Marine scientists have discovered that black teatfish sea cucumbers, an endangered species, can live for decades, with some individuals reaching over 100 years, according to a genetic mark-recapture study. The research, conducted by the Australian Institute of Marine Science (AIMS) in partnership with the University of Sydney and Southern Cross University, compared DNA samples from a population collected in a no-take zone of the Great Barrier Reef Marine Park in 2000 with samples collected from the same location 24 years later. A small biopsy was taken from each animal, and the animals were returned to their original location. Modeling was used to estimate their lifespan. The study is published in the journal iScience. Dr. Sven Uthicke, a Senior Principal Research Scientist at AIMS, said the findings suggest black teatfish populations recover much more slowly from fishing pressure than previously assumed. The study found that 60% (33) of the animals sampled in 2024 were the same as those sampled in 2000, indicating extreme longevity and very low natural death rates. The average lifespan of the black teatfish was estimated to be 24 to 27 years, while some individuals lived for more than 100 years. Most of the recaptured animals had grown very little over the 24-year period, and many had become smaller. Black teatfish are a highly valued delicacy in some cultures and are fished in Australia, the Pacific Islands, and Southeast Asia. They are sold for more than AU$400 per kg in Hong Kong but are now seldom seen in Asian markets as wild stocks have been overfished. They can be found throughout the Great Barrier Reef, and their distribution extends to Western Australia. Sea cucumbers play an important role in tropical marine ecosystems, recycling nutrients on the ocean floor and mixing sediment. Recent studies also show that healthy sea cucumber populations can enhance coral health. Black teatfish is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES) and is currently classified as Endangered by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Dr. Uthicke said current fisheries management approaches needed to be reevaluated because they currently assumed tropical sea cucumbers could replace harvested individuals faster than the research results indicated. "Harvesting long-lived reef animals like black teatfish is unlikely to be sustainable under current fishing pressures and environmental stress," he said. Dr. Maria Byrne, a professor of marine biology at the University of Sydney, said black teatfish are in a perilous state of conservation globally. "The results of this study are a wake-up call to urgently increase their protection," she said. Steven Purcell, a professor of marine science and management at Southern Cross University, said the study underlined the need for better planning of fishery harvest strategies and conservation of the species. "Pacific Island fishers say this species is now rarely seen on their reefs, and Australia should take heed to avoid overfishing this resource too," he said.