Is there enough prey for beluga whale survival?
The waters of Alaska’s Cook Inlet appear ideal for whales survival, but the beluga population there is critically endangered. And despite years of conservation efforts, their numbers stubbornly refuse to bounce back.
A recent study has uncovered an important clue: belugas need much more energy (and therefore, fish) for their routine behaviors.
Metabolic rate of whales
The researchers focused on the metabolism rates of Cook Inlet belugas. They aimed to decode the energy dynamics that sustain these majestic creatures through their daily and seasonal cycles.
“We consider the balance between calories in and calories out (that is metabolic balance) a key factor for survival in beluga whales,” explained Dr. Terrie Williams, lead researcher from the University of California-Santa Cruz (UCSC).
“It is the basis of understanding the biological machinery that drives large mammals.” This balance is delicate, easily tipped by external pressures.
Human activities and beluga survival
The impact of human activity on these marine inhabitants is profound. “As humans, we are impacting both sides of the calorie picture for this population – responses to shipping, oceanic noise, and other human activities as well as climate change drive up the metabolism and caloric needs of the whales.”
“At the same time, competition for fish makes finding enough calories to satisfy the caloric needs disrupts the overall balance in energy. Think of it as a gas tank of a car that has run out of fuel, or an athlete that has hit the wall,” explained Dr. Williams.
“NOAA is using these data to help predict and prevent the beluga population in Cook Inlet from reaching that critical metabolic failure.“
Metabolism of beluga whales
The researchers investigated energy management in Beluga whales by examining their behavior both during rest and activities like swimming. They measured oxygen consumption using a method called open-flow respirometry to analyze whales metabolic rate.
All animals including Beluga whales need a certain amount of energy to maintain basic body functions, even at rest. The study showed that this basic energy need of Beluga whales is similar to other cold-water mammals of comparable size. However, belugas use around twice the energy swimming compared to resting.
Beluga’s energy balance and survival
The study confirms that beluga whales must have enough fish to fulfill their high energy demand, especially while swimming. If they cannot successfully hunt, it can disrupt their energy balance.
This imbalance could negatively impact their ability to reproduce, fight off diseases, and ultimately lead to their survival. “This study is important in demonstrating how an animal is built – that is, its evolutionary building blocks – may make it vulnerable to population declines and put it on a road to extinction,” said Dr. Williams.
“The approach and the models developed here can be applied to many dolphins and whales around the world.”
Collaborative conservation efforts
“We are already using the data from the belugas to assist in our efforts to conserve narwhals, the iconic unicorn of the seas, whose populations have declined in eastern Greenland and is facing increasing human threats in western Greenlandic waters as increasing human activities are occurring with the melting of Arctic ice.”
“One of the most important aspects of this study was the integration of experts and unique resources from academia (UCSC), the zoological community (Georgia Aquarium), and federal agencies (NOAA) to come to the aid of an endangered species. “
“Collectively, we enabled the species to help save itself. Were that we could do that for all of the endangered and threatened species of the world!”
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