Humpback Whales Make Amazing Comeback: Climate And Diet May Be Key
A bit of learning for a Saturday. Why turn on the TV when BMEWS can bring you the latest bits of science and nature to help you entertain your 4 year old? This is from an email I got from Knowledge News. Sign up for just $39 you can get access to all sorts of interesting stuff, forever.
Species Safety In Numbers?
Whale watchers worldwide got a bit of good news this week, with the release of a new study that says humpback whales are making a comeback in the North Pacific.
According to the study, the number of whales in the North Pacific may have reached 20,000 for the period between 2004 and 2006. That’s up from a total of fewer than 1,500 whales 40 years ago, when humpback hunting was banned.
Experts still worry that some humpback subgroups are taking longer to bounce back, but one described the news as “definitely very encouraging in terms of the recovery of the species.” It’s certainly enough to make us want to dive in for a closer look at one of the ocean’s marvelous mammals.
Other experts are thrilled that the humpback’s number have increased so dramatically, and wonder weather climate change and dietary change may have something to do with it. “A humpback cow only calves once every 7 years. She gives birth to a single calf, and that calf isn’t ready to breed until she’s 10 years old. Considering the standard rate of infant mortality among even the higher mammals in the wild, something unusual must be going on. To get these kind of numbers in just 40 years means that not only are the females surviving more than we expected, they must be growing faster and breeding younger. Slightly warmer seawater from climate change means the whales have to spend less energy to stay warm, and that helps. But that isn’t enough; they must be getting much higher levels of protein in their diets than you would normally get from eating a ton or so of krill every day.”
Uproarious Rorquals
Humpbacks hail from the family of whales called “rorquals,” which includes the fin whale, the sei whale, and the blue whale, the world’s largest animal. Blue whales can grow to 100 feet (30 meters) and weigh up to 330,000 pounds (150 metric tons), bigger than any dinosaur we’ve yet discovered.At 45 feet (14 meters) and 80,000 pounds (36 metric tons), humpbacks aren’t nearly as big as cousin Blue. But they can really sing. In fact, according to a 2006 study, humpback whales sing grammatically, combining sounds into phrases, and phrases into songs, according to complex rules called a “hierarchical syntax.” It’s similar to our ability to combine words into clauses and clauses into sentences.
Humpbacks can dance, too. They are among the most acrobatic of whales, sometimes leaping entirely out of the water. Such breaching is common among males during mating season, when humpbacks migrate from polar feeding grounds to tropical breeding grounds. It’s also during mating season that humpback males sing their syntactically sophisticated songs, presumably in pursuit of humpback gals. Until recently, breaching had only been observed in the breeding grounds. Recent whale studies though have found humpbacks breaching in the ice littoral areas on the edge of the polar regions. That’s the edge of the pack ice which in the spring becomes a morass of small bergs and chunks of ice. Humpbacks have been observed breaching right next to smaller pieces of the flow, and sometimes even striking the edge of them without apparent injury. Needless to say, 36 tons of flying whale hitting a bit of ice sheet sends the ice tumbling. Humpbacks are also known to “hover” by resting vertically at the surface with their heads protruding from the water. It is thought that this lets the humpbacks have a look around above the water. Breaching may let them see even further, possibly in an attempt to spot schools of fish feeding at the surface nearby. This is a very hotly debated subject amongst whale researchers.
Straining for Snacks
Like all rorquals, humpbacks are baleen whales. They feed by taking huge mouthfuls of seawater--literally tons of it--then forcing the water out between hundreds of plates of baleen (a.k.a. “whalebone") that hang from the roofs of their mouths. The baleen plates work like a sieve, letting water out but keeping krill and other munchable marine life in.
To catch that seafood dinner, humpbacks sometimes use a special technique called “bubblenet.” First, one or more humpbacks swim in a circle beneath a school of fish, blowing bubbles that float up to form a wall around their prey. Then the humpbacks swim up through their “bubblenet,” slurping the fish-filled water as they go. Bubblenetting is a typical humpback feeding behavior. In the polar regions a pod of whales will often bubblenet around smaller pieces of loose pack ice. The very warm airbubbles are thought to confuse and dislodge small fish and other creatures that use the ice as cover.
Lunge feeding
Humpback whales have yet another ingenious way of getting thier dinner called lunge feeding. Instead of slowly trawling along processing thousands of gallons of seawater for the occassional shrimp, humpbacks also engage in this type of nearly hunting behavior. Whether alone or in pods, whether used with a bubblenet or not, tropical or polar, sometimes humpbacks will dive deep, turn around, and race towards the surface. As they get there they open their mouths wide and snap up whatever they find. Whale research scientists are very impressed with lunge feeding. “There are some fish that live near the surface. If the whales were to come up behind them the fish would sense it and dart away. It’s like trout and mayflies, only much much larger. Lunge feeding lets the whale catch much bigger creatures we ever realized, especially when they are in a pod in the arctic and making bubblnets. The old idea of the giant gentle humpback getting by on enormous amounts of plankton may just have to be tossed overboard.”
It’s clever, and tremendously effective. A humpback whale can catch, and eat, as much as 3,000 pounds (1,360 kg) of food in a day. But that’s not too surprising--coming from a creature smart enough to sing in syntax. Every year brings exciting new discoveries in the field of whale science. Subscribe to Knowledge News today so you can stay informed!
UPDATE !! Breaking News: researchers find the humpback’s secret protien source.
and are unable to make a statement at this time.
Gotcha!
I had to make up almost a quarter of the above article to do the set up for this pic. Yes, I am that desperate to make teh funny sometimes.
Thank you George and Gracie!
Posted by Macker
05/26/2008 at 06:51 AM
And I thought the humpbacks were making a comeback due to Al Gore’s company and Senator Obama’s candidacy?
We all know if Senator McCain wins, the humpbacks will all commit suicide, right?
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