Length–weight relationships of eleven demersal ray and shark species (Elasmobranchii) from the southern Gulf of Mexico

The length–weight relationships (LWR) of eleven demersal elasmobranch species captured in the southern Gulf of Mexico were estimated and assessed to provide previously absent somatometric conversion factors. A total of 8852 specimens representing eight families and eleven species caught as bycatch in the Mexican shrimp trawl fishery were analyzed. The following species were covered: Hypanus americanus (Hildebrand et Schroeder, 1928); Gymnura lessae Yokota et Carvalho, 2017; Narcine bancroftii (Griffith et Smith, 1834); Dipturus olseni (Bigelow et Schroeder, 1951); Rostroraja texana (Chandler, 1921); Pseudobatos lentiginosus (Garman, 1880); Rhinoptera bonasus (Mitchill, 1815); Sphyrna tiburo (Linnaeus, 1758); Squatina dumeril Lesueur, 1818; Mustelus canis (Mitchill, 1815); Mustelus norrisi Springer, 1939. The values of the allometric growth parameter b ranged from 2.5 to 3.2, consistent with the expected range. The somatometric growth exhibited negative allometry in fifteen estimations, isometry in six, and positive allometry in two. The LWR differed by sex in five of the six species examined under this criterion, with females consistently exhibiting greater size and weight than males. This study provides the first published LWR for Narcine bancroftii , Dipturus olseni , Rostroraja texana , and Pseudobatos lentiginosus , along with novel LWR estimates for Hypanus americanus , Gymnura lessae , Rhinoptera bonasus , Squatina dumeril , and Mustelus canis in the Gulf of Mexico. It also presents new maximum lengths for R. texana and P. lentiginosus .