Gymnura Altavela Research Articles

Historically, gymnurid rays have not done well in a captive environment. This report describes success in maintaining two specimens of the spiny butterfly ray, Gymnura altavela, in captivity. An aggressive husbandry protocol of tube feeding and force feeding maintained energy levels until the rays began to feed on their own. The rays used their pectoral fins to strike at food items, a behavior they may use in the wild to stun and capture prey. The first estimates of growth in captivity for any species of butterfly ray are given. Growth rates for the male averaged 0.063 mm/day (s.d.=0.030) and 10.253 g/day (s.d.=9.689), whereas growth rates for the female butterfly ray averaged 0.303 mm/day (s.d.=0.215) and 22.777 g/day (s.d.=15.2). Estimates of gross conversion efficiency (Kl) were calculated using the caloric values and known food intake. The estimates of Kl averaged 5.4% (s.d.=3.857) and 16.1% (s.d.=7.511) for the male and female, respectively, with a combined average of 10.8% (s.d.=7.95). These are the first estimates of Kl reported for any species of batoid using direct methods (growth rate and food intake). © 1996 Wiley-Liss, Inc.

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