Southern right whale populations use the waters off of Peninsula Valdes, Argentina as a nursery ground. Until the year 2000, whale mortality appeared to increase at a rate similar to the population’s growth rate. However, more recently, this population has suffered the largest mortality event ever recorded for a baleen whale anywhere in the world. Extremely high mortalities recorded since 2007 include 314 dead whales, 76% of which were newborn calves. This mortality rate not only exceeds rates from the previous four decades by 170%, but its differential impact on calves is likely to have long-term consequences for the population. Determining the cause for these deaths is urgent– especially if the underlying problem is something people are doing to the system, something that can be addressed.

The WCS Southern Right Whale Health Monitoring Program was established in 2003 to understand the health threats faced by southern right whales that come to Argentina to breed and document drivers of mortality. However, the unexpectedly high mortality rates observed since 2007 have brought on a sense of urgency in terms of the future of the southern right whale population and other baleen whales around the world.

Thumbnail Southern right whale photo credit: Christian Samper, WCS

Banner Southern right whale tail photo credit: Julie Larsen Maher, WCS