Metazoan parasite infection in the swordfish, Xiphias gladius, from the Mediterranean Sea and comparison with Atlantic populations: implications for its stock characterization.
Bottom Line: A stepwise Linear Discriminant Analysis of the individual fish examined showed a separation among three groups: one including fish from the Mediterranean Sea (CTS, STS, and IOS); one consisting of fish from the Central South (CS), Eastern Tropical (ET), and Equatorial (TEQ) Atlantic; and a third comprising the fish sampled from the North-West Atlantic (NW); the CN Atlantic sample was more similar to the first group rather than to the other Atlantic ones.Finally, H. corrugatum, A. simplex (s.s.), Rhadinorhynchus pristis, and Bolbosoma vasculosum were related to the fish from the North-West (NW) Atlantic area.These results indicate that some parasites, particularly Anisakis spp. larvae identified by genetic markers, could be used as "biological tags" and support the existence of a Mediterranean swordfish stock.
Affiliation: Department of Public Health and Infectious Diseases, Section of Parasitology, "Sapienza" University of Rome, P.le Aldo Moro, 5, 00185 Rome, Italy.Show MeSH
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Mentions: When comparing the Anisakis spp. larval distribution in the Mediterranean fish with respect to the Atlantic Ocean samples, A. pegreffii was the dominant species in the Mediterranean Sea fish, while A. simplex (s.s.) was the dominant species in the North Atlantic samples; it occurred in coinfection with A. physeteris in North-Western (NW) fishing grounds; and with A. physeteris and A. brevispiculata Dollfus, 1906 in fish captured from the Central North (CN) area (Table 3). However, A. simplex (s.s.) was absent moving to the X. gladius fished in the Central South (CS), Eastern Tropical (ET) and Equatorial (TEQ) Atlantic fishing grounds (Table 3). Indeed, the fish from the last three sampling areas were found to be parasitized by the most abundant larvae genetically recognized as A. physeteris and A. brevispiculata (Table 3). These two Anisakis species were found in coinfection in these fish with two other Anisakis species: A. paggiae Mattiucci, Nascetti, Dailey, Webb, Barros, Cianchi, Bullini, 2005, and a taxon indicated as Anisakis sp. 2 (Table 3), genetically distinct from the other Anisakis spp. detected so far [27, 51, 52]. Moreover, the different species of Anisakis also showed significant differences in their infection levels in the Mediterranean swordfish versus the Atlantic Ocean samples (Table 4). The PCA analysis based on the distribution pattern and infection levels with Anisakis spp. from swordfish showed the Mediterranean swordfish samples clustering separately from the Atlantic ones (Fig. 2). In addition, according to the larval distribution of genetically identified species of Anisakis, in the Atlantic waters, a cluster formed by the “northern” samples, well distinct from the cluster including the “southern” samples, was observed (Fig. 2).Figure 2.
Affiliation: Department of Public Health and Infectious Diseases, Section of Parasitology, "Sapienza" University of Rome, P.le Aldo Moro, 5, 00185 Rome, Italy.