Since June, more than 300 southern right whale (Eubalaena australis) calves have died in Argentine Patagonia, in what scientists describe as an "exceptional" die-off. The preliminary figure already far exceeds the previous annual record set in 2012, when 113 southern right whale calves died — the highest number ever documented for the species, both locally and globally.Now, scientists are racing to figure out exactly what's causing the record-breaking die-off. Laboratory analyses of specimens that died this year tested positive for the pathogenic bacterium Erysipelothrix rhusiopathiae, environmental authorities in Chubut province told Live Science. E. rhusiopathiae was first identified in so...