Growth and length-weight relationship of the striped marlin, Tetrapturus audax (Pisces: Istiophoridae), in Cabo San Lucas, Baja California Sur, Mexico

Abstract

 To determine the age, backcalculate the length, and describe the individual growth and length-weight relationship of the striped marlin Tetrapturus audax, the catch of the sport-fishing fleet from Cabo San Lucas, Mexico, was sampled from 1988 to 1993. The length and weight of 1044 fishes were measured, and the fourth spine of the dorsal fin was collected from 399 of them. The mandibular length (ML) ranged from 156 to 263 cm, and the total weight (TW) ranged from 26 to 100 kg. No significant differences were detected (P > 0.05) in the ML-TW relationship either between sexes or between years. The general relationship was TW = 0.00008*ML^(2.523), showing a negative allometric growth (b < 3, P < 0.05). Ten age groups were determined (2 to 11). The relationship between ML and the dorsal fin radius was highly significant (P < 0.001), justifying the use of the dorsal fin for the age determination and to describe the growth of the striped marlin. The von Bertalanffy growth model was fitted appropriately to backcalculated ML-age data (r² = 0.99) and the values of the parameters were: L_∞ = 221 cm, K = 0.23 per year, and t₀ = –1.6. The striped marlin reaches 45% of the asymptotic length in its first year of life; in the second year the growth rate decreases to 10%, and during the next eight years the growth rate is 4% on average. The present study is the first to report on the individual growth of the striped marlin based on age determination in hard structures.