Experiments with the Harbour Seal, Phoca vitulina, a Definitive Host of a Marine Nematode, Porrocaecum decipiens

Abstract

Infestation experiments carried out in 1947 and 1948 showed that the harbour seal (Phoca vitulina) was a definitive host of a larval nematode found in the flesh of the Atlantic cod (Gadus callarias), smelt (Osmerus mordax), Canadian plaice (Hippoglossoides platessoides) and eelpout (Macrozoarces americanus). Adult worms recovered from experimentally infested seals were identified as Porrocaecum decipiens. Some larval Porrocaecum in the four species of fishes studied were P. decipiens.The worms lost their larval characteristics by moulting between the third and sixth day following introduction into the seal. Sexual maturation proceeded rapidly after the eleventh day and some males and females matured before the twentieth day. Maturation was accompanied by a distinct increase in size.