Blue, fin and humpback whales occupied waters with different nearby krill swarms in the Northern California Current. One peer-reviewed observational study combined shipboard sightings with acoustic prey measurements. Blue whales had the clearest habitat distinction, including shallower swarms. The associations help describe how the species share feeding grounds, while uneven samples and uncertain feeding activity constrain interpretation.
Krill swarms near blue whale sightings had a median depth of 101 metres, compared with 141 metres around humpbacks and 197 metres around fin whales. The contrast comes from one peer-reviewed observational study of the Northern California Current. Blue whales were associated with shallower swarms that were more evenly occupied by krill and contained a higher share of an energy-rich krill species. These measurements describe nearby prey habitat.[1]
Researchers combined visual whale detections with acoustic records gathered on 10 surveys between 2018 and 2024. They summarized 1,036 swarms across 313 areas, using prey measurements within 5 kilometres of sightings. The whale sample included 19 blue whale groups, 40 fin whale groups and 254 humpback groups. Swarm depth, species composition, occupancy and internal patchiness helped classify the habitats associated with the three whales.[1]
The blue whale habitat was easier to distinguish than those of fin and humpback whales, whose swarm characteristics overlapped more. Whale body size did not consistently predict the observed differences. The much larger humpback sample limits comparisons, and sightings could include animals travelling rather than feeding. In the final surveys, krill composition relied on an earlier distribution model. The associations therefore leave actual feeding decisions and causal mechanisms unresolved.[1]
