Distribution of batoid demersal assemblages on the continental shelf of the Gulf of Tehuantepec

Abstract

Information on the relationship between batoid demersal assemblages and environmental factors is scarce. We captured a total of 23414 batoids belonging to 16 species with bottom trawls at 243 sampling stations in the Gulf of Tehuantepec, Mexico. The species Urotrygon rogersi, Urotrygon chilensis and Narcine vermiculatus represented 70.1% of the abundance and 46.3% of the biomass. Five batoid assemblages were identified using hierarchical cluster and similarity profile analyses. Four assemblages were located at depths less than 40m and one assemblage was located at depths between 40 and 62m. The main batoid group was located in front of the most important lagoon complexes. The abundance biomass comparison method indicated that small species were dominant in terms of abundance in most assemblages. The set of environmental conditions and habitat characteristics (longitude, depth and sea surface temperature) present in the Gulf of Tehuantepec predicted important changes in the batoid community and affected its spatiotemporal distribution pattern.

Presence of pregnant females of the Gorgona guitarfish, Pseudobatos prahli, in the Mexican tropical Pacific

“…(2014) reported the presence of P. prahli ; nonetheless, those records corresponded to specimens described in the present study. Second, the presence of this species has not been reported in studies of the demersal ichthyofauna caught using trawl nets on the continental platform (5–62 m depth) (Acal & Arias, 1990; Núñez‐Orozco et al ., 2013; Tapia‐García & García‐Abad, 1998; Torres‐Huerta, López‐Pérez, et al ., 2019). Third, the photographic records of the diver collaborators in Huatulco indicate the presence of the species during the Tehuanos .…”

Spatial pattern of distribution and reproductive strategy of vermiculate electric‐raysNarcine vermiculatus

“…By‐catch of these organisms is estimated to affect more than 100 species of elasmobranchs classified on the Red List of the IUCN as threatened species (Polidoro et al ., 2008; Žydelis et al ., 2009). Concerns are increasing about the human perturbation (fishing pressure) in the demersal communities, especially those located in the Gulf of Tehuantepec (Tapia‐García, 1998; Torres‐Huerta et al ., 2019).…”

“…These three species contribute to c . 70.1% of the capture of batoids in the region (Tapia‐García & García‐Abad, 1998; Torres‐Huerta et al ., 2019). It is not of economic importance in the region because its size does not exceed 30 cm L T ; therefore, it is part of the discarded fauna (Tapia‐García & García‐Abad, 1998).…”

“…Furthermore, in the Gulf of Tehuantepec N. vermiculatus is one of the most abundant demersal batoids in the by-catch of trawling in the shrimp demersal fishery, along with thorny stingray Urotrygon rogersi (Jordan & Starks 1895) and the blotched stingray Urotrygon chilensis (Günther 1872). These three species contribute to c. 70.1% of the capture of batoids in the region (Tapia-García & García-Abad, 1998;Torres-Huerta et al, 2019). It is not of economic importance in the region because its size does not exceed 30 cm L T ; therefore, it is part of the discarded fauna (Tapia-García & García-Abad, 1998).…”

“…Spatial structureVermiculate electric-ray N. vermiculatus is considered one of the three most abundant species of demersal batoid in by-catch with trawl nets in the Gulf of Tehuantepec, contributing c. 18.6% of the batoid catch(Tapia-García & García-Abad, 1998;Torres-Huerta et al, 2019). This batoid showed an irregular spatial structure in the Gulf of Tehuantepec.…”