Distribution and some biological parameters of the red gurnard Chelidonichthys cuculus (Actinopterygii, Scorpaeniformes, Triglidae) in the north-central Adriatic sea.

Chelidonichthys cuculus (L.) is distributed in the Mediterranean Sea, Black Sea and in the Eastern Atlantic Sea from Norway to Mauritania, although rarely found in the North Sea and on the Norwegian shelf. The aim of this study is to investigate the distribution patterns, length structure and diet of red gurnard from the Adriatic Sea (northeastern Mediterranean), providing a comparative studies in other areas. Samples were collected in the whole GSA17 - north-middle Adriatic Sea from several bottom trawl surveys of MEDITS and GRUND projects between 2000 and 2009. Biometric parameters, spatial and depth distribution were analyzed. From a subsample of 539 specimens collected seasonally (summer and autumn-winter) in the Italian area between 2007 and 2009, the length-weight relationship, the determination of sex and the maturity stages and stomach content analysis were performed. Data were examined statistically distinguishing by size and sex. C. cuculus was mainly distributed in the middle Adriatic. Juveniles showed a distribution in shallower waters while adults tend to migrate towards the Croatian coast at greater depths. The total length of samples ranged from 40 to 303 mm (TL). Size at 100 mm divided juveniles from adults while at size between 170-190 mm females and males mature were showed. Isometric and allometric growth were showed from juveniles and adults respectively. The diet was based almost exclusively on crustaceans (IRI% >98%) and it didn’t modified around size of sexual maturity. C. cuculus should be a specialist predator feed mostly on necto-benthic lophogastrids (IRI% > 72%). This work constitutes a complex attempt to study together some environmental and biology aspects of the Adriatic population: area and bathymetric distribution by size, sex and season, structural population, sexual maturity and feeding preferences. Extending the studied area and collecting data of red gurnard in the main areas of production should help in better understanding the biology and dynamics of this species.