Study Reveals Influence of Krill Availability on Humpback Whale Pregnancies
Published:09 Feb.2023    Source:ScienceDaily

 The study, published January 15 in Global Change Biology, is based on eight years of data on humpback whale pregnancies (2013 to 2020) in waters along the Western Antarctic Peninsula, where krill fishing is concentrated.

Lead author Logan Pallin said the study demonstrates for the first time the link between population growth and krill availability in Antarctic whales. This is significant because until now, it was thought that krill were essentially an unlimited food source for whales in the Antarctic. Continued warming and increased fishing along the Western Antarctic Peninsula, which continue to reduce krill stocks, will likely impact this humpback whale population and other krill predators in the region. This information is critical as we can now be proactive about managing how, when, and how much krill is taken from the Antarctic Peninsula. In years of poor krill recruitment, we should not compound this by removing krill from critical foraging areas for baleen whales.
Coauthor Ari Friedlaender said the Western Antarctic Peninsula is experiencing some of the fastest climatic warming of any region on the planet. Krill supplies vary depending on the amount of sea ice. In years with less sea ice in the winter, fewer juvenile krill survive to the following year. The impacts of climate change and likely the krill fishery is contributing to a decrease in humpback whale reproductive rates in years with less krill available for whales.
Coauthor Chris Johnson said this research shows that highly precautionary management measures are needed to protect all Antarctic marine life that depends on krill for its survival. "Krill are not an inexhaustible resource, and there is a growing overlap between industrial krill fishing and whales feeding at the same time," Johnson said.