A Review of Adult Stingray Mortalities at the National Aquarium in Baltimore (1997–2008)
A 260,000-gallon artificial saltwater system at the National Aquarium in Baltimore houses stingrays, sharks, teleosts, and sea turtles. The majority of animals are southern stingrays (Dasyatis americana) and cownose rays (Rhinoptera bonasus). Twenty adult stingray mortalities were reported from 1997 to 2008: five southern stingrays, four cownose rays, three spiny butterfly rays (Gymnura altavela), two pelagic stingrays (Pteroplatytrygon [Dasyatis] violacea), two roughtail stingrays (Dasyatis centroura), two spotted eagle rays (Aetobatus narinari), one bluntnose stingray (Dasyatis say), and one banded guitarfish (Zapteryx exasperata). All animals had unknown birth dates and were assigned either estimated birth dates upon arrival into the collection or minimum ages at death. Mean longevities from arrival date to death date in years ± one standard deviation (SD) were 8.2 ± 6.6 years (range 0.3–18.5) for the group and 13.0 ± 6.2 years (range 2.0–18.5) for only the southern and cownose rays. Mean longevities from minimum estimated birth date to death date ± SD were 10.3 ± 7.4 years (range 1.0–23.0) for the group and 15.4 ± 7.4 years (range 2.0–23.0) for only the southern and cownose rays, these values likely being underestimations. Presenting clinical signs included anorexia (38.9%), coelomic distension (16.7%), neurologic signs (16.7%), generalized edema (5.6%), and cloacal prolapse (5.6%). Gross necropsy and histologic analyses showed skin pathology (50.0%), suspicion of sepsis (47.1%), suspicion of disseminated intravascular coagulation (27.8%), reproductive pathology (17.6%), and neoplasia (5.9%). The majority of southern stingray and cownose ray mortalities reflect changes expected in an aging population of animals.