Infection of the lesser spotted dogfish with Proleptus obtusus Dujardin, 1845 (Nematoda: Spirurida) reflects ontogenetic feeding behaviour and seasonal differences in prey availability.

Proleptus obtusus Dujardin, 1845 is the most common parasite infecting the gut of the lesser spotted dogfish (Scyliorhinus canicula, Linnaeus). This nematode is trophically transmitted from an intermediate crustacean host to the definitive elasmobranch host. Sexual and age-related differences in habitat occupancy and feeding behaviour of the lesser spotted dogfish make this parasite-host dyad ideal for testing which aspects of host biology influence parasite transmission. Here, the relationship between P. obtusus burden and host condition, sex and age were investigated in lesser spotted dogfish captured in the Northeast Atlantic. Prevalence of P. obtusus was of 94.8% with a mean abundance of 23.3 worms per host. Our results indicate that parasite burden is best explained by the interaction between ontogenetic differences in foraging behaviour of the lesser spotted dogfish and seasonal differences in prey availability.