A parasitological survey of Galeus melastomus Rafinesque, 1810 from deep waters of the NW Mediterranean sea in relation to diet and health condition of the host

Abstract

9th International Symposium on Fish Parasites (ISFP), 31st of August to 4th of September 2015, Valencia, SpainDespite their importance and vulnerability, deep-dwelling elasmobranchs are still poorly understood. In this context, this study aims to perform a parasitological survey of the blackmouth catshark Galeus melastomus Rafinesque, 1810 in deep waters of the north-western Mediterranean Sea describing variability on the parasite community between host maturity stages and its relation to diet and health condition of the host. A total of 120 specimens of G. melastomus were captured in 2010-2011 at 400-1,400 m depth in three different locations of the Balearic basin using a semi-balloon ottertrawl. Parasitological, dietary, enzymatic stress indicators and histological data were obtained according to standardized protocols. Main relationships among fish parasite load, size, condition indices, enzymatic activity of muscular acetylcholinesterase, lactate dehydrogenase and citrate synthase and intensity of hepatic melano-macrophages were tested. A total of 16 different parasite taxa were found: one coccidian, one monogenean, one digenean, five cestodes, seven nematodes and one copepod. The most important parasites in terms of prevalence and abundance showed a significant relationship with host size, probably reflecting hosts ontogenic diet shifts: the digenean Otodistomum sp., the cestodes Scolex pleuronectis and Grillotia cf. adenoplusia and the copepod Eudactylina cf. vilelai were linked to adult sharks, while the cestode Ditrachybothridium macrocephalum characterized juvenile hosts. Overall results considering associations between parasite infection parameters and health condition of their hosts yield the conclusion that, in the present study, the intensity of parasite infections does not negatively affect fish health.The study was supported by the MICINN project ANTROMARE (CTM2009-12214-C02-02)Peer Reviewe