Organism and ecological impacts of electrofishing in Scottish shallow coastal habitats.

Over the last decade, electrofishing has developed in shallow marine coastal sites around Scotland. The principal targets are two species of razor clam (Ensis siliqua and Ensis magnus). These shellfish command high prices in the Far East which has driven a fishery that has increased substantially since the mid-1990s reaching a value of around £3 million per annum and extracting 400-500 tonnes of razors per annum. Electrofishing is preferred by the fishers because it produces a cleaner and hence more valuable product compared with other harvest techniques, such as dredging. It is also claimed that electrofishing is more benign from an environmental view but there is limited scientific evidence to support this. Some research has been conducted on the short-term impacts of electrofishing on razor clams and other non-target benthic organisms. These studies suggested that impacts are limited with razor clams being observed to rebury a few minutes after the electrical field has passed. Non-target organisms such as juvenile flatfish, starfish and crabs were either temporarily stunned or apparently unaffected. On the other hand there is anecdotal evidence that electrofished razor clams do not 'depurate'a as well as those harvested using other techniques. This suggests that electrofishing may affect the physiology of the clams in the short and possibly medium-term.

Although previously illegal under the EU Common Fisheries Policy, the Scottish Government has established a tightly controlled research-scale trial electrofishery for razor clams in a number of locations around Scotland. The impacts of the trial fisheries on the Ensis stocks are being monitored by Marine Scotland Science. However, concerns remain about potential longer-term impacts on both smaller and under-sized razor clams that are not collected, and on the wider benthic ecosystem, especially with industry pressure to open out wider areas to electrofishing.

The aims of the project will be to conduct laboratory and field-studies to address these issues.