Filling the Gap and Improving Conservation: How IUCN Red Lists and Historical Scientific Data Can Shed More Light on Threatened Sharks in the Italian Seas

Abstract

Chondrichthyans are one of the most threatened marine taxa worldwide. This is also the case in the Mediterranean Sea, which is considered an extinction hotspot for rays and sharks. The central position of the Italian peninsula makes it an ideal location for studying the status and changes of this sea. There is a lack of biological, ecological and historical data when assessing shark populations, which is also highlighted in the Red List of Threatened Species compiled by the International Union for the Conservation of Nature (IUCN). Historical data can provide important information to better understand how chondrichthyan populations have changed over time. This study aims to provide a clearer understanding of the changes in distribution and abundance of eight shark species in the Italian seas that are currently classified as at risk of extinction by the IUCN. In this respect, a bibliographic review was conducted on items from the 19th century to the first half of the 20th century, focusing on the selected species. The results show that all sharks were considered common until the beginning of the 20th century but have declined since, with a clear negative trend, mainly in the past 70 years. The strong local decline has been attributed to overexploitation, bycatch, habitat loss, depletion of prey items and environmental pollution. Furthermore, historical data also allow us to avoid the issue of a ‘shifting baseline’, in which contemporary abundances are assumed to be “normal”. Using historical data to further our knowledge of the marine environment is becoming increasingly common, and is fundamental in understanding human impact and evaluating mitigation measures to manage and conserve marine species and environments.

Improved Baited Remote Underwater Video (BRUV) for 24 h Real-Time Monitoring of Pelagic and Demersal Marine Species from the Epipelagic Zone

“…It is a highly invasive sampling technique as it involves species being injured or killed directly when caught or released. Stock depletion, overfishing, and by-catch have decimated elasmobranch populations in the Mediterranean [17][18][19], with most species caught as valuable bycatch in trawl and net multispecies fisheries [20][21][22]. Oceanic pelagic sharks are threatened by surface longlining targeting species, such as swordfish and tuna [23,24], worsening the situation of pelagic sharks, such as white sharks (Carcharodon carcharias) and blue sharks (Prionace glauca) [19].…”

An inventory of Bramble sharks Echinorhinus brucus (Bonnaterre, 1788) (Elasmobranchii, Echinorhinidae) in natural history collections worldwide for conservation status assessment

“…As a result, many sharks and rays are still listed as Data Deficient by the IUCN (Walls & Dulvy 2020; Dulvy et al 2021). In order to assess the conservation status of such species properly, the search and collection of other data sources by historical ecologists should be promoted, in particular sightings (Bland et al 2017; Leonetti et al 2020). Effectively, individual specimen records have proven useful in the past to document the occurrence of certain species at a specific locality and time (e.g.…”

Comparative Study of Semen Parameters and Hormone Profile in Small-Spotted Catshark (Scyliorhinus canicula): Aquarium-Housed vs. Wild-Captured

“…Among Chondrichthyes species, sharks, rays, and chimaeras are facing a global conservation crisis, suffering population decline and possible extinction due to factors such as overfishing, pollution, habitat destruction, and climate change [3][4][5][6]. Of the 1226 species of sharks and rays [7] and 52 chimaera species [8] in the wild, it is estimated that more than one-quarter are threatened according to IUCN Red List criteria, due to overfishing (targeted and incidental), habitat degradation, and other pollution threads such as heavy metals, microplastics, or endocrine disruptors [9][10][11][12][13]. Chondrichthyans are described as "apex predators", with few natural enemies and feeding on animals below them in the food chain, thereby stabilizing populations of other species [14] and playing a crucial role in the ecosystem [15].…”