Extreme longevity revealed by 24-year genetic mark-recapture challenges conservation of endangered sea cucumbers.

Coral reef sea cucumbers are heavily exploited despite the precarious conservation status of many species, yet limited life-history knowledge constrains effective management. We used genetic mark-recapture to estimate longevity, mortality, and growth in the endangered, CITES-listed black teatfish Holothuria (Microthele) whitmaei by resampling a population after 24 years. Most individuals (60%) in 2024 were genetically identical to those sampled in 2000, indicating extremely low adult mortality (∼0.04 per year), a conservative mean lifespan of ∼24-27 years, and longevity exceeding 100 years. Most recaptured individuals showed negligible or negative growth. Current harvest models for tropical sea cucumbers do not account for such extreme longevity and likely overestimate sustainable yields. Our results suggest that exploitation of long-lived reef invertebrates is unsustainable under prevailing harvest rates and environmental stress, highlighting the need to reassess productivity-based fisheries frameworks more broadly.