engleski

Biometric characteristics of small Atlantic bluefin tuna (Thunnus thynnus, Linnaeus, 1758) of Mediterranean Sea origin

The aim of this study was to provide a detailed description of the biometry of the juvenile Atlantic bluefin tuna (FL=50-127 cm) of Mediterranean Sea origin. Regarding meristic features, there were 31.47 (SD=2.096) gillrakers found on the first gill arch, 13.41 (SD=0.494) spines in the 1st dorsal, 33.56 (SD=2.124) soft rays in the pectoral fin, 9.86(SD=0.464) dorsal finlets and 8.90 (SD=0.412) ventral finlets on the tail. The results of morphology analyses indicate that, on average, the head length contributes 28.84% (SD=0.745) ; 1st predorsal length contributes 31.86% (SD=0.915) ; preanal length contributes 61.45% (SD=1.632) ; maximum body height contributes 26.90% (SD=1.001) ; 2nd dorsal fin height contributes 11.11% (SD=1.457) ; pectoral fin length contributes 20.09% (SD=1.550) and caudal fin width contributes 28.60% (SD=1.842) of the fork length. Eye diameter comprises 13.14% (SD=1.471), snout length 33.11% (SD=1.332) and postorbital length 53.75% (SD=1.354) of the head length. The significant change of body proportions, as fish grow in length, has been noted and which leads to the conclusion that the juvenile bluefin’s body does not grow isometrically in size. The continuous decrease of the mean condition factors as body length increased, and a length-weight relationship describing negative allometric growth (ln WW(g) = -3.2965 + 2.8546 ln FL(cm)), indicate the elongation of juvenile bluefin’s body shape during their early life, corresponding mostly to the period before the 1st sexual maturity.

bluefin tuna; biometric characteristics; Mediterranean Sea

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