Title

Growth, Reproduction, and Age At Maturity of Lessa's Butterfly Ray Gymnura lessae In the Northern Gulf of Mexico

Document Type

Article

Publication Date

9-2022

School

Biological, Environmental, and Earth Sciences

Abstract

In the northern Gulf of Mexico, batoids are caught as bycatch in the shrimp trawl fishery and targeted by recreational bowfishers. The vulnerability of these batoid species to overexploitation is primarily dictated by their life history strategies. Lessa’s butterfly ray, Gymnura lessae, is a sexually dimorphic piscivorous batoid ranging from the northern Caribbean Sea to Massachusetts. Species in the family Gymnuridae have small, poorly mineralized centra; as a result, age and growth has only been described in one species, G. altavela. In this study, we examined size at maturity, reproduction, sex-specific growth (using Electronic Length Frequency Analysis), instantaneous natural mortality, and age at maturity of G. lessae in the northern Gulf of Mexico. Overall, 552 G. lessae were sampled from 2016 to 2018, of which 322 were male and 230 were female. Estimated disc width at 50% maturity was 340.0 mm and 461.4 mm for males and females, respectively. Sex-specific von Bertalanffy growth parameter estimates were DW∞ = 427.1 mm, k = 1.34 year−1, and t0 =  −0.35 years for males, and DW∞ = 882.2 mm, k = 0.40 year−1, and t0 =  −0.56 years for females. Instantaneous natural mortality was higher for males (1.48) than females (0.48). Most age-0 males (93.8%, n = 16) and 30.7% of age-0 females (n = 13) appeared to mature fast enough to mate just 1 year after birth. Our results indicate that G. lessae is fast growing, quick maturing, and relatively fecund in the northern Gulf of Mexico and is thus at low risk of overexploitation.

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