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Morphology, morphometries and compounds of sulcus acusticus of sagittal otoliths of two gurnard species ( Aspitrigla cuculus and Eutrigla gurnardus ) from north-central Adriatic Sea (north-eastern Mediterranean) were investigated. The study objectives were to find morphometric variables and shape variability of sulcus acusticus of these two closely related sound producers species linked to developmental changes from juvenile to adult stage and species-specific pattern which influenced ecomorphological adaptations of the auditory system. The method used was a combination of multivariate techniques, X-ray diffractions pattern and ultrastructural investigation by SEM. Multivariate analysis (PCA, LDA and PERMANOVA) performed on standardized morphometrics of a total of 202 individuals, significantly separated four groups: A. cuculus juveniles, A. cuculus adults, E. gurnardus juveniles and E. gurnardus adults due to different life history characteristics. At intra-specific levels higher mean values of sulcus area/otoltih area (S:O) ratio of adults than the juveniles were observed within A. cuculus and not for E. gurnardus . At inter-specific levels significant differences were seen between adults and not between juvenile groups. Considering all the groups, the main variability on sulcus area were observed for caudal part of the sensorial macula. Although no differences in compounds were shown by X-ray diffraction at intra-specific level, the crystals on sulcus acusticus were different in shape, size and arrangement between juveniles and adults of each gurnard. The crystals of juveniles were quite enmeshed into otolith matrix and showed a rod/smooth-shape. The crystalline arrangement of adults became more complex with larger, rod/rectangular-shape and well-formed faces. Ontogenetic and specie-specific differences might be related to specie-specific physiological factor (i.e sexual maturity), depth distribution and feeding patterns that change during gurnards growth. These changes, relating to both endogenous and exogenous factors, were marked by the sulcus acusticus which provided a useful tool for fish ontogenetic, physiological and ecological studies. [ABSTRACT FROM AUTHOR]

Background. Red gurnard, Chelidonichthys cuculus (Linnaeus, 1758), is distributed in the Mediterranean Sea, Black Sea, and in the eastern Atlantic Ocean from Norway to Mauritania, although it is rarely found in the North Sea and on the Norwegian shelf. The aim of this work was to conduct a comprehensive study of red gurnard in the Adriatic Sea on selected aspects the population biology and some of its environmental implications. Materials and methods. The sampling covered the entire subdivision GSA17 (north-central Adriatic Sea) and it was based on several bottom trawl surveys of MEDITS and GRUND projects from 2000 through 2009. Biometric parameters, as well as the spatial- and depth distributions were analyzed. The parameters such as the length-weight relation, sex, gonad maturity stage, and the stomach content were determined on a subsample of 539 specimens collected seasonally (summer and autumn-winter) within 2007-2009. The data were processed statistically. Results. Chelidonichthys cuculus was mainly distributed in the central Adriatic. Juveniles showed a distribution in shallower waters while adults tended to migrate towards the Croatian coast at greater depths. The total length of the fish sampled ranged from 40 to 303 mm (TL). We assumed the length of 100 mm as a threshold separating juveniles from adults and the length range of 170-190 mm as the maturity size for females and males. Isometric- and allometric growth patterns were showed for the juveniles and the adults, respectively. The diet was based almost exclusively on crustaceans (IRI% > 98%) and it did not change upon reaching the sexual maturity. Chelidonichthys cuculus should be considered a specialist predator feeding mostly on necto-benthic lophogastrids (IRI% > 72%). Conclusion. This work constitutes an attempt to summarize some environmental and biology aspects of the red gurnard in Adriatic population: differences in depth distribution and growth were found between juveniles and adults but not in diet. Males and females showed differences in growth parameters. 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. [ABSTRACT FROM AUTHOR]

The article presents a study focusing on the estimation of the size at first maturity of triglid fishes in the Adriatic Sea, northeastern Mediterranean. As stated, 1602 specimens of the fish were caught and analysed for the study. It states that sex and maturity stages of these fishes were determined by macroscopic examination. The findings of the study show that males attain sexual maturity at smaller sizes than females.

Length–weight relationships were estimated for the first time for seven species of gurnards (Triglidae) based on data collected over the past 27 years in the Adriatic Sea (northeast Mediterranean). Results show significantly different relationships between juveniles and adults (females and males combined) for Aspitrigla cuculus, Eutrigla gurnardus, Chelidonichthys lucerna and Lepidotrigla cavillone. Isometric growth of juveniles is indicated for four species, allometric growth of adults for all species. [ABSTRACT FROM AUTHOR]

A total of 1,114 tub gurnard (Chelidonichthys lucerna L., 1758) were caught by trawl surveys carried out between May 2005 and March 2007 in the Adriatic Sea (north eastern Mediterranean). Females ranged from 113 to 415 mm TL and males from 128 to 299 mm TL. At 50% maturity, females matured at a fork length of 270 ram, while males matured at 220 mm. The tub gurnards prey mainly crustaceans and fishes. Molluscs are also consumed. A length around 180 mm is a critical size that coincides with the slope to great depths, the migration along the Italian coast towards the Croatian coast, the start of sexual maturity and the change of their main food, from crustaceans to fish. [ABSTRACT FROM AUTHOR]