Swordfish, turtle sightings off B.C. evidence of ocean warming: biologist
VANCOUVER — Sightings along the B.C. coast of a swordfish and loggerhead turtle — species normally associated with warmer waters — are the latest startling evidence of climate change.
Both species were spotted by biologist Luke Halpin while travelling aboard the Canadian Coast Guard research vessel John P. Tully during pelagic seabird and marine mammal surveys on the west coast. His findings were recently published online in the journal BioOne.
“None of these are in isolation,” he said in an interview. “It’s all indicative of warming trends. In the future, if this trend continues, and it likely will, we’ll see more and more of generally warm-water species occurring in B.C. waters.”
Halpin was under contract to the Canadian government at the time to conduct the surveys, but is currently earning his PhD at Monash University in Melbourne, Australia, based on petrel studies in the South Pacific.
He spotted the swordfish on Sept. 5, 2017, about 20 nautical miles from Brooks Peninsula on the west coast of Vancouver Island. He estimated its length at two to three metres.
“It was swimming against the current, just ahead of the ship,” he said. “To see it up close was a treat. I was lucky to get a photo.”
Sea surface temperature was 1.5 to 2.5 degrees Celsius above the expected average for September.
It is the first record of a swordfish along the B.C. coast. The only other sighting occurred in 1983 far offshore but still within Canada’s exclusive economic zone during a Canadian-Japanese test fishery for squid.
Halpin spotted the loggerhead turtle on Feb. 22, 2015, about 45 nautical miles west of Tofino — the first such sighting off the B.C. coast, although the species has been previously observed once in Washington state and twice in the Gulf of Alaska.
This loggerhead was estimated to be two-thirds of a metre in length and featured significant algae growth on its head and shell. In the North Pacific, the species nests almost exclusively in Japan, and is listed as endangered in the North Pacific under the U.S. Endangered Species Act.
In his paper, Halpin suggests the loggerhead may have “strayed north in a plume of warm water, subsequently becoming stranded in 10-degree C water in which it was likely unable to thermoregulate and suffered from ‘cold stunning.’ Most sea turtles wash onshore dead or moribund in autumn to early winter. The survival of this animal into February is unusual, and its fate is unknown.”
Sea turtles previously documented in B.C. coastal waters include the green, leatherback and Olive Ridley.