Morphologic and morphometric analysis of the otoliths: sagitta, asteriscus and lapillus of istiophorus platypterus (perciformes: istiophoridae) in the mexican pacificcoast

In the present study morphologic and morphometric analysis is carried out for the first time in the three pairs of otoliths of the sailfish Istiophorus platypterus (Shaw 1792): sagittae, asterisci and lapilli. Samples were obtained during a period that covers the years from 2001 to 2003, in 11 fishing tournaments in different ports of the Central Mexican Pacific, and in 6 fishing cruises of median size ships. Sagittae of I. platypterus, as those from other billfishes, is characterized by presenting an excisura majorthat divides the otolith in rostrum and posrostrum, and an excisura minor that divides the otolith in posrostrum and pararostrum, being this a peculiar character observed in these species and in the dolphinfish. The growth of these three pairs of otoliths is eccentric to the core; a larger quantity of material is deposited in the dorsal areas and borders, in relation to the ventral areas. No statistically significant morphometric differences were observed between the right and left otolith and between sexes. Seasonal growth rings could notbe observed in the sagittae, but were present in a someasterisci. Results are discussed with those reported by other authors. It is recommended that studies of daily growth increases in one-year organisms or less be carried out. We suggest that a capture quota of this fishery is given to the commercial fisherman.