Observations of reproductive behaviors in the Critically Endangered bowmouth guitarfish Rhina ancylostoma

Abstract

Wedgefishes, family Rhinidae, are collectively identified as one of the most threatened groups of chondrichthyan fishes globally by the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species. Within the family Rhinidae, bowmouth guitarfish Rhina ancylostoma have been designated by the IUCN as Critically Endangered since 2018. Bowmouth guitarfish were first introduced to the Association of Zoos and Aquariums (AZA) in 2005 when the Newport Aquarium, Newport, KY, USA, acquired a single female. In 2007, a male bowmouth guitarfish was added into the collection with the goal of establishing an institutional breeding program and to generate foundational knowledge for future breeding programs. This study presents an ethogram of mating behaviors exhibited by a mixed sex group of bowmouth guitarfish using behavioral observations from December 2017 through August 2022. The observed interactions between male and female bowmouth guitarfish led to the identification of 5 male reproductive behaviors: hovering, chasing, wrapping up, flipping/rolling, and copulation. These 5 behaviors were directly linked with successful reproduction, e.g. active breeding and live parturition, in the imperiled species R. ancylostoma. The breeding behavioral knowledge presented within this study provides the first step to a viable breeding program, a critical tool for conserving wild populations.