Tracking Offshore Killer Whales in Southern California (and Beyond!)

On 5 January 2013, researchers from Cascadia encountered a small group of "offshore" ecotype killer whales during a survey on the SOAR range, as part of the Marine Mammal Studies at SCORE project. While mammal-eating transient killer whales are occasionally sighted in the study area, this was the first sighting of offshores in the course of our work in Southern California. The whales were first detected acoustically on the SOAR hydrophone array by our collaborators from NUWC at the Range Operations Center on Coronado Island, who vectored the survey boat into the area to investigate vocalizations with an unusual click structure. The killer whales were widely dispersed and traveling slowly south through an area with many fin whales, and in fact the two species appeared interactive, often traveling and surfacing together. Four unique individuals were identified that day, and two location-tracking satellite tags were deployed. Upon returning to shore (San Clemente Island) identification photos were sent to local killer whale researcher Alisa Schulman-Janiger, who was able to quickly identify one of the adult males in the group as O215- a whale sighted sporadically in Central California since 1999 (thanks Alisa!).

Offshore killer whale O215 with satellite tag.

Bad weather kept the team ashore the next two days, while the satellite tagged whales traveled south to just over the Mexican border, then turned around. On 8 January the wind let up and the group was encountered again as they transited past the west side of the island in a big rolling swell, again associated with a number of fin whales. This time the whales were a little less dispersed, though still spread over a kilometer or more, and additional group members were identified, though we believe the total number of whales present was likely less than 10. A satellite tag was deployed on O215 which is recording the whale's diving behavior in addition to its movements, hopefully providing some of the first insights into subsurface behavior for this ecotype of killer whales.

The map above shows the movements of one of the tagged offshore killer whales over a 5 day period (highest quality locations only). The group was first encountered on January 5th west of San Clemente Island traveling south, then re-encountered on January 8th as they moved north back into the same area. As of the end of the day January 10th, they were heading southwest across Tanner and Cortez Banks.

After this, the whales left southern California and began making their way north, generally following the shelf edge and thus remaining well offshore. On February 17th they briefly crossed paths a tagged southern resident killer whale from K Pod (see Cascadia's Facebook page for details), which was southbound inshore off Cape Mendocino in Northern California. By the end of February they were off Northern Washington, and on March 4th they turned inshore just south of the Queen Charlotte Islands in northern British Columbia- just in time to intersect with a Department of Fisheries and Oceans Canada marine mammal survey. They resighted, and photo-identified, the second tagged male as O358 (thanks to Robin Abernethy and John Ford for follow up photos and the ID!). The tags have begun to duty cycle, transmitting less frequently to conserve battery life and hopefully extend the total duration over which the whales can be tracked. The tag on O215 is only occasionally updating, and interestingly it now appears that he separated from O358 off Northern Washington, and has since returned to northern Oregon. Updated maps from both tagged whales are provided below.

(Left) O215 (102464), off northern Oregon, having separated from O358 (94815) during a pause in transmissions. (Right) 10 days of movements from O215 (94815) as he shifted inshore in northern British Columbia, and then transited up the inside passage to Southeast Alaska, near Ketchikan.

For additional information please contact Greg Schorr (gschorr@cascadiaresearch.org) or Erin Falcone (efalcone@cascadiaresearch.org)

Updated 7 March 2013.

Photographs on this page (c) Cascadia Research, use only with permission

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