Harbour porpoises are flexible predators displaying context dependent foraging behaviours

Opportunistic mobile predators can adapt their behaviour to specific
foraging scenarios, allowing them to target diverse prey resources. An
interesting example is the harbour porpoise (Phocoena phocoena), a marine
mammal with a huge energy demand feeding on a large variety of fish, squid
and shrimps. Little is known about the foraging behaviour of harbour
porpoises, as observations of wild specimens are notoriously difficult to
obtain. In this study, foraging was identified in almost 60% of videos
from UAV recordings in Danish coastal waters during daylight hours.
Observations reveal them to be flexible predators, foraging on both single
fish and schools of fish, as well as individually and in groups of varying
size. We argue that some of the observed behavioural adaptations and
context-dependent strategies for prey capture are based on information
transfer and social learning. Our results provide unprecedented insights
into the foraging behaviour of an opportunistic mammalian predator.
Further, this study highlights the importance for porpoises to have access
to coastal areas for energy acquisition, where they are in conflict with
anthropogenic disturbances such as fisheries with the risk of by-catch.