CONICET | Buscador de Institutos y Recursos Humanos

Southern right whales (Eubalaena australis) have experienced high mortality rates at Península Valdés, Argentina in recent years (Rowntree et al., 2013). In 2003, the Southern Right Whale Health Monitoring Program was established by a consortium of NGOs to monitor the health status of this population by post-mortem examinations. Previous reports to the IWC included information on the mortalities through 2013. Here we update information for the 2014-2015 seasons. A total of 737 dead whales were recorded on the Península Valdés calving ground and surrounding areas along the Argentine coast since 2003. The number of dead whales was 23 in 2014 and 42 in 2015. As in previous years, most of the dead whales were newborn calves (87% of strandings in 2014 and 90% in 2015; 89% for both years combined). More dead whales were recorded in Golfo Nuevo (74% in both years) than in Golfo San José (22% in both years). One stranded whale was found in the outer coast of the peninsula in both 2014 and 2015 (4 and 2% of total annual strandings, respectively), in addition to 1 (2%) near the city of Rawson (to the south of Península Valdés) in 2015. Most whales died in August ? September (65%) in 2014, and in July ? August (60%) in 2015. All whales were dead when reported or found, and post mortem examinations were performed when and to the extent that carcass condition allowed. Biotoxins, infectious diseases, malnutrition, the physiological and behavioral effects of Kelp Gull (Larus dominicanus) attacks on newborn calves and density-dependent processes have been proposed as hypotheses to explain the high calf mortalities in this calving ground (IWC 2011, 2015). Results on biotoxins (Wilson et al., 2015), Kelp Gull lesions (Marón et al., 2015a) and post-mortem findings on tissues and organs (McAloose et al., 2016) have been published recently by the Southern Right Whale Health Monitoring Program researchers and collaborators.