Multi-year presence of humpback whales in the Atlantic sector of the Southern Ocean but not during El Nino

Humpback whales are thought to undertake annual migrations between their low latitude breeding grounds and high latitude feeding grounds. However, under specific conditions, humpback whales sometimes change their migratory destination or skip migration overall. Here we document the surprising persistent presence of humpback whales in the Atlantic sector of the Southern Ocean during five years (2011, 2012, 2013, 2017, and 2018) using passive acoustic data. However, in the El Nino years 2015 and 2016, humpback whales were virtually absent. Our data show that humpback whales are systematically present in the Atlantic sector of the Southern Ocean and suggest that these whales are particularly sensitive to climate oscillations which have profound effects on winds, sea ice extent, primary production, and especially krill productivity. Schall et al. use passive acoustic recordings of humpback whale calls to report the presence of humpback whales in the Atlantic sector of the Southern Ocean between 2011 and 2018. This serves as the first long-term report of humpback whales on a Southern Ocean feeding ground, and their notable absence during the El Nino years of 2015 and 2016 indicates that the inter-annual variability in their acoustic presence is driven by large-scale climate variability.

Automated summary

The study found that humpback whales were consistently present in the Atlantic sector of the Southern Ocean between 2011 and 2018, but were virtually absent during the El Nino years of 2015 and 2016. This indicates that humpback whales are particularly sensitive to climate oscillations.