The dugong, often referred to as a “sea cow,” is a gentle marine mammal. These herbivores are the only living representatives of the family Dugongidae and are closely related to manatees, though they are strictly marine and possess a dolphin-like fluked tail. They inhabit warm coastal waters across the Indo-Pacific, from East Africa to Vanuatu, primarily grazing on vast seagrass meadows. Understanding their longevity and influencing factors is important for their protection.
Dugong Lifespan Revealed
Dugongs live for many decades in the wild. They live between 50 to 70 years, with the oldest recorded reaching 73 years, making them one of the longest-living marine mammals.
Despite their long lives, dugongs have a slow reproductive rate. Females give birth to a single calf every three to seven years, reaching breeding age between six and seventeen years old. This slow breeding cycle means populations recover gradually from declines.
Unlocking Age Secrets
Scientists determine a dugong’s age through methods similar to those used for trees, by examining growth layers in their hard tissues. The primary method involves analyzing the growth rings found in their tusks, which are modified incisors. These rings form annually, providing a reliable record of the animal’s age.
Another method involves studying the layers in their ear bones, known as otoliths. Counting these concentric rings allows researchers to estimate an individual’s age. While these methods provide insights, challenges exist in their application and interpretation, as environmental conditions can influence ring formation.
Influences on Longevity
A dugong’s lifespan is influenced by natural and human factors. Natural elements include the quality of their habitat, particularly the availability of healthy seagrass beds, which are their sole food source. Disease can also impact their health, with infections and parasitic diseases contributing to dugong deaths. While adult dugongs have few natural predators due to their large size, young calves can be vulnerable to sharks, crocodiles, and killer whales.
Human activities pose the greatest threats to their longevity. Entanglement in fishing gear, especially gillnets, leads to accidental drownings as dugongs are air-breathing mammals. Boat strikes are a major concern, as these slow-moving animals often float near the surface, making them vulnerable to collisions. Habitat degradation from coastal development, dredging, land reclamation, and pollution impacts seagrass meadows, reducing their food supply and living space.
Protecting Their Future
Dugongs are currently listed as vulnerable to extinction on the IUCN Red List. Their slow reproductive rate and long lifespan make them particularly susceptible to population declines. To safeguard their future, conservation efforts are underway globally.
These efforts include establishing marine protected areas to conserve seagrass habitats. Legislation protects dugongs in many countries, prohibiting hunting and trade of their parts. Public awareness campaigns aim to reduce human impacts, while research initiatives provide data for effective management strategies. These combined actions ensure the long-term survival of dugongs and the health of their marine ecosystems.