![]() The cause of failure in this case was not identified but may have been due to errors in timing of insemination, semen quality, or method of insemination. In 2005, Australian researchers attempted to synchronize AI with ovulation using sonography in Broadnose Sevengill Sharks ( Notorynchus cepedianus), but failed to produce a pregnancy, despite documentation of ovulation ( Daly and Jones, 2017). ![]() A team of Japanese scientists reported successful AI of Cloudy Catsharks ( Scyliorhinus torazame) in 1995 and Whitespotted Bamboo Sharks ( Chiloscyllium plagiosum) in 1998, with fertility successes of ~77% and ~23%, respectively ( Masuda et al., 2003). To date, AI has been attempted in only a handful of elasmobranch species with mixed success. In other wildlife species, AI has been used to overcome similar reproductive challenges, especially for species in peril ( Blanco et al., 2009 Rodger et al., 2009 Howard et al., 2016), and may be an option for reproductive challenges for elasmobranchs in human care ( Daly and Jones, 2017). ![]() While maintaining male-only or female-only collections minimizes risk of mating related injury and allows for population control, this challenges the ability to maintain genetically diverse populations across zoos and aquariums. ![]() The risk of injury often leads to single-sexed populations being maintained in aquaria. For example, copulation in elasmobranchs can be physically detrimental, especially to females (reviewed in Pratt et al., 2005). Many aspects of elasmobranch (sharks and rays) biology make them good candidates for implementation of artificial insemination for their care and management in zoos and aquariums. AI also has implications for improved animal welfare as mating can present risks to one or both sexes ( Ritter et al., 2019). Thus, AI physically decouples the process of mating for species employing internal fertilization, which can offer alternatives when the barrier to reproduction is a lack of or inappropriate mating behavior ( Huang et al., 2002 Zhang et al., 2004). In its simplest form, AI is the process by which semen collected from a male donor is placed in the reproductive tract of a female. For example, artificial insemination (AI) is one of many reproductive technologies used to aid sexual reproduction in domestic and wildlife species ( Malecki et al., 2008 Faigl et al., 2012). When natural reproduction fails, assisted techniques can be employed to overcome barriers. Reproduction of animals in human care sometimes requires more than simple cohabitation of females and males as the physiological and behavioral processes involved can be complex ( Ottinger and Mench, 1989). With further development, artificial insemination represents a powerful tool that could be used for maintaining genetic diversity for animals housed in aquaria and conservation-based breeding programs for elasmobranchs. This study successfully employed artificial insemination to circumvent barriers to natural reproduction in Zebra Sharks. All females produced at least one hatched parthenote. For the two females housed with the male, no sexual offspring resulted. After the second insemination (September 24 th, 2013), 62 yolked eggs resulted in two sexually produced offspring, 18 and 33 days after insemination, and three parthenogenetic offspring > 213 days post-insemination. After the first insemination (December 15 th, 2011), 143 yolked eggs resulted in no sexually produced offspring and four genetically-confirmed, parthenogenetic offspring. Hatching success for eggs laid by all three females was monitored to compare natural and artificial insemination modes. To determine if assisted techniques could be used to rescue sexual reproduction, artificial insemination was performed in a singleton female twice over a three-year period using freshly collected semen. Among a population of three female and one male Zebra Sharks ( Stegostoma tigrinum), production of young failed despite constant male presence with two of the females. Maintaining self-sustaining populations of zoo and aquarium collections can be challenged when natural reproduction fails within mixed-sex populations however, reproductive success can sometimes be restored with the application of reproductive technologies. 4Delaware Biotechnology Institute, Center for Bioinformatics & Computational Biology, University of Delaware, Newark, DE, United States.3Wildlife Genetics, Department of Comparative Medicine, Loyola University Medical School, Maywood, IL, United States.2Research and Conservation, Georgia Aquarium, Atlanta, GA, United States.1Aquarium of the Pacific, Long Beach, CA, United States.Lance Adams 1*, Kady Lyons 2, Elizabeth Larkin 1, Nicole Leier 1, Janet Monday 1, Chris Plante 1, Jean Dubach 3 and Jennifer Wyffels 4 ![]()
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