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Whale Poop is essential for the world – says study

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Blue whales, which are bigger than any dinosaur ever, can grow to a length of 110 feet and a weight of 190 tons.

The baleen whales, which include the humpback and grey whales, are all members of the cetacean family. As a group, they are among the largest creatures on Earth.

You might think that creatures of this size consume a lot of food. However, new evidence reveals that baleen whales eat three times more than previously thought.

They poop more as a result of this. And scientists say that this is great news for the rest of us.

The study was published in the journal Nature on Wednesday.

Baleen whales eat small fish and crustaceans, especially krill, in clusters. In turn, whale poop is an important source of nutrients for ocean ecosystems.

However, because of their size and feeding habits, it’s been difficult to estimate how much food they eat. Conservation efforts have been hampered as a result of this.

“If we want to protect whales and make sure they are thriving in modern oceans, then knowing how much food they need to survive and reproduce is critical,” says lead author Matthew Savoca, a postdoctoral scholar at Stanford University.

Previous estimates were likely off because they relied on metabolic models based on much smaller species examined in captivity, such as dolphins, or were based on the contents of dead whales’ stomachs.

“Occasionally when whales were killed, people would open their stomachs and weigh the contents inside,” adds Savoca.

This research team, on the other hand, employed direct measurements of baleen whales in the Atlantic, Pacific, and Southern Oceans to figure out how much krill they ate and then defecated. Researchers collected field data on more than 300 baleen whales from seven different species using tagging technologies and acoustic assessments.

Scientists assessed the amount of prey (such as swarms of krill) eaten by the whales, as well as the number of nutrients recycled back into the ocean through excrement, based on their observations of daily feeding activity.

Baleen whales are thought to ingest less than 5% of their body weight each day, according to previous research.

Instead, according to Savoca’s findings, baleen whales devour three times more prey than previously thought.

Whales tend to consume 5 to 30% of their body weight per day across all baleen whale species studied. Fin whales and humpback whale populations in the northern Pacific Ocean alone require more than two metric tons of krill each year, according to the researchers.

The amount and type of prey consumed, however, is determined by the whale. On feeding days, an adult eastern North Pacific blue whale (Balaenoptera musculus), for example, will eat 16 tons of krill, but a North Atlantic right whale will likely take five tons of tiny zooplankton.

Meanwhile, humpback whales prefer a more complex diet that includes both anchovies and krill. All of this food equates to a lot more excrement.

“In brief, if whales eat more than we thought, then they also recycle more nutrients — i.e. poop — than we thought,” says Savoca.

WHY DO THESE RESULTS MATTER?

The researchers weren’t just trying to figure out how much whales eat and poop for the sake of it.

“While it may just seem like a fun trivia fact, knowing how much whales eat is an important aspect of ecosystem function and management,” says Savoca.

In ocean ecosystems, whales play a vital role in nutrient recycling. When they poop, they return nutrients to the water, including iron. Smaller ocean animals, such as phytoplankton, take these nutrients, which helps to maintain oceans healthy.

According to Savoca:

“It’s not that these whales add more iron —or other nutrients — to the system, they just convert it from within the bodies of their prey, to in the seawater itself, where it could, in theory, fertilize phytoplankton — the base of all open ocean food webs.”

However, while whale poop has a huge impact on worldwide ocean ecosystems, new research reveals that the loss of whales has slowed the global nutrient recycling conveyor belt.

Between 1910 and 1970, baleen whale populations plummeted due to commercial whaling. As a result, the remaining whales ate less prey than they could have, recycling less nutrients.

Baleen whales in the Southern Ocean had 430 million tons of Antarctic krill annually until the 1900s, according to the study. That’s twice as much krill as there is now.

“Baleen whales were maintaining the krill stocks on which they were feeding,” says Victor Smetacek, the author of a related perspective on the study.

“It all collapsed when the whales were taken out,” Smetacek said.

This new research underlines whales’ vital yet vulnerable role in ocean ecosystems, especially given that scientists know baleen whales contribute far more to these ecosystems than previously thought.

Although certain baleen whale species, such as the humpback whale, have made amazing comebacks in recent years, others have not.

Savoca thinks that his research will bring attention to the ecological importance of baleen whales and boost conservation efforts. Simple improvements, such as restrictions slowing shipping traffic along frequent whale routes, can have “big positive effects,” he says.

“We are trying to use the information we have learned to try and conserve whales, and help them recover,” Savoca says.

Image Credit: Getty

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