Sharks, together with skates and rays, make up the subclass Elasmobranchii of the class Chondrichthyes, cartilagineous fish; they represent less than 5% of marine fish species. Sharks are an ancient class of fish that first appeared about 400 million years ago and have remained virtually unchanged for the past 70 million years while being a dominant animal group. Their success is largely due to the original genetic traits they inherited from their more primitive ancestors. This gives sharks unique adaptations allowing them to occupy some varied ecological niches. At present, there are about 370 species of sharks described, approximately 80 of them are endangered. There are eight orders of sharks and species belonging to 5 of them are found in the Mediterranean Sea. The most represented is the Carcharhiniformes or ground sharks, including blacktip reef sharks, blue sharks, and hammerhead sharks. Elasmobranchs are generally considered commercial species, except for the basking shark (Cetorhinus maximus) and the white shark (Carcharodon carcharias) that are fully protected from all fisheries. For other species of Elasmobranchs quotas are set in some northern European fishing areas. Read More.
Due to their common life-history characteristics of slow growth, delayed maturity, long life spans, and low fecundity, sharks are highly sensitive to anthropogenic threats, and fishing impact in particular. In case of sharks species targeted in our research project (Mustelus mustelus, Mustelus punctulatus, Squalus acanthias), no information exists on their demography and population dynamics in Adriatic Sea. Nevertheless, they are heavily exploited, with catches ranging in hundreds of tonnes, and without any national management strategy. Field research in our project is focused on the northern Adriatic waters, from the western coast of Istria to the Zadar archipelago. Material is collected by on-board observers and in fish landings in selected ports. Field work includes collection of data for catch per unit effort analysis, temporal and spatial distribution analysis and sampling for laboratory analysis. Specimens of sharks taken for consumption and discarded are analysed for developmental and population biology traits such as age, somatic growth, age-at-maturity, reproductive biology, and ontogeny of gonads. The project additionally addresses comparative analysis on: diet composition and composition of helminth parasites in targeted shark species. The data will be used to create population models for the species and to assess species vulnerability to varying exploitation/bycatch rates, applicable for planning a conservation management strategy in Croatia.