Background: An estimated one third of elasmobranchs are considered threatened, facing pressures including overfishing, habitat destruction, and climate change. The endangered Maugean skate (Zearaja maugeana) is one such elasmobranch and is the focus of this research. The use of assisted reproduction technologies has several advantages over natural mating, including management of genetic diversity, avoiding the need for hormonal synchronisation, and circumventing the transport and housing of males for insemination.
Methods: Given the small population size of the Maugean skate, techniques are being developed and proof of concept determined in proxy species prior to applying promising protocols to the Maugean skate specifically. Semen and blood are collected once monthly for a year to assess for seasonal differences in semen quality and health parameters, and serial semen evaluation is performed to assess longevity. Sperm morphology is assessed. Semen extenders and cryoprotectants utilised in other elasmobranch species are being evaluated for their impact on motility and viability of Maugean skate semen and modified as needed. Reproductive endocrinology and anatomy of captive female Maugean skates will be examined to determine optimal timing and method of artificial insemination.
Results: Sperm morphology of the Maugean skate is consistent with that of other elasmobranchs. Motility and viability of raw, chilled semen is retained for several days, with longevity improved with the addition of semen extenders. A baseline cryopreservation protocol has been developed with promising post-thaw results.
Conclusion: The unpredictability of environmental conditions in Macquarie Harbour, the exclusive habitat of the endangered Maugean skate, suggests that expanding upon ex situ reproductive programs is necessary for the recovery of the population. The threat of habitat loss and population decline faces most – if not all - elasmobranch species as a whole and therefore the results of this research could be extrapolated to ex situ conservation programs worldwide.