Trophic ecology of the blotched stingray, Urotrygon chilensis (Elasmobranchii: Myliobatiformes: Urotrygonidae), in three areas of the Mexican Pacific

Abstract

Background. There is a current global consensus that to achieve a sustainable use of fisheries resources, management of every organism subject to exploitation is required rather than only those targeted directly by the fisheries. Further understanding the feeding habits of the species in the ecosystem as well as the predator-prey relationships and their trophic levels is crucial. Batoids occupy an important ecological niche as benthic predators in estuaries and bays. There is no directed fishery for the blotched stingray, Urotrygon chilensis (Günther, 1872), but it is commonly caught incidentally by trawl and bottom gillnets fisheries subsequently diminishing its population. Recently, artisanal fisheries in Mexico have become focused on batoid species due to the depletion of shark catches, although there are few studies on its biology and ecology. Materials and methods. We analysed the trophic ecology of the blotched stingray in two main areas from the Mexican Central Pacific to understand the species' diet and detect possible differences throughout fishing areas using stomach content analysis. We analysed the overlap in diets between areas and the trophic level at each area. Results. We analysed 423 specimens and found 15 prey groups. Representatives of the two crustacean higher taxa-Cladocera and Peracarida were the most important food items in the north area, while the crustacean family Penaeidae was the most important in the south area, having no significant overlap between areas (Cλ = 0.33). The estimated trophic position for the blotched stingray was 3.51-3.56 in both areas, and according to the Levin's index, the range of the trophic niche breadth for the blotched stingray was 0.059 and 0.039, which indicates that it is a specialist predator. Conclusion. The blotched stingray is a specialist predator that can adapt to different prey depending on which organisms are present in the ecosystem. It is necessary to continue with these types of studies for the other species inhabiting the area, in addition to monitoring fisheries landings, fishing effort, and variations in biotic and abiotic factors in the area over a long period. However, this study outlines an approach for reaching the ultimate goal of sustainable exploitation of marine resources on an ecosystem level.

Riqueza y abundancia de los batoideos de la Isla Espíritu Santo, Golfo de California

“…Dentro de este orden, fue el género Urobatis quien contribuyó con el mayor número de especies, con tres representantes. Estas especies son sumamente importantes en el funcionamiento del ecosistema, ya que desempeñan un rol importante como depredadores bentónicos (Oñate et al, 2017). Sin embargo, las rayas de este género no tienen importancia comercial, por lo cual no son aprovechadas por los pescadores artesanales.…”

Morphological abnormalities in seven American round ray specimens: A review of America's batomorph anomalies

“…Morphological anomalies recorded in this study for the Urobatis maculatus , Urotrygon chilensis , U. microphthalmum and U. rogersi individuals are most likely related to after‐birth injuries rather than genetic and anthropogenic issues, as has been proposed by other authors (Mejía‐Falla et al., 2011; Suresh & Raffi, 2012; Torres‐Huerta et al., 2015). For example, the majority of the American Batomorphi species are considered as mesopredators, connecting the lower trophic level with the higher levels (Bornatowski et al., 2014; Ehemann et al., 2019; González‐González et al., 2021; Navia et al., 2017; Olmo‐Gilabert et al., 2019; Oñate‐González et al., 2017; Restrepo‐Gómez et al., 2020; Rupp & Bornatowski, 2021; Serrano‐Flores et al., 2021), which supports the speculation of predation of the small‐bodied batomorphs found in this study. However, fishermen's causes, such as amputation, could not be ruled out as probable cause either.…”

Advances in the study of the trophic niche of batoids with distribution in Mexican waters

“…The overlap in the Urotrygonidae family's diet is related to similarities in their buccal morphology, such as muscles, jaws, and teeth, as Rosa‐Meza (2010) reported in the northwest Mexican Pacific. Therefore, benthic ecosystems where the batoids of the Urotrygonidae family inhabit could be more resilient to fishing (Oñate‐González et al., 2017).…”