Insights into the trophic interactions of the endemic shark Cephalurus cephalus: diet composition and first infection records of Anisakis and other nematodes

This study provides the first baseline information on the trophic interactions of the endemic shark Cephalurus cephalus through a multidisciplinary approach analyzing its diet, parasite component community, parasite diversity, and infection rates. Preys and parasites of 132 sharks caught off Magdalena Bay, Mexico, during June and July 2015 were identified and assessed ecologically adding new information on the behavior and interspecies interaction of C. cephalus . Diet of C. cephalus neonates, juveniles, and adults differed significantly. Individuals specialize on different prey types preying mainly on bentho-pelagic crustaceans, though the most important prey item was Pleuroncodes planipes (IRI 82.5%). The parasite component community was made up of larval stages of the nematodes Raphidascarididae, Ascarophis , Contracaecum , Anisakis , and Heliconema and adults of Mooleptus rabuka . Nevertheless, the infection was impoverished and mild from neonates to adults. Genetic evidence revealed the first infection by Anisakis berlandi and A. brevispiculata in a shark host. The encapsulated third stage larvae, impoverished abundance, and infection values of anisakids suggest that C. cephalus functions as facultative paratenic host for Anisakis spp. in open waters, though it serves as alternative final host for M. rabuka. Crustaceans and squids could potentially play different roles transmitting nematode species. However, the trophic link C. cephalus-Abraliopsis falco is proposed as a novel infection path for Anisakis spp. (redundancy analysis: R 2 = 0.61, F = 2.742, permutations n = 999, p = 0.05). These findings reinforce the carcinophagus feeding trend of C. cephalus and mild nematode infection. Anisakis berlandi is confirmed in the study area and reveals a trans-Pacific range of distribution for A. brevispiculata.