First Records with Biological Notes of Umbrina ronchus, Valenciennes, 1843 (Osteichthyes, Sciaenidae) in the Strait of Sicily (Central Mediterranean Sea)

Between September and October 2021, a total of seven adult specimens (five females and two males) of Umbrina ronchus Valenciennes, 1843 were caught in the waters off Portopalo di Capo Passero and Porto Empedocle (the south-eastern coast of Sicily). This was the first record of this species in the Strait of Sicily and the deepest record of this species within the Mediterranean Sea. Individuals of U. ronchus ranged from 180-240 mm total length and 69-149 g total weight. Gonad stages ranged from maturing to spent/resting. Otoliths sagittae were oval shaped with high rectangular yet complex contour. Counting the growth zones by transverse section, the estimated age ranged from 3 to 5 years. Since sciaenids are considered a high-longevity species, a quite recent settlement of U. ronchus in the Strait of Sicily is suggested. As the biogeographic nature of the Strait of Sicily is the main boundary between the western basin, which is characterized by a high affinity for (sub)tropical Atlantic species such as U. ronchus, and the eastern basin, which has an affinity for the indo-pacific warm waters species, the present records could be the limit to the eastward expansion of the geographic distribution of U. ronchus in the Mediterranean Sea.

Automated summary

Between September and October 2021, seven adult specimens of Umbrina ronchus were discovered in the Strait of Sicily, marking the first record of the species in this area. These specimens also represent the deepest record of U. ronchus in the Mediterranean Sea. The individuals ranged in size and weight, and their reproductive stages and otolith shapes were analyzed to estimate their age. The presence of U. ronchus in the Strait of Sicily may indicate a limit to its eastward expansion within the Mediterranean Sea, due to the biogeographic nature of the strait.