Captive biology of the pelagic stingray, Dasyatis violacea (Bonaparte, 1832)

Abstract

Pelagic stingrays, Dasyatis violacea, were collected in southern California in summer–autumn 1994–97. The smallest, 40–45 cm disc width (DW) and 2 kg, were estimated to approach age two. In captive growth and feeding experiments from March 1995 to August 2000, the largest male reached 68 cm DW and 12 kg at estimated age 7 years, and the largest female reached 96 cm DW and 49 kg at estimated age 9 years. The growth data could be fitted with both Gompertz and von Bertalanffy growth functions, but the former produced more reasonable values for size at birth, maximum size, and longevity. Consumption of squid was 6–7% of body mass (BM) per day for juveniles 2 years old and decreased to 1.25% BM day^–1 for adults. Food intake for adults was seasonal, with 2 cycles per year with a maximum of ~2.0% and a minimum of 1.0–0.5% BM day^–1 from July to October 1998. The data for gross conversion efficiency (K₁, based on energy values), collected at 20°C with daily feeding to satiation, could be fitted with a linear regression in the estimated mean age range of 3–6 years (K₁ = 0.37 – 0.055 Age).