Updated Checklist of Chondrichthyan Species in Croatia (Central Mediterranean Sea)

SIMPLE SUMMARY: Relatively little is known about cartilaginous fishes (sharks, rays, skates, and chimaeras) in the Adriatic Sea. Still, many tons of these endangered animals are caught every year and not many protective measures are in place. How this exploitation affects their populations today, in the past and in the future is unknown. Our study outlines a list of all species known to occur in Croatia based on historical as well as new data. This updated information establishes a baseline for further research and can help policymakers make informed decisions on conservation measures for these fishes. ABSTRACT: Almost half of all chondrichthyan species in the Mediterranean Sea are threatened with extinction, according to the IUCN Red List. Due to a substantial lack of access to data on chondrichthyan catches in the Mediterranean Sea, especially of threatened species, the implementation of conservation measures is extremely insufficient. This also concerns the Adriatic Sea. Here we present a detailed and up-to-date assessment of the species occurring in Croatian waters, as the last checklist of chondrichthyans in Croatian waters was conducted in 2009. Occurrence records from historical data, literature and citizen science information have been compiled in order to present a comprehensive list of species occurrences. We found 54 chondrichthyan species between 1822 and 2022, consisting of a single chimaera, 23 rays and skates, and 30 shark species. Here, four additional species are listed but are considered doubtful. Five species are reported here for the first time for Croatian waters that were not listed in the survey from 2009. Nearly one-third of the species reported here are critically endangered in the entire Mediterranean Sea, based on the IUCN Red List. Additionally, we revisited the Croatian records of the sandtiger shark Carcharias taurus Rafinesque, 1810 and discussed its potential confusion with the smalltooth sandtiger shark Odontaspis ferox (Risso, 1810). Our results thus provide novel insights into the historical and current distribution patterns of chondrichthyan fishes in the Croatian Sea and provide a basis for further research as well as conservation measures.