October 28, 2016
Humpback Whales: A Comeback Story in the Salish Sea and Beyond
While May through September tends to be peak season for spotting killer whales, also known as orcas, here in the San Juan Islands, we are in the midst of a second peak in whale sightings right now. From about September into November we have our peak sightings of humpback whales. These past weeks have been just spectacular for spotting these beautiful creatures.
A Background on the Mighty Humpback
Humpback whales are regarded to be the fourth or fifth largest whales in the world. Here in the North Pacific the individuals in our stock of humpback whales are usually right around 45 feet long and weigh in at right around 90,000 pounds. Overall we are talking about an animal that is about the same length as a school bus and the same weight as seven African elephants! There is slight sexual dimorphism, males usually are a few feet shorter in length and few thousand pounds lighter than females, but it is difficult if not impossible to tell the difference between the sexes from above the surface.
Humpback whales belong to a taxonomic group of whales known as Mysticetes, or baleen whales. This means that instead of possessing teeth, humpbacks have plates of baleen, made out of keratin – the same biotic material that our fingernails and hair are made out of, that they use to filter their food from the water. Humpbacks will take mouthfuls of water around their favorite foods (baitfish, krill and other small organisms about the size of our pinky fingers), press their tongues up against the roofs of their mouths squeezing the water through these baleen plates, leaving a big mouthful of food to swallow back. Per day these massive animals are consuming over a ton of tiny prey items each in their swimming-pool-sized mouths.
Migration to the Calving and Breeding Grounds
Perhaps the most impressive thing about humpback whales is their migration pattern. Here in the North Pacific these whales make an amazing trek from up here in the Salish Sea, British Columbian, and Alaskan waters down mostly to the Hawaiian Islands for their breeding and calving season from December through May. This is a 3,000-mile journey one-way across wide-open water! The fastest recorded migration is though to have taken one whale 33 days once in Hawai’i the whales will form competition pods, consisting of one female surrounded by her male “escorts.” These groups can be as small as one female traveling with a male or as large as 30+ males competing for one female. After much competition, posturing, and jostling between the males that can last for days, the female will select a male with which to breed. The competition pod will dissolve, males going off in search of other females with whom to breed, and females either staying to breed again or heading back north on migration. This process is made more arduous by the fact that the whales only have access to their food while they are at the northern reaches of their range. From the time they leave on their migration, swim to Hawai’i, breed, and swim back North, they are not eating!
On the breeding grounds one of the most fascinating displays in the animal kingdom takes place: singing! These haunting vocalizations occur only on the breeding grounds and are only produced by the males in the population. To make this behavior even more impressive every single male on the breeding grounds is singing the same song that changes slightly every year. For a long time scientists though these vocalizations were produced to attract females, but it was recently shown that when singing the males are actually attracting other males! These groups of males will then infiltrate competition pods, much like a group of wing-men following around one of their friends in a bar.
Birth of a Baby Humpback
After breeding in Hawai’i, female humpbacks will be pregnant for about 12 months, feeding in nutrient-rich waters here in Northern latitudes, before heading back 3,000-miles south on migration to Hawai’i. Upon reaching Hawai’i these pregnant females give birth to a 15 foot-long, 1,500-pound, pick-up truck sized calf in the protected and relatively predator-free warm waters surrounding the islands. Since whales are mammals, she will produce a fat-rich milk to feed the baby. Drinking that milk the calf will gain about five pounds an hour for a total of just over 100 pounds gained per day! Mom and baby will stay in Hawai’ian waters for about two to three weeks before heading out for the last leg of the migration, another 3,000-mile journey north. Remember that this mother humpback whale will not have eaten since leaving our beautiful northern waters. By the time she makes it back to these feeding grounds after swimming a total of 6,000 miles, giving birth, nursing her calf, and protecting the baby from potential predation, she will have lost up to a third of her body weight totaling upwards of 30,000 pounds! The relationship between mother and calf lasts for about a year, at which point the babies are weaned and start traveling independently from their mothers. Females can produce a calf every year, but typically females will take a year or two off between calves.
An Incredible Recovery
This ability to produce calves each year, or even every other year, has been instrumental in the recovery of the humpback whales. By 1968 Humpback whales in the North Pacific were considered to be commercially extinct, meaning that the whaling fleet hunting whales could not find enough humpback whales to remain profitable. At that point boats were no longer actively hunting humpback whales Some estimates say that the population of humpbacks in the North Pacific could have been as low as 1,500 to 2,500 individuals at that time. At that point in time we saw several pieces of protective legislation pass here in the United States, including the Marine Mammal Protection Act and the Endangered Species Act (ESA) offering the humpback whales additional protection. In addition to these domestic laws, we had the formation of the International Whaling Commission (IWC), which, given mounting public pressure, passed the International Moratorium on Commercial Whaling. Since that time we have seen a remarkable population rebound from these North Pacific humpbacks, with an estimated current population of about 24,000-26,000 individuals. Here in the United States this population of humpbacks is in the process of being delisted from the Endangered Species Act this year, 2016.
Here in the Salish Sea we have seen this recovery first hand. Humpbacks used to be regular visitors to the San Juan Islands, some suggest that we may have had a resident population of whales that returned to our waters each and every year. At the turn of the century we saw those humpbacks hunted out of the area, and we saw about an 80-100 year absence of humpbacks here in the Salish Sea. The years 2000 and 2002 brought with them the first reliable sightings of a humpback in our waters, an individual identified and designated BCY0324 “Big Mamma” with calves in tow. Since that time we have seen our population of humpback whales explode in the inland waters, with a current estimated population of 75-100 individuals here in the Salish Sea. With the recent growth in this population, especially in the last five to six years, we have come to expect a peak of sightings of humpbacks in the spring and the fall adding to the already impressive diversity of wildlife spotted during those times!