AGE DETERMINATION AND GROWTH OF YELLOWFIN TUNA, THUNNUS ALBACARES BONNATERRE BY VERTEBRAE

(1) The 24th vertebra was selected to represent each individual after several studies. (2) The relationship between the radius of vertebral centrum (Rmm) and size of the fish (Lcm) is nearly linear, aud can be expressed as a rectilinear regression: L=13.3+6.3R or a curve: L=8.81R0.92 (3) The averages of each ring radius (ri) are as follows: r1=4.14mm r2=6.23mm r3=8.51mm r4=11.13mm r5=13.64mm r6=16.10mm r7=17.27mm r8=18.66mm (4) The means of fork length at the time of ring formation are calculated as follows : l1=39.4cm l2=52.6cm l3=67.0cm l4=83.5cm l5=99.3cm l6=114.8cm l7=122.2cm l8=131.0cm (5) By checking the seasonal change of marginal increment on the vertebral centrum it appears that two rings are formed yearly. By this, the means of fork length at respective age is: O age < 52.6cm I age 52.6cm ?? 83.5cm II age 83.5cm ?? 114.8cm III age 114.8cm ?? 131.0cm