IWC Extinctions Initiative

According to the IUCN Red List a species or subspecies is considered Extinct (EX) when there is no reasonable doubt that the last individual has died.  A species or subspecies is presumed Extinct when exhaustive surveys in known and expected habitat have failed to record a single individual.

Distinct populations can also become locally extinct.  A single species is often made up of several separate populations and one population may be eradicated whilst others continue to live.  For example, the North Pacific gray whale population in the eastern North Pacific is considered healthy, but the western population is critically endangered.

Extinction is a natural phenomenon, but current rates of extinction are much higher than historic ‘background rates.’  The lifespan of a species varies depending on a number of factors such as body size and geographic range.  Many cetacean species are assessed to have survived between 5 and 30 million years. Today’s increased rates of extinction are due to human activities and associated habitat disruption and climate change.

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, assesses the conservation status of most plant and animal species, some subspecies, and some subpopulations.  They use a rigorous approach to assess all available data for each species against defined criteria, and classify each into one of the IUCN Red List status categories