In the Gulf of Ognina off Catania, an adult bigeye thresher (Alopias superciliosus) died as bycatch. According to a report from the Italian animal portal Kodami, the animal got caught in the fishermen’s net and was brought to the surface already dead. Footage of the unusual catch then spread on social networks.
The video initially caused a stir because the shark was referred to as white shark. Shark expert Alessandro De Maddalena disagreed with this classification. Francesco Tiralongo, ichthyologist at the University of Catania, also classified the animal as bigeye thresher. The classification is based on the visible body features in the footage; an examination of the animal is not described in the report.
Large eyes, not a white shark
The angle in the video apparently obscured part of the most important feature: In thresher sharks, the upper lobe of the tail fin is exceptionally long and can almost reach the length of the rest of the body. The animals use this tail fin to stun schooling fish with quick strikes. The bigeye thresher also has the large eyes that give it its name and a distinctive groove on the head.
These characteristics do not match a white shark. The initial misidentification shows how cautiously individual mobile phone or video recordings must be assessed when fins are obscured and a reliable size reference is missing.
A pelagic species also found off Sicily
Bigeye threshers live mostly in the open sea and also make use of great depths. Occasionally, however, they approach the coast. According to Tiralongo, the species is regularly recorded mainly in southeastern Sicily and can even occur there more frequently than the common thresher (Alopias vulpinus).
For bathers, the catch does not constitute a specific warning signal. Tiralongo explained that no attacks by this species are known from the Mediterranean. Bigeye threshers hunt fish and cephalopods; humans are not part of their prey spectrum.
Bycatch kills a threatened species
The species is particularly susceptible to fishing pressure. In the global IUCN Red List, the bigeye thresher is classified as Vulnerable, and as Endangered in the regional assessment for the Mediterranean. Like other large sharks, it grows relatively slowly and produces only a few offspring. Losses due to bycatch can therefore burden populations for a long time.
The protective framework is clear: The EU regulation applicable for 2026 prohibits the targeted fishing of thresher sharks of the genus Alopias. For the bigeye thresher, neither parts nor whole carcasses may be kept on board, transshipped, or landed. However, the report does not indicate what happened to the carcass after the video recordings or whether authorities investigated the incident.
