For decades, scientists have been intrigued by Pacific Northwest fish-eating killer whales harassing and killing porpoises without eating them. Researchers Deborah Giles of Wild Orca and Sarah Teman of the SeaDoc Society conducted a study, analyzing over 60 years of interactions between Southern Resident killer whales and porpoises in the Salish Sea to decipher this behavior. These whales, now endangered with only 75 individuals, rely heavily on Chinook salmon, also endangered, for survival.

This study, covering 78 incidents from 1962 to 2020, proposes three reasons for the whales' behavior towards porpoises: social play, hunting practice, and mismothering behavior, where whales possibly care for porpoises as they would for their own young. The latter theory is supported by the high rate of miscarriages and neonatal deaths among these whales, possibly driving them to exhibit care towards other species. However, porpoises remain outside their diet, which is specialized for salmon.

Despite these new insights, the exact reason behind the whales' behavior towards porpoises remains elusive. What's clear is their diet is focused on salmon, and their culture doesn't include eating porpoises. This underscores the importance of conserving salmon populations for the survival of Southern Resident killer whales and the health of the Salish Sea ecosystem.

Separately, a population of killer whales in the Iberian Peninsula has been interacting with boats, highlighting the diverse cultures among killer whale populations. The Southern Resident killer whales and Iberian Peninsula orcas exhibit distinct behaviors, but they may share an affinity for play. The study, funded by various organizations, emphasizes the complexity of killer whale culture and the need for ongoing research and conservation efforts.