Gestation and size at parturition for Mobula kuhlii cf. eregoodootenkee

Abstract

Few data are available describing reproduction in the pygmy devilray, Mobula kuhlii cf. eregoodootenkee, or mobulids in general. Using samples collected from bather-protection gillnets deployed off eastern Australia during 2017–18 we provide further comment on their periodicity, gestation and size at parturition. Twelve adult specimens were necropsied: two were males (99.5 and 106.3 cm disc width–DW); five were pre-ovulatory (112.4–122.0 cm DW) non-gravid females with 15–25 oocytes in their functional left ovary; and five were gravid (112.6–121.0 cm DW), each with a single embryo (24.0–42.3 cm DW) but similar numbers and sizes of ovarian follicles as their non-gravid conspecifics. At 43.2 cm DW or 36% of its mother’s DW, the largest embryo was almost full term. Considering previous data describing early pregnancies, reproduction appears seasonal (but not consecutive) and involves protracted mating and a gestation probably >12 mo. The data reiterate a low reproductive output and a need for appropriate conservation strategies.