top of page
  • Writer's pictureDebbie Hatch

Eye to Eye with the Sperm Whales of Dominica

Sperm Whale in Dominica

Earlier this week, two members of our Board had the amazing opportunity to snorkel with the Sperm Whales of Dominica. The island's sheer underwater drop-offs create deep sheltered bays along its western coastline–the perfect haven for the Sperm Whale to breed and calve. Dominica is the only country in the world where Sperm Whales reside year round and the waters surrounding this island are home to about 200 resident whales. In fact, nearly 800 square kilometres of royal blue waters of this island nation that serve as key nursing and feeding grounds have been designated as a reserve, “We want to ensure these majestic and highly intelligent animals are safe from harm and continue keeping our waters and our climate healthy,” Dominica Prime Minister Roosevelt Skerrit said in a statement.

First, please note that the only legal way to have in water encounters with these whales, is to be on a government issued permit.  Both the number of boats and the number of people allowed in the water are very limited and we absolutely support those restrictions. Our boat captain, the four swimmers and one crew member on our boat were all very respectful. We did not touch, chase, or harass the whales. We were on a permit. We slipped into the water and let them come to us. It was an amazing experience.

A few things that we learned about Sperm Whales:

Sperm Whales are the largest of the toothed whales and can grow up to 60 feet long. Found in all deep oceans, from the equator to the edge of the pack ice in both poles, they have one of the widest global distributions of any marine mammal species. Sperm whales have conical teeth on their long, narrow, lower jaw. The teeth fit neatly into sockets in the upper jaw, which has no teeth. This arrangement is a perfect adaptation for slurping up soft-bodied squids.

Sperm Whales are named after the waxy substance - spermaceti - found in their heads. The spermaceti is an oil sac that helps the whales focus sound. It's also the reason these whales were a primary target of the commercial whaling industry from 1800 - 1987. According to Smithsonian Magazine, "by 1958 more than 20,000 Sperm whales were killed each year to be turned into margarine, cattle fodder, dog food, vitamin supplements, glue, leather preservatives, candles, fine soaps, cosmetics and brake fluid." Populations declined so drastically that in 1986 the International Whaling Commission issued a moratorium on commercial whaling. In the pre-whaling days, an estimated two million Sperm Whales roamed the Earth’s deep waters. It's estimated that about 800,000 remain.

Speaking of their heads, Sperm Whales have the largest brain of any other animal on earth! Even after decades of study, basic elements of Sperm Whale biology and behavior are poorly understood. We do know the whales can stay underwater for up to two hours but 20 - 45 minutes is more typical. Sperm Whales produce a series of clicks called codas. Each whale has a distinctive coda and scientists think that Sperm Whales recognized each other by these clicks. The Marine Mammal Center Organization notes there is also evidence that Sperm Whales may also produce intense bursts of sound to stun their prey. .

Female Sperm Whales reach sexual maturity around 9 years of age when they are roughly 29 feet long. At this point, growth slows. Females reach their maximum length and are physically mature around 30 years old at which time they measure up to 35 feet long. Puberty in males is prolonged, and may last between ages 10 and 20; they often do not actively participate in breeding until their late twenties. For the first 10 years males are only slightly larger than females, but males continue to exhibit substantial growth until they are well into their 30s. Males reach physical maturity around 50 years. At that time they are approximately 52 feet long.

Mating occurs in spring and summer. Females carry their young 14-16 months, giving birth

Sperm Whale in Dominica

to a single calf measuring about 13 feet long (and weighing one ton), every three to five years. These calves nurse for two years but may continue nursing intermittently for up to eight. Females and young males are social with each other and are sometimes seen in matriarchal pods of up to 50 whales but, on average, 12 females and their young will form a social unit. The young males will leave when they are between 10 and 21 years old and can be found in "bachelor herds" until they are able to compete in mating at about 20 years old. Aside from breeding season, adult males lead a solitary life.

Then there is this amazing fact: Sperm Whales defecate near the surface because they shut down non-vital functions when they dive to depths of up to 3,000 meters. As a result, nutrient-rich poop remains along the ocean surface and creates plankton blooms, which capture CO2 in the atmosphere and drag it to the ocean floor when they die. Did you know that whale poop is a natural carbon sink?

I want to reiterate that all of my photographs/videos were taken while under government permit.

81 views0 comments


bottom of page