Southern resident killer whales do not lack summer prey: UBC researchers

Researchers on the University of British Columbia say they’ve “debunked” a standard perception that southern resident killer whales lack summer time prey in Canadian waters.

The endangered orcas feed on Chinook salmon, lengthy thought to have been scarcer in the course of the summer time of their feeding grounds than in these of their extra populous cousins, the northern resident killer whales.

Scientists now say the numbers of Chinook salmon within the Salish Sea throughout summertime are 4 to 6 instances extra ample for southern residents than in northern resident feeding grounds.

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“Individuals have been speaking a few prey scarcity as if it’s a reality, however that is the primary research to quantify and evaluate the quantity of their most popular prey, Chinook salmon, accessible to southern and northern resident killer whales,” stated lead creator Mei Sato, a analysis affiliate on the UBC Institute for the Oceans and Fisheries on the time of the research, in a UBC information launch.

The report published Tuesday within the Canadian Journal of Fisheries and Aquatic Sciences in contrast Chinook availability for southern residents within the Juan de Fuca Straight with availability for northern residents within the Johnstone Strait between 2018 and 2019.

Utilizing sonar, researchers discovered that the sizes and distributions of the fish have been comparable in each areas, however there have been many extra fish “research areas” of the Juan de Fuca.

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Because it stands, scientists consider there are about 73 southern resident killer whales left on the earth, and a rising inhabitants of round 300 northern residents, that are threatened, however not endangered.

The thinner stature of the southern residents could have contributed to the idea they’ve much less summertime prey, stated Sato, however the brand new analysis means that meals scarcity is “in all probability not occurring” after they feed within the Salish Sea in the summertime.

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The analysis didn’t consider different elements that may stop southern residents from really catching their prey, like elevated vessel visitors and noise of their conventional feeding grounds.

Sato and research co-author Andrew Trites, director of the UBC Marine Mammal Analysis Unit, each say analysis efforts ought to now deal with different seasons and elements that impression Chinook availability.

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“To reply the query of whether or not there’s an total prey scarcity, we nonetheless want to determine what’s occurring throughout winter and spring,” stated Sato, “whether or not there are vital fluctuations year-to-year and within the totally different areas these whales journey to, like California.”

The analysis was funded by Fisheries and Oceans Canada, and carried out with assist from sport and business fisherman, the Sport Fishing Institute of B.C. and several other whale watching firms.