SUFB 025: Blue Whales’ Foraging Behavior

By October 8, 2015 October 21st, 2015 Speak Up For Blue Podcast


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Today I want to lighten the mood a little bit. Instead of talking about threats to our oceans, I want to talk about unique behaviors of marine critters. Specifically, I want to discuss the feeding behavior of the largest animal ever known to have existed. The blue whale, a cetacean that grows to about 30 meters long and 180 tons, must consume about 4 tons of krill to generate enough energy required get it through the day. This would be the equivalent of an average man and woman eating 10 pounds and 3 pounds per day, respectively. Pretty incredible stuff. However, there’s a bit of an issue with this. If a blue whale requires so much energy to keep itself going, and that energy requires consuming an immense amount of food, how does it allocate its current energy to search for food in the first place?

Well, a research team headquartered on the Pacific coast recently found the answer to that question. In the concisely-titled study “Blue whales (Balaenoperta musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density,” scientists gave evidence for a unique feeding behavior in blue whales obtained from multisensor digital tag data. The study clams that blue whales exhibit a complex feeding strategy to account for areas with fluctuating krill abundance.

When the whales are traveling through locations with low numbers of krill, they typically conserve oxygen by spending less energy searching for and consuming these krill. However, in areas with larger krill populations, the researchers show that blue whales exert more oxygen consuming these krill through behaviors like deep dives and rapid movements.  The key point here is that blue whales are not indiscriminate feeders like we previously believed, just gliding through the ocean eating any krill in their way. Rather, they strategically conserve energy in certain areas while expending a disproportionate large amount of energy in other, more krill-abundant areas. See, just talking about some pretty interesting research. Nothing sad about this post. Now let’s just give it a happy ending and call it a day.

Now, rising sea surface temperatures resulting from man-made climate change has already resulted in marine organisms shifting their distributions and migrating to cooler waters. If krill populations migrate as well, blue whales may not be able to adapt and locate this moving food source. They may continue to exert lots of energy in previously bountiful waters that are becoming more and more scarce. While there’s a chance that blue whales can match the krill’s migrations and continue to feed on this food source (happy ending!), the more time and energy they spend unsuccessfully searching for krill, the greater a chance there is of these cetaceans…starving to death.

Shoot. Sorry.

However, this just makes it more critical that we continue to address the impacts of climate change to mitigate any future harm to our ocean’s inhabitants.

I’ll do better next Thursday, promise.

Enjoy the podcast!

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