IUCN Red List Assessment
Red List Category Year Assessed
Critically Endangered Red List Criteria
Jefferson, T.A., Karczmarski, L., Kreb, D., Laidre, K., O’Corry-Crowe, G., Reeves, R.R., Rojas-Bracho, L., Secchi, E., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. Reviewer/s
Brownell Jr., R.L. & Cooke, J. (Cetacean Red List Authority) Contributor/s Justification
This subpopulation is considered Critically Endangered D. Using a proxy value of 54% for the mature adult proportion of the total population (based on calculations from the age of first reproduction (8 years), interbirth interval (2.5 years) and oldest age of reproductive females (30 years) in Sotalia fluviatilis
(see Taylor et al.
2007) – a species that lives in similar habitat (i.e., large river) and has similar, but better-known, life history characteristics), there are only 31-42 (total, all ages: 59-79) mature animals in the Mahakam subpopulation of Irrawaddy dolphins. Recent live-captures and ongoing bycatch in fishing gear are the factors likely most responsible for the subpopulation’s decline to such small numbers, and these threats still exist (Kreb et al