Infection prevalence and pathology of the cymothoid parasiteOlencira praegustatorin Atlantic menhaden

Isopod parasites in the family Cymothoidae can cause reduced growth, castration, or even mortality in their hosts.Olencira praegustatoris a cymothoid that parasitizes the mouth and gill chamber ofBrevoortia tyrannus(Atlantic menhaden), which is the basis for the largest fishery along the eastern coast of the USA and an important link within estuarine food webs. To better characterize interactions betweenO. praegustatorandB. tyrannus,including parasite-induced pathology, we sampled hosts and parasites from three estuarine sites on Kiawah Island, South Carolina. Over 5 weeks, we collected, measured, and weighed 169 juvenile menhaden; remarkably, 96% of these fish were infected withO. praegustator,typically with one isopod found in the mouth of each host. Based on the external morphologies of 163 examined isopods, 58 were female (35.6%), 9 of which were gravid, and 105 were male (64.4%). Although fish size was unrelated to isopod length or mass, isopod length was a direct predictor of the amount of damage observed on the host operculum, which in severe cases involved tissue atrophy and hemorrhage. Considering the high infection prevalence, significant damage associated with infections, as well as the impairing effects of other cymothoids on their hosts, the consequences of interactions betweenB. tyrannusandO. praegustatorwarrant additional investigation for understanding the management and ecology of Atlantic menhaden.