More than 300 Right whales have died off Argentina since 2005

A mother and calf pair of southern right whales in the waters of coastal Patagonia. Credit: G. Harris/Wildlife Conservation Society

March 2010. To answer that question, a team of whale and health experts from the Wildlife Conservation Society(WCS) joined experts from other organizations at a workshop sponsored by the International Whaling Commission on the Patagonian coast of Argentina to try and solve a perplexing and urgent mystery.

At issue is the long-term conservation of the southern right whale, one of the world's great conservation success stories and the focus of a thriving eco-tourism industry along Argentina's Patagonian coast. Over the past five years, health experts from WCS and biologists working around the famed Península Valdés -an important calving ground for right whales and a World Heritage Site-have recorded an alarming increase in the number of dead right whale calves.

The workshop- hosted by the Centro Nacional Patagónico (CONICET)-was held in Puerto Madryn in Chubut Province in March in an attempt to identify the possible causes of the die-off and formulating conservation recommendations and future research to better understand them.

Calf mortality
"We need to critically examine possible causes for this increase in calf mortality so we can begin to explore possible solutions," said Dr. Marcela Uhart, associate director of WCS's Global Health Program and one of the early founders of the program that discovered the problem. "Finding the cause may require an expansion of monitoring activities to include the vast feeding grounds for the species."

Southern right whales Growing up to 55 feet in length and weighing up to 60 tons, the southern right whale is now the most abundant species of right whale in the world. Unlike the North Atlantic and North Pacific right whales (both of which number in the low hundreds), southern rights have managed to rebound from centuries of commercial whaling, with populations growing at approximately seven percent annually since 1970. Of the estimated total population of southern right whales found throughout the entire Southern Hemisphere, around one third use the protected bays of Península Valdés as a calving and nursing habitat between the months of June and December. Photo credit Wildlife Extra.

308 dead whales - Mostly calves
Since 2005, a total of 308 dead whales were recorded in the waters around Peninsula Valdés, 88 percent of which were calves less than three months old. The deaths constitute 28 percent of live calf sightings during that period.

Unusually thin blubber
Examination of samples taken from the beached whale calves ruled out many of the suspected causes, and some have revealed unusually thin blubber layers.

In 2009, the Scientific Committee of the IWC identified the die-off as a management priority, prompting the organization of the workshop.

Peninsula Valdes
"Península Valdés is one of the most important calving and nursing grounds for the species found throughout the Southern Hemisphere," said Dr. Howard Rosenbaum, director of the WCS's Ocean Giants Program and a member of the IWC's Scientific Committee. "By working with the government of Argentina, the Province of Chubut, the IWC, and our diverse team of experts and specialists, we can increase our chances of solving this mystery, the critical next step to ensuring a future for this population of southern right whales."

Workshop participants will consider a number of hypotheses on the cause or causes of calf mortalities such as: biotoxins; disease; environmental factors at their nursing grounds; and potential variations in prey availability at the whales' distant feeding grounds.

The Wildlife Conservation Society's Global Health Program helped establish the Southern Right Whale Health Monitoring Program, a consortium of NGOs that has recorded an increasing number of whale calf mortalities in Golfo San José and Golfo Nuevo, located on the north and south of Península Valdés. Other members of the monitoring program include: the Ocean Alliance / Whale Conservation Institute (OA/WCI); Instituto de Conservación de Ballenas (ICB); Fundación Patagonia Natural (FPN); and Fundación Ecocentro.

The workshop also includes participants from: the Centro Nacional Patagónico; the Zoological Society of London; the National Oceanic and Atmospheric Administration (NOAA); the World Conservation Union (IUCN); the Woods Hole Oceanographic Institution; the British Antarctic Survey; the Marine Mammal Center; the U.S. Marine Mammal Commission; and other local and international organizations.