Dolphin Fleet Naturalist Notebook 31 May to 6 June
May 31 was gray and chilly, but that didn’t stop intrepid whale watchers from venturing off from McMillan Pier in Provincetown to Stellwagen Bank, a National Marine Sanctuary six miles north of Provincetown. On our way to the southwest corner of the bank, we caught a quick glimpse of a large fin whale gliding through the water. Fin whales, the second largest animal on the planet, can be seen in the waters surrounding Cape Cod all year round. Despite their ubiquity in near-shore waters, their speed and elusive behaviors have kept them shrouded in mystery. For more information on fin whale sightings in 2008, see naturalist John Conlon’s latest blog post on the naturalist notebook website.
As we approached Stellwagen Bank, the winds increased and the seas became rougher, but our travels paid off. Passengers were delighted to find a group of four whales, made up of two mother and calf pairs. One of the mothers was a female humpback named Ursa. Ursa is female humpback first seen in 1984. This is her fifth calf.
Because humpback calves are still in their first months of life, they are still feeding on their mothers’ milk. Mother humpbacks, however, spend much of the summer trying to replenish their blubber layers. During the process of giving birth they might lose up to a third of their body weight. So as the two mothers fed on schools of sand lance, the calves breached repeatedly! Scientists aren’t sure why whales breach, but perhaps in this case, these calves were playing with each other or trying to get their mothers’ attention!
A rain squall mid-day on June 1 gave way to bright, sunny conditions for the afternoon trip on the Dolphin VIII. Upon arriving in Stellwagen Bank, we noticed that there was still quite a bit of feeding going on. We watched as Compass used her powerful tail to generate splashes on the water’s surface, stunning fish and causing them to group so that she could swallow a mouthful. As if to imitate her, her calf soon began tail breaching, also slamming its tail down on the water’s surface.
Compass’s calf tail breaches
As a multi-use sanctuary, Stellwagen Bank is a busy place in the summertime. National Marine Sanctuaries operate under the philosophy that by keeping resources available to many different interest groups, said parties will work together for the protection of the shared resource. As a result, it is not uncommon to see fishing boats and recreational vessels out among the hundreds of whales that visit the sanctuary to feed during the summer. We can usually count on some of the same whales to return year after year. Compass, for example, has been observed in Stellwagen Bank nearly every year since 1984.
By June 2, the sun had come out and the wind had died down. Whale watchers aboard the Dolphin VIII were treated to a wide range of humpback whale behaviors throughout the day. Once we reached the southwest corner of Stellwagen Bank, we noticed two dorsal fins sticking up from the flat, calm water. Two humpbacks, Gunslinger and Entropy bobbed at the surface, not moving very much, but occaisionally lifting their flukes so that we could identify them based on the pattern on the undersides of their tails.
Heading north, we found ourselves surrounded by at least 8 more humpbacks, including Stub, Buzzard, Shockwave and her calf. Surely though, our most exciting whale of the trip was a humpback named Thread. Thread is a mature male, born in 1984. We watched, enthralled, as he leapt out of the water in a full-spinning head breach! After this, he proceeded to roll around on his back, giving us a glimpse of the rorquals on the underside of his body. Rorquals are a series of folds or pleats that line the underside of some whales’ bodies. Normally, these folds lie flat; however, when a whale engulfs a mouthful of food and water, these pleats expand, allowing the whale to take in a mouthful of over 100 gallons! The musculature of these ventral pleats also helps to push the salt water out between the baleen plates. Humpbacks are not the only rorqual whales we see around Cape Cod. The fin and Minke whales are also rorqual whales.
June 3 was another spectacular day for humpback mother and calf sightings. In the morning, one of these calves was rolling around, slapping his flipper on the surface, and generally making a commotion as its mother swam below the surface. Time flew by as we watched this young whale, and after a while, we decided to head for home. On the way back to Provincetown, however, something very exciting happened. As we we passed a mother and calf pair, not intending to stop, these two animals simultaneously breached. This was just another example of how unexpected things can happen at any point during our trips!
In the afternoon, passengers on the Dolphin VIII saw Scylla for the first time this season, and the naturalist was excited to note that she was back with a calf. Like her mother, Istar, Scylla is a very productive female. Of all the whales in our catalog, Istar ties for the most calves. She has had 11 that we know of! Scylla is not far behind–she is back this year with her 10th!
Scylla and calf
On the morning of June 4, we saw a mother and calf humpback of particular interest. Tong’s latest calf was recently involved in an incident in which he became entangled in fishing gear. Although the calf was able to free itself of gear, with the help of whale rescuers from the Provincetown Center for Coastal Studies, it is still important to document the animals post-entanglement. Tongs and her calf were with a third whale and appeared to be in good health.
After leaving Tongs and her calf behind, we soon came accross another trio of whales, including a humpback named Tunguska. Tunguska is a male born in 1997. He was named for the marks on his lower left fluke which look like downed trees. This is in reference to the comet “Tunguska” which hit the earth in 1908.
On June 5, high winds, rough seas, and fog made spotting whales quite a challenge. Although the hard-working crew on the Dolphin VII was able to locate one humpback in the fog, the conditions did not merit good looks for very long.
By June 6, the winds had died down and only a rolling swell reminded us of yesterday’s conditions. Although it was raining, we could see for several miles, and this allowed us to scan the horizon for tell tale signs of cetacean life. The morning trip on the Dolphin VII witnessed some of the most exciting whale behavior, as Tulip, Venom, Rocker, and Zeppelin were feeding together along the southern edge of Stellwagen Bank.
After fasting for much of the winter, these whales will feed opportunistically in the rich feeding grounds of the North Atlantic during the summer. On this particular day, these humpbacks were blowing large rings of bubbles in order to scare and capture schools of fish. Humpback whales are thought to do this cooperatively at times, however some scientists believe that sometimes a humbpack will exploit the work of another humpback in order to feed itself! In the photo below, notice the water pouring from the whale’s mouth. It is draining the salt water from its mouth so that it can eat the fish it has trapped in its mouth.
It was another exciting week on the Dolphin Fleet. New calves were documented and stunning surface behaviors continued to delight passengers. We’re excited to see what the first few weeks of summer will bring!