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An infographic displaying the variations between the three orca ecotypes that reside alongside the coasts of California and Oregon and the potential distinctive inhabitants. Credit score: UBC
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An infographic displaying the variations between the three orca ecotypes that reside alongside the coasts of California and Oregon and the potential distinctive inhabitants. Credit score: UBC
UBC researchers consider a gaggle 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 examine printed in Aquatic Mammals that the 49 orcas might belong to a subpopulation of transient killer whales or a singular 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 grasp’s pupil on 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 conduct differs from populations inhabiting coastal areas.”
Three ecotypes of killer whales reside 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 kind a strong speculation, the researchers stated.
“It is fairly distinctive to discover a new inhabitants. It takes a very long time to collect photographs and observations to acknowledge that there is one thing completely 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 by means of photographs or descriptions. “In one of many first encounters researchers had with a pod of those oceanic killer whales, they had been noticed taking up 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 clues
A key clue to the brand new inhabitants’s presumed habitat vary lies in cookie-cutter shark chunk scars noticed on virtually the entire orcas. This parasitic shark lives within the open ocean, that means the brand new inhabitants primarily inhabits deep waters removed from land.
The orcas additionally function bodily variations from the three important ecotypes, together with of their dorsal fins and saddle patches—the grey or white patches by the fin.
“Whereas the configurations and dimensions of the dorsal fins and saddle patches are much 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 much 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 offered observations of the unidentified killer whales, stated Dr. Trites. Recognizing the brand new inhabitants has turn out to be 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 info, together with acoustic information concerning the orcas’ calls and genetic info from DNA samples to analyze additional how these killer whales might differ, or not, from already documented populations.
Extra info:
Josh D. McInnes et al, Proof for an Oceanic Inhabitants of Killer Whales (Orcinus orca) in Offshore Waters of California and Oregon, Aquatic Mammals (2024). DOI: 10.1578/AM.50.2.2024.93