First record of ovigerous Callinectes sapidus (Rathbun, 1896) in the Gargano Lagoons (south-west Adriatic Sea)

The blue crab Callinectes sapidus (Rathbun, 1896), a native to western Atlantic coasts, is widely recorded in various Mediterranean regions, including the Gargano lagoons in the Adriatic Sea. This study investigated selected biological traits of Callinectes sapidus females in the Lesina and Varano lagoons during their breeding migration to more saline waters. In total, 19 individuals of Callinectes sapidus, 15 females and four males, were collected in the lagoons near the mouths of the seaward channels. The specimens' Carapace Width ranged from 115 to 230 mm, classifying them as medium to large crabs. In Varano lagoon in April and May 2014, two ovigerous females with egg masses of 63.39 g and 11.65 g respectively were captured. This represents the first record of ovigerous females of C. sapidus in this lagoon. The average Gonado-Somatic Index was 2.91±1.82 and 1.65 ± 0.65 for the specimens captured in Varano and Lesina lagoons, respectively. The average Hepato-Somatic Index was 3.88±0.80 and 4.22±0.31 for specimens captured in Varano and Lesina, respectively. Egg diameter ranged between 0.23 and 0.35 mm. Histological analysis of gonads showed stages from III to V, with individuals in emission or postissuance stages. This study presents evidence of the establishment of C. sapidus populations in Varano lagoon in the south-west Adriatic Sea and provides additional information on this species in the Lesina and Varano lagoons.