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Three different killer whale (Orcinus orca) ecotypes are known to inhabit the northeastern Pacific: residents, transients, and offshores. These ecotypes are distinguished by morphological, genetic, behavioral, and acoustic differences. Killer whales of each ecotype produce distinct, stereotypic pulsed calls that can be used as acoustic indicators of presence, making passive acoustic monitoring a useful method for assessing intraspecies differences in spatial and temporal patterns.