Application of serological methods to identification of fish prey in diets of seals and dolphins

The present paper demonstrates the application of serological methods to the identification of fish prey in the diets of marine mammals. Antisera were raised to muscle protein extracts of cod Gadus morhua Linnaeus, herring Clupea harengus Linnaeus and salmo salar Linnaeus. The antisera were tested for reactions with protein extracts from raw and in vitro digested fish muscle; stomach contents of captive dolphins Tursiops truncatus Montagu fed on known diets; digestive tract contents of seals Halichoerus grypus Fabricius and Phoca vitulina Linnaeus which contained hard remains of known prey species; and faeces of captive seals fed on known diets. The salmon antisera were shown to be sufficiently strong and specific to be used for identification of salmonid proteins in digestive tract contents of marine mammals, and were potentially applicable to screening seal faeces. Antisera raised to cod and herring were less successful, due to low specificity and low titre, respectively. The potential exists to develop this methodology for routine identification of a range of prey species in marine mammal diets.