Age, growth, and diet of axillary seabream, Pagellus acarne (Actinopterygii: Perciformes: Sparidae), in the central Aegean Sea
Acta Ichthyologica et Piscatoria
İlhan D. 2018. Age, growth, and diet of axillary seabream, Pagellus acarne (Actinopterygii: Perciformes: Sparidae), in the central Aegean Sea. Acta Ichthyol. Piscat. 48 (4): 329-339. Background. The knowledge of the age, growth, and feeding ecology of fish species is essential for conservation, monitoring, and management activities required for the sustainable use of fish stocks. The objective of this work was to describe the growth and feeding of Pagellus acarne from the Gulf of İzmir, central
... Aegean Sea. The information provided in this study contributes to the knowledge which is for sustainable management applications. Material and methods. The study was carried out to investigate the growth and feeding characteristics of axillary seabream, Pagellus acarne (Risso, 1827), in the Gulf of İzmir, the central Aegean Sea, from commercial trawl fishery between October 2012 and September 2013. Age and growth were determined by annuli counts of sagittal otoliths. Length-weight relation and the von Bertalanffy equation were used to evaluate the fish growth. Percentages by number, weight, and frequency of each food category were determined, and the index of relative importance (%IRI) was calculated to define the main food categories. A similarity of diet was also examined according to a season and fish size. Results. A total of 2036 specimens' were analysed. The lengths ranged from 7.5 to 22.0 cm and the weights ranged from 4.55 to 138.45 g. For the age determination, a total of 547 left sagittal otoliths were extracted. The age ranged from 0 to 4 years. Von Bertalanffy growth parameters were determined from mean lengths of age groups and the following parameters were obtained: L ∞ = 27.75 cm, 22.45 cm, and 25.61 cm; k = 0.201 year -1 , 0.341 year -1 , and 0.249 year -1 ; t 0 = -2.347 years, -1.554 years, and -1.938 years; φ´ = 2.190, 2.235, and 2.213 for females, males, and both sexes combined, respectively. Stomach content analyses revealed that Pagellus acarne was defined as a carnivorous, euryphagous, and zooplanktivorous species, and Copepoda (Harpacticoida), Polychaeta, and Decapoda were the most important prey groups. Conclusion. This study provides the age, growth, and the first detailed information on the feeding composition of axillary seabream from the central Aegean Sea. Results reported in this work will contribute to management strategies and regulations needed for sustainable conservation for the remaining stocks of the species.