Age and growth of the Dolphinfish Coryphaena hippurus in the coast of Oaxaca and Chiapas, Mexico

Daily growth increments were analyzed in otoliths of Dolphinfish (Coryphaena hippurus) in the coasts of Oaxaca and Chiapas, on the central Mexican Pacific, from September 2004 to September 2005. Results showed that it is possible to count daily growth rings in the sagittae, mainly on the pararostrum zone. Seasonal growth rings were not detected, that is, longer than daily periodicity. We consider that this method is ideal to identify daily growth rings in young organisms. As specimen age and the amplitude of the growth rings diminish, these rings can be underestimated because they appear to overlap. The Gompertz growth model best described the first growth phase (L₀= 7.02, G= 3.04, g= 2.89), and the von Bertalanffy constants were: L_¥= 231.65 cm, W_¥= 77.926 kg, K= 0.874, t₀= 0.074. The longevity was estimated at 3.44 years. Sexual dimorphism results in differences in the weight-length relationship and the relative condition factor with males (W= 2.154 · 10^-5 · L^2.788, CF_r= 1.04) having higher values than females (W= 4.608 · 10^-5 · L^2.586, CF^r= 0.96), due to the presence of the bony crest in males.