Sharks

Shark catch on local trawler
Due to their common life-history strategy characterized by slow growth, delayed maturity, long life spans, and low fecundity, sharks are highly sensitive to anthropogenic threats, fishery impact in particular. In the case of sharks that are targeted with this 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 thons, and without any national management strategy.

Field research in our project is focused on the northern Adriatic waters, from the western coast of Istra to the Zadar archipelago. Material is collected by on-board observers and in contact with 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 discards are sampled for analyses of developmental and population biology:
(1) age determination
(2) somatic growth
(3) age-at-maturity
(4) reproductive biology
(5) ontogeny of gonads.

The project additionally addresses comparative analysis on:
(6) diet composition
(7) 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.