No abstract

In the present paper, recent results obtained on the use of different distributions observed in larval species of Anisakis, genetically identified by means of allozyme markers, for stock characterization of demersal (Merluccius merluccius), small (Trachurus trachurus) and large pelagic (Xiphias gladius) finfish species in European waters, are reviewed and discussed. Several species of Anisakis were identified in the three fish hosts: A. simplex (s.s.), A. physeteris, A. typica, A. ziphidarum, A. pegreffii, A. brevispiculata and A. paggiae. Canonical discriminant analysis performed on all the samples of the three fish species collected in areas comprising their geographical range, according to the different species of Anisakis identified, showed distinct fish populations in European waters. In all the three fish hosts, the pattern of distribution of Anisakis larvae allowed discrimination of Mediterranean stocks from Atlantic stocks. In the case of swordfish, the possible existence of a southern Atlantic stock separated from a northern one is also suggested. Congruence and discordance with the population genetic data inferred from allozyme markers on the same samples of the three fish species are also discussed.

Garcia, A., Mattiucci, S., Damiano, S., Santos, M. N., and Nascetti, G. 2011. Metazoan parasites of swordfish, Xiphias gladius (Pisces: Xiphiidae) from the Atlantic Ocean: implications for host stock identification. – ICES Journal of Marine Science, 68: 175–182. The metazoan parasite fauna composition of the swordfish Xiphias gladius is reported from 157 fish caught in four areas of the Atlantic Ocean: northwest (NW), central north (CN), eastern tropical (ET), and central south (CS). Samples were collected in 2003, 2006, and 2007. In all, 18 parasite taxa were identified by morphological and genetic methods. These data, together with earlier analyses from the tropical equatorial (TEQ) Atlantic revealed the association of some parasite taxa with distinct areas based on their presence/absence and infection levels. Hysterothylacium corrugatum (s.l.) and Rhadinorhynchus pristis were mostly associated with swordfish caught in the NW, and Anisakis paggiae and H. incurvum with fish caught in the southern areas (ET, TEQ, and CS). Anisakis simplex (s.s.) could be used as a marker for all northern samples. Parasitological data on Atlantic swordfish seem to support the existence of at least two discrete stocks in the Atlantic, supporting swordfish genetic stock structure.