Resumen del producto

Blue marlin, Makaira nigricans, is the second most important recreational fishery species for the southern tip of the Baja California peninsula, Mexico. Despite its economic value, little is known about blue marlin age and growth. To study age and growth, we sampled 184 blue marlin landed by the sport fishing fleet at Cabo San Lucas, Baja California Sur, México, between January 2005 and December 2006. All sampled individuals were female. From each fish we recorded postorbital length and sectioned the fourth spine from the dorsal fin to estimation of age and growth rates. Samples ranged in length from 114 to 321 cm, with those of 170 to 210 cm predominating (65% of individuals sampled). The strong positive relationship between the diameter of the fourth spine from the dorsal fin (DS) and the postorbital fish length (R2=0.84) suggest that this structure is reliable for being use in estimations of age and growth rates of blue marlin. We found that the appropriate place to obtain a thin section of the spine (thickness of 0.45 mm) is near the base. We counted the opaque-hyaline bands in each spine section and assumed that an opaque band followed by a hyaline band is an annual mark. Our results show that sport fishermen are catching seven age groups (1, 2, 3, 4, 5, 6 and 8 years old), with the age-groups 2 and 3 being the most abundant. Interestingly, we found no representatives of age groups 0 or 7. The estimated parameters that represent the individual growth for female blue marlin according to von Bertalanffy’s equation (k=0.38, t0=-0.16, and L?=299.66 cm) suggests that they have very fast growth in the early years of life, reaching 56 and 70% of their asymptotic length at age 2 and 3 respectively.

Palabras clave: Striped marlin; Growth; dorsal-fin spines

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