Fishery-biological and ecological characteristics of the Axillary seabream, Pagellus acarne (Risso, 1827) in the eastern Adriatic sea

Istraživanje je obavljeno na 1188 jedinki batoglavca Pagellus acarne (Risso, 1827) koje su ulovljene na području istočnog Jadrana. Raspon ukupnih dužina tijela analiziranih jedinki bio je u rasponu od 5,5 do 29,5 cm (16,9 ± 4,1 cm), a mase od 1,0 do 397,4 g (69,39 ± 45,71 g). Omjer mužjaka i ženki bio je 1:1,28, a značajna razlika je utvrđena između srednjih dužina mužjaka (18,7 cm) i ženki (20,2 cm). Dužinsko maseni rast batoglavca bio je pozitivno alometrijski (b=3,282), a vrijednost indeksa kondicije je bila 1,168. Statistički značajne razlike u morfometrijskim odnosima između mužjaka i ženki nisu utvrđene. Intenzitet hranjenja batoglavca bio je najveći u proljetnom, a najmanji u zimskom razdoblju. Batoglavac se uglavnom hrani pridnenim beskralježnjacima, a neohodni plijen su rakovi i mnogočetinaši. Starost batoglavca određena je izravnim očitavanjem otolita; najstariji mužjak imao je 6 godina, a najstarija ženka 11. Rast batoglavca opisan je von Bertalanffyevim modelom (L∞ = 27,0 cm; K = 0,29; t0 = -1,52; R2 = 0,902). Ovu vrsta je protoandrični dvospolac, a razdoblje mrijesta je od kolovoza do prosinca. Fekunditet ženki je nizak. Vrijednost koeficijenta ukupne smrtnosti (Z=0,76) posljedica je prirodne (M=0,34) i ribolovne smrtnosti (F=0,42). Razina iskorištavanja batoglavca je E=0,55.The study was conducted on 1188 individuals of axillary seabream Pagellus acarne (Risso, 1827) caught in the eastern Adriatic. Total body lengths of the analyzed specimens ranged from 5.5 to 29.5 cm (16.9 ± 4.1 cm), and weighed from 1.0 to 397.4 g (69.39 ± 45.71 g ). Male to female ratio was 1:1.28, and a significant difference was found between the mean length of males (18.7 cm) and females (20.2 cm). Length-weight relationship of P. acarne was positively allometric (b = 3.282), and the estimated condition factor was 1.168. Statistically significant differences in the morphometric relationships between males and females were not observed. Feeding activity was highest in spring and lowest in winter. Axillary seabream feeds mainly on benthic invertebrates and its prey constitutes mainly of crustaceans and polychaetes. Age was determined by direct reading of otoliths; the oldest male was 6 years old, and the oldest female 11 years old. Growth of axillary seabream was described with von Bertalanffy model (L ∞ = 27.0 cm, K = 0.29, t0 = -1.52, R2 = 0.902). This species is characterized by protandric hermaphroditism and its spawning period lasts from August to December. Females are characterized by relatively low fecundity. The value of the coefficient of total mortality (Z = 0.76) is a consequence of natural (M = 0.34) and fishing mortality (F = 0.42). The exploitation ratio was E = 0.55