Researchers took a look at more than 60 years of taped interactions between Southern Resident killer whales (SRKW), a well-studied and little population of killer whales, and porpoises in the Salish Sea (an inland sea shared by Washington State and British Columbia) to comprehend their behavior. The SRKW are an endangered population.
For decades, whale (Orcinus whale), also understood as killer whales, have been seen bugging and even killing other marine mammals such as porpoises but not consuming them. In their study, Giles and her team identified and examined 78 occurrences of SRKWs bothering porpoises in between 1962 and 2020, of which 28 resulted in the porpoises deaths. Another possibility is that porpoise harassment might be for orcas to improve their salmon-hunting abilities. SRKWs could see porpoises as moving targets to practice searching, even if they didnt plan to consume them. Whats clear is that cetaceans arent part of the SRKWs diet.
For decades, whale (Orcinus whale), also referred to as killer whales, have been seen pestering and even killing other marine mammals such as cetaceans but not consuming them. This has puzzled researchers for decades. Now, a new research study might have discovered why, suggesting orcas may be playing, practicing to hunt, or attempting to provide care.
SRKWs were seen carrying the cetacean on their backs, or “carrying” the porpoise between multiple people, nearly looking like a “game” where the goal was to keep the cetacean out of the water. Sometimes SRKWs would continue engaging with the cetacean long after it had died, suggesting that killing was not actually the objective.
Regardless of these findings, Giles and the team of scientists acknowledge that the precise factor behind porpoise harassment can never be completely understood. Whats clear is that porpoises arent part of the SRKWs diet plan. These orcas generally eat salmon, particularly Chinook.
” I am frequently asked, why do not the Southern Residents just eat porpoises or seals instead?” Deborah Giles, study author, said in a news release. “Its since fish-eating killer whales have an entirely different ecology and culture from orcas that eat marine mammals– despite the fact that the two populations reside in the very same waters.”
The study also highlights the value of saving salmon populations throughout the whales entire variety. Preserving a supply of salmon is important for their survival and wellness. SRKWs are noted as threatened in Canada and the United States and are at danger of termination due to the scarcity of salmon, vessel disruption, and legacy pollutants.
A killer whale in the Salish Sea is observed harassing a porpoise. Image credit: Wild Orca.
Theres also a third alternative. Orcas might be trying to provide care for cetaceans that they perceive as weaker or ill, a manifestation of their natural inclination to take care of others in their group. This is called mismothering habits. Women have actually been seen bring their departed calves and have brought porpoises in a comparable method.
The research study was released in the journal Marine Mammal Science.
Salmon professionals
In their research study, Giles and her team identified and evaluated 78 incidences of SRKWs pestering porpoises between 1962 and 2020, of which 28 resulted in the cetaceans deaths. They suggested 3 possible factors for his habits, the very first being social play. Orcas are socially savvy and extremely smart, with a joyful and playful personality.
” Killer whales are extremely complicated and smart animals. We found that porpoise-harassing behavior has been handed down through generations and throughout social groupings. Its an incredible example of killer whale culture,” Sarah Teman, research study author said in a press release. “The culture of eating salmon is deeply deep-rooted in Southern Resident society.”
Three possibilities
” Mismothering habits, also referred to as displaced epimeletic behavior to scientists, may be due to their restricted opportunities to care for young,” Giles stated in a news release. “Our research has revealed that due to poor nutrition, almost 70% of SRKWs killer whale pregnancies have resulted in miscarriages or calves that passed away immediately after birth.”
Another possibility is that porpoise harassment might be for whales to improve their salmon-hunting abilities. SRKWs could see porpoises as moving targets to practice searching, even if they didnt mean to eat them. Adult women, the most skilled hunters, were involved in harassment the least, while calves and juveniles were included more.
