Many of the fish mortalities investigated by us reveal that the over-riding cause of the mortality was associated with poor fisheries management
The losses incurred by a mortality on a fishery can be highly damaging, both in terms of the financial cost of replacing the fish stock or lost income from visiting anglers and in terms of ecological damage. Therefore, it is important to safeguard against the chance of an avoidable mortality occurring.
Many of the fish mortalities investigated at the National Fisheries Laboratory reveal that the over-riding cause of the mortality was associated with poor fisheries management. Therefore, it is recommended that you seek advice from either your local Environment Agency Fisheries Officer or a fisheries management professional on the best way to manage your fishery.
The advice provided will include the preferred species of fish to introduce, the optimum density of fish to have in the fishery and any habitat enhancements that you can do to the fishery to ensure the fish remain healthy.
During a mortality investigation, we are looking for what is causing the fish to die. This involves a full post-mortem and includes taking samples for bacteriology (is a bacterial infection killing the fish?) and histology (looking for damage in tissues at a microscopic level). Once the cause has been ascertained, advice will be provided to hopefully prevent the loss of any more fish and management actions that can be taken to ensure it cannot happen again.
Should the cause of death be a notifiable disease such as SVC (Spring Viraemia of Carp), then CEFAS (efishbusiness.co.uk) will be notified and they will investigate the mortality further.
If you are experiencing losses on a water you own, manage or simply fish then please contact your local Environment Agency office immediately.
We have produced a set of fact sheets to provide the basic information that can help prevent fish disease outbrakes in your fishery. They cover the management of habitat, water quailty, fish stocks and fish introductions. Should a disease outbreak occur, they explain what to do if fish are dying and how to help your fishery recover afterwards.
Each fishery is unique, so these fact sheets can only provide an overview. You should always seek specialist advice.
Fact sheets in the Fish health and fisheries management series