Baleen whale prey consumption based on high-resolution foraging measurements

Area of Science:

• Marine biology
• Ecosystem dynamics
• Quantitative ecology

Background:

• Baleen whales are crucial ecosystem engineers due to their high prey consumption and nutrient recycling.
• Accurately quantifying whale feeding rates and ecosystem impact has been challenging.
• Previous estimates relied on unvalidated metabolic models for large whale species.

Purpose of the Study:

• To empirically measure baleen whale feeding rates and prey consumption across different ocean basins.
• To compare new consumption estimates with previous model-based extrapolations.
• To assess the historical and current role of baleen whales in nutrient cycling and ecosystem productivity.

Main Methods:

• Deployment of tags on 321 individuals across seven baleen whale species.
• Integration of acoustic prey density measurements with tag data.
• Calculation of prey consumption at daily to annual scales in the Atlantic, Pacific, and Southern Oceans.

Main Results:

• Baleen whale prey consumption was underestimated by threefold or more in some ecosystems compared to previous studies.
• Pre-whaling mysticetes in the Southern Ocean consumed an estimated 430 million tonnes of Antarctic krill annually.
• Pre-whaling nutrient recycling (e.g., iron) was tenfold higher in the Southern Ocean than current levels.

Conclusions:

• Baleen whale populations play a larger role in marine ecosystems than previously understood.
• The recovery of baleen whales is essential for restoring ecosystem productivity and function.
• Nutrient recycling by whales significantly influences marine food webs and biogeochemical cycles.