Diet of the spothead lanternfish Diaphus metopoclampus (Cocco, 1829) (Pisces: Myctophidae) in the central Mediterranean Sea

The feeding habits of the bathypelagic, non-migratory myctophid Diaphus metopoclampus from a shrimp fishing ground area in the Strait of Sicily were analyzed. Overall, 296 adult specimens ranging from 50.8 to 92.8mm standard length (SL) (mean SL=72.9 +/- 8.0mm) were collected during two trawl surveys (October 2010 and May 2011) and their stomach contents were examined in order to provide new information on prey composition and feeding strategy of this poorly known lanternfish. Differences in diet depending on fish size and time (daylight and night) were also checked by statistical analysis. D. metopoclampus is a zooplanktivorous predator, consuming mainly Crustacea, but also Mollusca, Polychaeta, Chaetognatha, Taliacea and Actinopterygii, and showing a moderate opportunistic feeding strategy. D. metopoclampus can be ascribed to the group of acyclic predators, since it seems to be a non-migrator myctophid that feeds when prey are available. Statistical analysis indicated a size-related shift in the diet of D. metopoclampus from smaller prey organisms (e.g, Metridinidae) to larger ones (e.g, Euphausiidae and Myctophidae). Some differences in prey composition between daylight and night were highlighted: euphausiids and myctophids were more abundant during night, Metridinidae during daylight.