Publication Abstract

Pathogen hazards associated with the import of predator baitts to the UK

E.J. Peeler and F. Pearce

The use of angling bait is recognised as a potential pathway for the introduction of pathogens and parasites into aquatic environment but the bait industry is largely unregulated. Fish baits, both marine and freshwater species, are popularly used in angling for large predators. The use of predator baits is potentially an important route of disease introduction as the fish are often used whole and come into direct contact with susceptible species. Businesses supplying predator baits were contacted and a list of bait species compiled. The most popular bait species are lamprey, smelt, mackerel, sprat and herring. Freshwater species such as eel, perch, roach and trout are also used. One supplier of predator baits advertised eels as coming from sustainable sources, as they are mortalities from aquaculture. In addition, rainbow trout intended for human consumption may be diverted for use in freshwater angling.

Disease hazards (for freshwater fish species in the UK) associated with imported bait species used were identified, i.e. pathogens or parasites that are absent from the UK or with limited distribution, OIE listed or a significant threat, and able to withstand freezing (predator baits are sold frozen). The most important hazards identified were viral haemorrhagic septicaemia virus (VHSV), infectious haematopoietic necrosis virus (IHNV) and eels pathogens (eel herpesvirus and rhabdovirus). The persistence of VHSV in the tissues of infected trout has been demonstrated. Whilst the major pathogens of eels have been detected in the UK, their distribution may be restricted. The use of imported fish as bait in freshwater angling is a potentially important route of disease spread since it creates direct routes for the exposure of susceptible wild populations. The use of mortalities from aquaculture is particularly worrying because the animals are highly likely to be infected, and it provides a route for establishment and spread of new pathogens. The introduction of VHSV and IHNV (through diversion of imported trout for use as bait) and eel pathogens need to be investigated further in an import risk analysis to support strengthened biosecurity.