Bottlenose dolphins typically reside in tropical or warm-temperate waters around the world — but researchers recently glimpsed a group of around 200 of the dolphins and around 70 false killer whales off northern Vancouver Island’s west coast in Canada. They said this sighting is “the only occurrence of common bottlenose dolphins recorded in Canadian Pacific waters” — and a warming trend could be to blame.

Bottlenose dolphins seen in Biscayne Bay, Florida

In July 2017, Halpin Wildlife Research, working with Canada’s Department of Fisheries and Oceans and Department of Environment and Climate Change, documented the dolphins and whales. In research published this month in the journal Marine Biodiversity Records, the three researchers involved said the sighting “is the most northerly record” for common bottlenose dolphins “in the eastern North Pacific.”

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Lead author Luke Halpin said in a statement, “The sighting is also the first offshore report of false killer whales in British Columbia. To see the two species traveling together and interacting was quite special and rare. It is known that common bottlenose dolphins and false killer whales seek each other out and interact, but the purpose of the interactions is unclear.”

Warming in eastern North Pacific waters between 2013 and 2016 could be the reason for the presence of the dolphins and whales. Halpin said he’s documented warm-water species in British Columbia waters since 2014, including a loggerhead turtle and a swordfish. He said, “With marine waters increasingly warming up, we can expect to see more typically warm-water species in the northeastern Pacific.”

+ BioMed Central

+ Marine Biodiversity Records

Images via Gregory “Slobirdr” Smith on Flickr and the National Park Service