- Research & Education
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Bright, clear skies and glassy calm seas made 21 July a perfect day to be out on the water. In the morning we traveled to the Southwest corner of Stellwagen Bank, which is often a hotbed for feeding humpback whales. The steep, sloping edge of the underwater bank is an ideal place for an upwelling to occur, as currents sweep through the area, hit the wall of the bank, and circulate nutrients from the ocean floor that have accumulated at the base of the bank. As nutrients get circulated, phytoplankton blooms, supporting the entire food web and creating an area of high productivity. Certain species of zooplankton eat the phytoplankton, fish eat the zooplankton, and humpback whales eat the fish in unfathomably large quantities.
Today, we found over 14 humpback whales concentrated in this area, feeding intently all around the boat. Dome, Seal, Trident, and Putter used bubble columns to trap fish and Cardhu, Bolide, and Salt used their powerful tails to kick feed, further stunning the small fish in the area.
By the afternoon and evening trips, feeding was continuing throughout the bank, although Dolphin Fleet boats explored further areas. Even east of the bank, humpback whales were found feeding as late as the 5:30 trip, further demonstrating that these humpbacks will feed wherever and whenever they can.
On Sunday, 22 July, we returned to the Southwest corner of Stellwagen Bank. Though we didn’t have quite the density of humpbacks that we encountered the morning before, we did get a chance to observe different species and individuals in the area. Giraffe and Anchor lunged through clouds of bubbles they had created while Anchor’s calf stayed near the surface, never straying too far from its mother. Anchor’s calf is very small and still nursing, and it will likely not stray more than a few hundred feet from its mother’s side until the end of the year.
Meanwhile, nearby, 3 finbacks were observed. Upon returning to the area later and recognizing these finbacks from the size and shape of their dorsal fins, we realized that they were feeding. Finback whales swim in circles as they feed, although this is not always obvious from a boat. As finback whales often spend less time at the surface than feeding humpback whales, it is sometimes easiest to determine that finbacks are feeding by watching their fluke prints, or surface disturbances on the water left behind by the upstroke of their tails. When we see fluke prints rise to the surface in a curved, parabolic shape, we can be relatively certain that the finback is circling its prey before lunging through it.
By 23 July, the weather had changed dramatically, and we found ourselves facing the challenge of rapidly diminishing visibility. Morning trips enjoyed looks at three different species of baleen whales, including humpbacks, finbacks, and Minkes.
Minke whales are the smallest of the rorqual whales, and likewise also have the shortest baleen plates, some of them reaching lengths no greater than six inches. The term “rorqual whale” refers to the pleats of skin that line the ventral side of the whale’s body which expand as the whale takes in mouthfuls of food. These ventral grooves are a particularly useful adaptation as it allows the whale to maximize the amount of food it takes in with every gulp. The musculature of these grooves also helps the whale push the saltwater out between the baleen plates.
Throughout the day, the density of the fog increased and our visibility decreased to the point where we couldn’t see the bowsprit from the wheelhouse. With such low visibility, we had the unfortunate experience of not seeing any animals during our evening trips! On the Dolphin Fleet, getting “skunked” (the term that whale watchers use for this disappointing experience) only happens less than one percent of the time. Assured that this was an unusual experience, passengers were given a coupon for a free whale watch so that they could experience the wide variety of life in Stellwagen Bank on a future date.
Luckily, by July 24th, the weather had cleared and we were back to our normal state of excellent whale sightings! For the people who came out again after the trip the evening before, it was as if we were visiting a different ocean entirely. In the morning, our captain noted on our depth sounder that there were unusually heavy concentrations of bait fish below the surface. As small schooling fish are the favorite food of humpbacks, finbacks, and Minkes, we suspected that whales would begin to feed in that area very soon.
Our prediction came true in our early afternoon trip. By that time, we didn’t need a depth sounder to see that the water was thick with sand lance, the favorite food of the humpback whale. Because the color and texture of the water had changed so abruptly, it was initially unclear what was causing the aberration. Upon closer examination, however, it was obvious that the tens of thousands of sand lance were causing the rippling effect visible all around the boat. We weren’t the only ones to notice the huge schools of fish, however, and humpbacks had already figured out that this was the perfect place for lunch.
Minke whales were dispersed among the group of 6 humpbacks in the area. A whale named Alphorn joined a group of humpbacks that were collaborating to blow a bubble net, composed of concentric rings of bubble columns. After deciding that we were out of time, we decided to head back to Provincetown, however, as is frequently the case, our trip did not stop then. On our way back to the dock, we passed three more humpbacks, including a calf, as well as a large group of finback whales, which also included a calf!
This exciting feeding behavior continued through the next day, July 25th. Dolphin Fleet whale watch naturalist and resident bird expert Peter Trull wrote of his morning trip on the Dolphin VII,
“Two to four miles North of the Ranger Station [near Race Point Beach] we encountered feeding whales, terns, laughing gulls, sooty and greater shearwaters. Every aspect of feeding behavior was represented. We watched humpback whales kick-feeding, blowing bubble clouds and bubble columns. Thousands of sand eels jumped straight out of the emerald green water as open-mouthed humpbacks and 80-100 common terns grabbed fish. Twenty-five to thirty humpbacks, four to six finbacks and two to four Minke whales were observed. Fin whales were lunge feeding amongst the humpbacks while Minke whales zipped by.”
As anyone who has ever seen feeding humpback whales can attest, birds, as well as whales, are an important component to the ecosystem in Stellwagen Bank. Frequently, birds are seen in association with feeding whales, often landing on their heads or backs, trying to take advantage of any fish that the whales leave behind after forming a bubble cloud. Sometimes observers looking for whales will scan the horizon for large groups of agitated birds, as this is frequently an indicator of whale feeding as well!
Also spotted on Wednesday’s trip were Tulip and her calf. Tulip has displayed the typical reproductive interval of a healthy female humpback, as her last calf was born in 2005.
Tulip and calf
By the morning of July 26th, after two straight days of intense feeding, many of the
whales we had seen as very active in previous days seemed to be taking a break from all the activity. Pepper and her calf were traveling slowly in a linear direction, while other humpbacks, including Reaper and her calf, were observed logging at the surface. We were also relieved to see a humpback named Springboard, observed last week with squid gear attached to its body, apparently entanglement-free.
Because whales are voluntary breathers, they can’t sleep in the same way that humans do, as a complete loss of consciousness would mean that they would forget to breathe. Logging is a behavior that seems to be a humpback whale’s equivalent of sleep. As humpback whales are buoyant, they can float at the surface and breathe every so often without expending too much energy. For whales that are negatively buoyant, such as finback whales, the possibility of real sleep is even less likely. As dolphins in captivity are known to sleep with half their brains at a time, it is thought that this might also translate to resting behavior in larger, less buoyant cetaceans like finback whales.
By the evening’s trip, the lethargic whales of the morning had become more active and Dolphin Fleet whale watching passengers experienced a wide variety of active whale behavior. One boat happened across Sickle and her calf. Sickle breached as her calf lolled around on its back, slapping its flipper on the surface.
Later in the evening, passengers on the Dolphin VIII were treated to a rare sight—four different mother and calf pairs feeding and playing together! While Pepper, Black Hole, Perseid, and Reaper kick fed and lunged through schools of fish, their calves, displayed a wide array of active surface behaviors that most people would interpret as play. Pepper’s calf lobtailed as Perseid’s calf breached repeatedly. This group was not exclusive to mother and calf pairs, however, and Calderas, another large humpback was not to be missed blowing bubble nets and engulfing huge mouthfuls of food!
June 27th was hazy and sultry and most people found the pleasant breeze on the boat quite refreshing. Gulls and shearwaters swooped down and grabbed fish from the water near circling finback whales. Meanwhile, in the distance, white water was observed. Rune and her calf were breaching repeatedly, and Dolphin Fleet passengers were awed by the sight of a young humpback throwing itself out of the water and landing on its back, generating an enormous splash! Rapier and her 2006 calf were observed traveling and fluking together.
Rapier and her 2006 calf
This week was also notable for its thick and rich plankton samples taken during several of the week’s trips—no surprise considering the massive amount of feeding that went on during the week. Even though baleen whales in Stellwagen Bank feed mainly on small fish, these fish need to eat too, and our plankton samples often reveal their food. Among the usual abundance of copepods we also found a few pieces of krill, lobster larvae, and even comb jellies. Comb jellies are reminiscent of jelly fish in appearance, but are not truly jellyfish as they don’t have tentacles and don’t sting. Instead, the cilia lining their bodies help to propel them through the water. Comb jellies or ctenophores eat other small types of zooplankton, such as copepods and other crustaceans, and are occasionally preyed upon by cod, among other larger fish.
Such plankton samples remind us of why we are often afforded the opportunity to see so many whales as part of a complex and productive ecosystem.
Another mother and calf pair sighting left us with a lovely close to a week of excellent whale watching. Notice how Reflection is lying on her side while her calf floats at the surface just a few feet behind her!
Reflection and her calf