Drone footage of grey whales captured over seven years off the Oregon coast has revealed new particulars about how the enormous marine mammals discover and eat meals.
The findings, described in two research printed over the summer season, embrace that grey whales depend on totally different swimming methods to gather meals primarily based on their dimension and age, and that bigger whales usually tend to exhale “bubble blasts” to assist them keep underwater.
“Before this research, we thought that any whale used any of these behaviors,” stated Clara Bird, the lead writer of each research and a researcher at Oregon State University’s Marine Mammal Institute. “No one actually thought that there was a sample in who used which habits.”
Bird’s analysis additionally discovered that whales use totally different consuming methods primarily based on the depth of the water through which they seek for meals and the habitat of their prey. Such info may help future conservation efforts, she stated, as a result of it gives perception into the forms of habitats which may should be protected with the intention to protect the whales’ entry to meals.
“While proper now we’re not actively attempting to guard particular habitats, it’s actually essential to know that whales of various ages won’t be all utilizing the identical habitat for future considerations,” Bird stated. “It’ll assist us handle them shifting ahead.”
A section of the grey whale inhabitants is listed as endangered below the Endangered Species Act. The whole species as soon as confronted a danger of extinction because of industrial looking. Once widespread throughout the Northern Hemisphere, grey whales at the moment are frequently seen solely within the North Pacific. Just below 27,000 of them had been estimated to be within the space as of 2016, in keeping with a 2020 report from the National Oceanic and Atmospheric Administration.
The whales eat amphipod crustaceans like tiny shrimp and worms, which they eat by sucking up water and sediment from the seafloor, the place such creatures stay, then utilizing their baleen to filter the meals. Gray whales are usually noticed alone or in small teams, although giant teams could also be seen at feeding or breeding grounds.
Bird and her workforce performed their analysis off the coast of Newport. On crusing journeys over seven years, the group tracked and recorded particular person whales through drones. They recognized specific whales utilizing distinguishing markers like scars, spots or tail form.
The first research ensuing from that work, printed within the journal Animal Behaviour in July, targeted on variations within the whales’ foraging habits relying on their dimension and habitat.
The workforce tracked 78 grey whales throughout a complete of 160 sightings from 2016 to 2022. In the drone footage, they noticed that youthful, smaller whales usually swam sideways or going through ahead, opening and shutting their mouths in an try to search out and soak up meals. Older, larger whales, in the meantime, tended to dive then keep in place head-down in what the scientists described as a “headstand approach.”
The chance of such headstands elevated as a whale bought larger, the research discovered, whereas the chance of the forward-swimming tactic decreased. Water depth and the kind of habitat — rocky, sandy or coral reef — additionally performed a task within the method the whales took.
Bird attributes the swap between methods to the maturity of a whale’s muscular tissues in addition to its ranges of power and coordination.
Her workforce’s second research, printed within the journal Ecology and Evolution in August, described how older, larger whales launch air from their blowholes to assist them keep underwater when looking for meals.
These “bubble blasts” will help a whale sink by reducing their buoyancy. Bigger whales have a larger want for this, since their bigger lungs maintain extra air and so they have extra blubber, each of which make them susceptible to floating.
The discovering was primarily based on observations of 75 whales. On common, a bubble blast got here 27 seconds after a whale dove for meals, and most had been noticed whereas the whales had been doing headstands. The older and larger a whale bought, the larger the chance of such a blast.
“This form of pairing of the dimensions with the habits on the person stage is a extremely thrilling a part of this research,” Bird stated.
Susan Parks, a biology professor at Syracuse University who has printed research on whales’ consuming habits however was not concerned within the new analysis, stated that documenting range amongst one whale species helps scientists keep away from inaccurate generalizations.
“As we attempt to do conservation efforts or preserve endangered species, it’s actually essential to grasp that there may very well be a large variation in behaviors,” Parks stated. “So we will’t simply form of cease on the single commentary.”
Parks additionally highlighted the potential drones have for amassing detailed knowledge on whales.
“There’s a lot unknown about their habits,” she stated, including that the research reveals how “utilizing drone footage to basically spy on what the whales are doing gave them a completely totally different perspective on the small print of how they had been making a dwelling.”