Trophic ecology of the Patagonian skate, Bathyraja macloviana, on the Argentine continental shelf

Abstract

The diet, feeding strategy, and dentition of the Patagonian skate, Bathyraja macloviana, on the northern continental shelf of Argentina were studied from specimens collected during research cruises in September and October 2001. Of a total of 81 stomachs examined, only 3.7% were empty. Cumulative prey curves showed that sample sizes were adequate to describe the main prey items of the diet. Quantitative analysis, a graphical method, and trophic niche breadth indicated the species to be a specialized feeder. The most important prey items were polychaetes, followed by gammarid amphipods, isopods, and crabs. Cumaceans, ophiuroids, and hydrozoans were likely incidentally consumed by mature females. Sexual dimorphism in dentition was observed; mature males had longer and sharper tooth cusps than females or immature males. However, there was a high degree of dietary overlap between mature males and mature females, indicating that dental sexual dimorphism in the species is more important in reproductive behaviour than in differential prey consumption.

Feeding ecology and trophic position of a Mediterranean endemic ray: consistency between sexes, maturity stages and seasons

“…The similar diet exhibited by male and female starry rays can be explained with the fact that both sexes showed similar body size (e.g. San Martin et al 2006;Scenna et al 2006;Barbini et al 2010). Sexual differences in diet are described for ray species with marked sexual dimorphism in size and/or feeding apparatus as a mechanism to reduce the intraspecific competition for food between males and females (Feduccia and Slaughter 1974;Wearmouth and Sims 2008).…”

Comparative feeding ecology of four sympatric skate species off central California, USA

“…Adequate sample size has been assumed if the resulting curve approached an asymptote and displayed a reduction in variability (Hurturbia 1973;Cailliet 1977;Ferry and Cailliet 1996). Although widely used (e.g., Gelsleichter et al 1999;Morato et al 2003;Braccini and Perez 2005;Scenna et al 2006), no quantitative criteria have been developed for this method. The use of qualitative and subjective criteria for the evaluation of sample size sufficiency limits the Biol Fish (2007) 80:197-220 199 utility of this technique and precludes definitive results that are comparable between studies.…”

The trophic ecology of two abundant mesopredators in south-east coastal waters of Tasmania, Australia

“…The order in which the stomachs were analysed was randomised 100 times to exclude sampling order bias (MacKinlay and Shearer 1996;Scenna et al 2006). An asymptotic curve is indicative that suYcient samples were collected to represent each species diet (MacKinlay and Shearer 1996;Scenna et al 2006).…”

“…The order in which the stomachs were analysed was randomised 100 times to exclude sampling order bias (MacKinlay and Shearer 1996;Scenna et al 2006). An asymptotic curve is indicative that suYcient samples were collected to represent each species diet (MacKinlay and Shearer 1996;Scenna et al 2006). A curve was considered to reach an asymptote if at least ten previous values of the total number of prey were within 0.5 of the Wnal value (Huveneers et al 2007).…”

“…Elasmobranchs that consume pelagic or mid-water prey such as teleosts are more likely to have empty stomachs because the number of prey within an area is likely to Xuctuate and requires a degree of proWciency to capture (Hobday 1992). In contrast, elasmobranchs that feed on slow-moving benthic invertebrates tend to have a much lower proportion of empty stomachs (Kamura and Hashimoto 2004;Scenna Collins et al 2007;Rinewalt et al 2007;Robinson et al 2007;Yick et al 2011), as these prey can be caught relatively easily and are usually in high abundance; thus, feeding is more likely to be continuous. However, the lower digestion rate of some invertebrates (e.g.…”