Growth and reproduction of Echeneis naucrates from the eastern Gulf of Mexico

This study describes growth and reproductive characteristics of a facultative elasmobranch symbiont, Echeneis naucrates. Females grew slower but achieved a larger size than males (growth coefficient, K = 0.25 and 0.38 year⁻¹, and mean maximum size, L_∞= 603 and 477 mm, respectively). Mean relative batch fecundity was 39.5 (s.d. = 13.1). Gonadosomatic indices peaked in July and August for males and females, respectively, with histology evidence of readiness to spawn or active spawning in August. Host‐symbiont length ratios increased linearly with sharksucker length (y = 0.0402 + 0.0003x, adjusted R² = 0.56).