UBC researchers imagine a bunch of killer whales noticed searching marine mammals together with sperm whales, in addition to a sea turtle, within the open ocean off California and Oregon could possibly be a brand new inhabitants.
Based mostly on out there proof, the researchers posit in a brand new research printed in Aquatic Mammals that the 49 orcas may belong to a subpopulation of transient killer whales or a novel oceanic inhabitants present in waters off the coast of California and Oregon.
“The open ocean is the most important habitat on our planet and observations of killer whales within the excessive seas are uncommon,” stated first writer Josh McInnes, a masters pupil within the UBC Institute for the Oceans and Fisheries (IOF).”On this case, we’re starting to get a way of killer whale actions within the open ocean and the way their ecology and behavior differs from populations inhabiting coastal areas.”
Three ecotypes of killer whale dwell alongside the coasts of California and Oregon: ‘residents’, ‘transients’, and ‘offshores’.
The unknown orcas have been noticed earlier than however the brand new paper incorporates a weight of proof gathered from 9 encounters with 49 animals from 1997 to 2021, sufficient to type a stable speculation, the researchers stated.
“It is fairly distinctive to discover a new inhabitants. It takes a very long time to collect images and observations to acknowledge that there is one thing totally different about these killer whales,” stated co-author Dr. Andrew Trites, IOF professor.
The 49 killer whales couldn’t be matched with any identified animals via images or descriptions. “In one of many first encounters researchers had with a pod of those oceanic killer whales, they have been noticed taking over a herd of 9 grownup feminine sperm whales, finally making off with one. It’s the first time killer whales have been reported to assault sperm whales on the west coast,” stated McInnes. “Different encounters embrace an assault on a pygmy sperm whale, predation on a northern elephant seal and Risso’s dolphin, and what seemed to be a post-meal lull after scavenging a leatherback turtle.”
Shark scars present important clue
A key clue to the brand new inhabitants’s presumed habitat vary lies in cookiecutter shark chew scars noticed on nearly all the orcas. This parasitic shark lives within the open ocean, which means the brand new inhabitants primarily inhabit deep waters removed from land.
The orcas additionally function bodily variations from the three primary ecotypes, together with of their dorsal fins and saddle patches — the gray or white patches by the fin. “Whereas the configurations and dimensions of the dorsal fins and saddle patches are just like transient and offshore ecotypes, the form of their fins diverse, from pointed like transients to rounded like offshore killer whales,” stated McInnes. “Their saddle patch patterns additionally differed, with some having massive uniformly grey saddle patches and others having easy slim saddle patches just like these seen in killer whales in tropical areas.”
Together with marine mammal inventory evaluation surveys, fishermen and passengers on an open-ocean birding expedition and whale-watching tour additionally supplied observations of the unidentified killer whales, stated Dr. Trites. Recognizing the brand new inhabitants has develop into one thing of a passion amongst fishermen, a few of whom have purchased cameras for his or her journeys particularly to snap an encounter, the researchers stated.
The researchers hope to doc extra sightings and collect extra data, together with acoustic knowledge concerning the orcas’ calls and genetic data from DNA samples to additional examine how these killer whales could differ, or not, from already documented populations.
