Production of Live Offspring from Unilateral (Left) Ovariectomized Potamotrygon Rays (Potamotrygon castexi, P. leopoldi, P. motoro)
Abstract
Left ovariectomies have been performed to sterilize select female batoid species.1 Consequently, between 2018 and 2019 multiple Potamotrygon rays (n=1 P. castexi; n=1 P. leopoldi; n=6 P. motoro) underwent left ovariectomies to investigate this technique for reproductive management of a mixed gender population. At time of surgery, individuals ranged in age from juvenile to adult. Rays were anesthetized with MS222 buffered with sodium bicarbonate and a left cradiodorsal surgical approach was made to isolate and excise the left ovary. All rays tolerated the procedure and had uneventful recoveries. After a post-operative period, females were cleared for cohabitation with males. At curatorial discretion up to eight females and six males were combined in a mixed species freshwater touch pool of Potamotrygon rays and teleost species. In December 2020, three live and one premature autolyzed pup were noted in the habitat. The following day the adult females were examined via ultrasound and separated from the males. Four dams were identified which produced eight viable offspring and four premature abortions over subsequent days. A large right ovary was observed in all the females with no evidence of left ovarian tissue present. Although previous studies have found the left ovary to be more functionally active than the right based on folliculogenesis in Potamotrygon species, the females in this study demonstrate that the right ovary alone can produce live offspring.2,3 Furthermore, the enlarged right ovary observed in these females suggests that removal of the left ovary may result in compensatory hypertrophy of the right ovary.
*Presenting author
Literature Cited
1. George, RH, Gangler R, Steeil J, Baine K. 2014. Ovariectomy of sub-adult southern rays (Dasyatis americana) as a tool for managing an exhibit population. Drum and Croaker 45:19–23.
2. del Mar Pedreros-Sierra T, Arrieta-Prieto DM, Mejía-Falla PA. 2016. Reproductive system of females of the Magdalena river endemic stingray Potamotrygon magdalenae: anatomical and functional aspects. J Morphol 277(5):680–697.
3. da Silva MI, et al. 2017. Morphology and morphometry of the ovaries and uteri of the Amazonian freshwater stingrays (Potamotrygonidae: Elasmobranchii). Anat Rec 300:265–276.