Going, Going… Dugong                

 

Elizabeth A. Burgess, Ph.D.

Post-Doctoral Researcher
John H. Prescott Marine Laboratory
New England Aquarium

 

The dugong (Dugong dugon) is an unusual marine mammal. Closely related to manatees, the dugong is the only surviving member of a highly specialized group of sea cows (order Sirenia, family Dugongidae); one of only a few large vertebrates that feed on seagrasses; and the only herbivorous mammal that is restricted to a marine environment. Dugongs rely on inshore habitats, which places them in close proximity to humans and their associated impacts. Dugongs are listed as vulnerable to extinction throughout their vast Indo-Pacific range (up to 44 countries). Australia is one of the few countries that still have large populations of dugongs, and is considered the dugong’s last stronghold. Yet along the urban east Australian coast, there appears to have been a 95% decline in dugong populations over the past 60 years. These declines have highlighted a need for reliable regional information concerning life history parameters for this species, including reproduction. Cryptic marine mammals such as dugongs are notoriously difficult to study. These difficulties are exacerbated when dugongs occur in relatively large herds, in turbid waters, are highly mobile, and when individual dugongs are indistinguishable by sight alone. As a result, management strategies for dugongs have incorporated biological data principally obtained from the analysis of carcasses from tropical regions, where incidental drownings and indigenous harvests occur more readily. In response to a critical need to obtain reproductive parameters of dugongs along the heavily impacted urban coastline, a mark-recapture study has been conducted in Moreton Bay, Australia. This project uses a distinct hands-on approach to study dugongs, which has allowed for a better understanding of sexual maturity, pregnancy, reproductive seasonality, reproductive strategies and stress responses in a live dugong population. I hope that this talk will provide an introduction to this unique marine species, and will present new insights gained from using novel research approaches.