease. This action would also reduce the risk of spreading an infectious agent to other waters.

• Talk to your local Environment Agency Fisheries Officer. They are able to provide advice and help

Note to editors

The Environment Agency has a duty to maintain, improve and develop inland fisheries. The Agency regards investigating fish disease outbreaks and providing advice to fisheries managers to prevent repeat problems as being a significant aspect of this duty.

Fishery owners, under the Diseases of Fish act 1937 as amended, have a legal duty to report any suspicion of a notifiable disease outbreak to DEFRA (through the CEFAS Fish Health Inspectorate). By notifying the Environment Agency they will fulfil this duty, as the information will be forwarded by the Agency.

For further information please contact Jane Snow on 01480 483019 or
jane.snow@environment-agency.gov.uk