Local extinction of an isolated dugong population near Okinawa Island, Japan
説明
<jats:title>Abstract</jats:title> <jats:p>A small animal population becomes extinct owing to demographic and environmental stochasticity after declining below the minimum viable population (MVP). However, the actual process of extinction derived by stochastic factors after crossing MVP has not been recorded for long-lived marine mammals. Here, we reconstructed the extinction history of a small, isolated population of dugongs in Okinawa over 125 years. The initial population size of 300 in the 19th century declined to 50 in 1916 (because of overfishing), 20 in 1979, 10 in 1999, 3 after 2006, and finally extinct in 2019. After 1979, a decline in the natural growth rate for only 20 individuals led to extinction. Long-lived animals fall below the MVP; thus, active conservation measures should have been taken much sooner than when the actual extinction happened.</jats:p>