Introduction: The Maugean skate (Zearaja maugeana) is a microendemic and Endangered elasmobranch confined to Macquarie Harbour, Tasmania, the species’ only remaining habitat. Severe population declines and ongoing environmental stressors have raised concerns for its survival, prompting the establishment of an ex-situ conservation program to safeguard the species from extinction. This program provides an unprecedented opportunity to study the reproductive biology of Z. maugeana, complementing limited knowledge from field observations.
Methods: In December 2023, two Maugean skate adults (one male and one female) were brought into captivity to initiate a long-term “insurance population”. Reproductive activity in the adults has been documented, including mating patterns, egg-laying frequency and reproductive timing. Genetic parentage analysis was performed on 85 hatchlings to assess paternity and determine whether fertilisation involved sperm stored prior to capture or sperm from the captive male.
Results: Since entering captivity, the adult female has laid 358 eggs, resulting in 135 hatchlings, averaging two eggs every 4.2 days. Although a mating event was observed in August 2024, genetic analysis revealed no contribution of the captive male. Instead, five distinct fathers were detected, with one dominant sire accounting for 76% of hatchlings. These results confirm fertilisation from long-term stored sperm acquired in the wild and provides the first evidence of sperm storage and selective sperm use in Z. maugeana.
Discussion: These findings reveal complex mechanisms of sperm storage, sperm selection and sustained reproductive activity, offering key parameters for ground truthing field data and refining population models. Our results highlight the important opportunity provided by ex situ research to uncover reproductive mechanisms in a data-deficient, range restricted elasmobranch, directly informing conservation breeding strategies and the long-term recovery of this endangered species.