Growth of bluefin tuna (Thunnus thynnus) in the North-eastern Atlantic and Mediterranean based on back-calculation of dorsal fin spine annuli

The growth of bluefin tuna (Thunnus thynnus) in the North-eastern Atlantic and Mediterranean was analysed using the back-calculation of the dorsal fin spine annuli. Spines from a total of 2678 bluefin tuna, collected from 1984 and 1990-2010, were analyzed. The specimens ranged from 45 to 287 cm straight fork length (SFL). Both linear and power regression functions showed a significant relationship between spine radius and SFL, but power function fitted better than linear (SFL = 42.978R0.884, r2 = 0.98), as also was found in previous studies when a wide range of sizes was available. Two back-calculation equations were used to obtain the back-calculated SFL, Fraser-Lee and Body Proportional Hypothesis (BPH), showing similar results. The Von Bertalanffy growth parameters obtained with the selected BPH model were: SFL = 349.5(1 − e−0.086(t+0.814)). Back-calculated lengths and growth parameters showed similarities with those from previous literature.