Diet and feeding strategy of smooth butterfly rayGymnura micrurain northeastern Brazil

Abstract

Summary The purpose of the present study was to analyze the diet of the smooth butterfly ray Gymnura micrura using qualitative and quantitative approaches to describe the feeding spectrum as well as ecological aspects related to feeding and niche width. The rays were obtained through monthly sampling as by‐catch from bottom trawl fisheries in northeastern Brazil from August 2007 to July 2008. A total of 286 stomachs were sampled, of which 176 contained food items. G. micrura is a predator in the region that feeds intermittently on large whole prey items, followed by a long period of digestion with simply little or no feeding activity. A low diversity of food items was found in the G. micrura diet, with an absolute predominance of teleosts, especially the roughneck grunt Pomadasys corvinaeformis. It is suggested that the species has a narrow feeding niche and a high degree of specialization. This presumed high degree of feeding specialization is discussed and the findings are compared in light of similar studies for closely related species, allowing to propose the family as primarily constituting piscivorous rays.

Comparative diets of sympatric batoid elasmobranchs in the Gulf of Oman

“…The stomach contents of G. poecilura in cluded mostly teleosts, similar to other Gymnura spp. (Jacobsen et al 2009, Yokota et al 2013, Barría et al 2015, Yemiş ken et al 2018. Teleosts were also the most common prey in the diet of Torpedo sinuspersici, consistent with previous studies conducted on other Torpedo species conducted in other areas (Bray & Hixon 1978, Barría et al 2015, Espinoza et al 2015.…”

“…The stomachs of some marine predators, like elasmobranchs, are often found to be empty or contain highly digested prey remains that are difficult to identify (e.g. Jacobsen et al 2009, Yokota et al 2013). …”

Discerning the dietary habits of the smooth butterfly ray Gymnura lessae using two distinct methods, otolith identification and metagenetics

“…The species that is now described as G. lessae is a common coastal ray ranging from the northern Caribbean Sea to the northeast Atlantic Ocean (Yokota & de Carvalho, ). Diet studies of other Gymnurids have found these species to be teleost‐specialised feeders that feed intermittently on relatively large prey (Jacobsen et al ., ; Yokota et al ., ). Therefore, quantifying the diets of Gymnurids can be difficult because of high frequencies of empty stomachs and extended periods of digestion resulting in poor prey identification (Bizzarro, ; Jacobsen et al ., ; Yokota et al ., ).…”

“…Diet studies of other Gymnurids have found these species to be teleost‐specialised feeders that feed intermittently on relatively large prey (Jacobsen et al ., ; Yokota et al ., ). Therefore, quantifying the diets of Gymnurids can be difficult because of high frequencies of empty stomachs and extended periods of digestion resulting in poor prey identification (Bizzarro, ; Jacobsen et al ., ; Yokota et al ., ). In addition, the only G. micrura diet study was conducted in north‐eastern Brazil and thus does not portray the dietary habits of the North American G. lessae (Yokota et al ., ).…”

“…Therefore, quantifying the diets of Gymnurids can be difficult because of high frequencies of empty stomachs and extended periods of digestion resulting in poor prey identification (Bizzarro, ; Jacobsen et al ., ; Yokota et al ., ). In addition, the only G. micrura diet study was conducted in north‐eastern Brazil and thus does not portray the dietary habits of the North American G. lessae (Yokota et al ., ). Given the lack of dietary information for G. lessae , a species with implications for fisheries management due to potentially being a high trophic level predator, the aim of this study was to examine the diet of the species in a northern Gulf of Mexico estuary using a combination of free‐otolith identification and genetic techniques.…”