A whale of a tail
The migrations of the humpback whales that swim between the Caribbean and north Atlantic each year is one of the great mysteries of the ocean – but one that YOU can help solve. Nathalie Ward reveals how sharing your photos of whales can help researchers understand humpback behaviour
The size of a city bus, Salt rises from the sea, firing vaporous plumes from her blowholes, then slowly rolls into the depths, exposing a tiny, salt-sprinkled dorsal fin. As she dives, she raises her 4.5m-wide tail flukes over the water, like the outstretched wings of a massive seabird.
Salt is one of the most distinguished and photographed humpback whales in the world. A prolific mother, her impressive family tree includes 31 known children, grandchildren and great-grandchildren. Indeed, she was the first humpback whale to have been given a name. Humpbacks’ names are usually based on the unique natural markings on the underside of their tails – but Salt’s was inspired by the thick white scarring on her dorsal fin that looks as if someone sprinkled salt on it.
Her name isn’t the only thing special about Salt. This 13m-long, 40-ton matriarch was first seen in 1975 off Cape Cod in Massachusetts, on the north-eastern coast of the USA; she was re-sighted on Silver Bank off the Dominican Republic in 1979, confirming her north–south migration between the North Atlantic cold-water feeding grounds in Stellwagen Bank National Marine Sanctuary on the Gulf of Maine, and her warm-water breeding grounds in the Caribbean.
Salt is one of only a few Gulf of Maine whales to have been seen by researchers in the Antilles in three separate years, though she probably comes here every winter. Her son Crystal and grand-calf Etch-a-Sketch have also been seen by researchers in the West Indies.
By watching Salt and her offspring, scientists have learned a lot about humpbacks. We’ve discovered that humpback mothers give birth to a single calf every few years. Those young whales are born tail first, weigh about 1½ tons and are a whopping 3m-4.5m long. Newborns drink an amazing 450 litres of fat-rich milk (the consistency of cottage cheese) each day, growing as much as 1.25cm per day during the first six months of life.
Each calf stays with its mother for up to a year before it is weaned off its mother’s milk and onto a solid diet of fish. Once on its own, this young animal will return each year to the feeding area it first experienced in its youth.
Though we do not know Salt’s exact age because we never saw her as a calf, we know a lot about her because of the 40 years of observation data collected aboard whalewatching vessels. And though we still have many unanswered questions about the culture and life history of humpback whales, Salt has certainly been a great teacher.
It’s not just for fun that humpback whales are named for the distinctive pigmentation patterns on their flukes – flukeprints, the ‘fingerprints’ of whale identification. The goal is to match name with patterns so that they are easily recalled by researchers in the field – naming each whale helps us communicate about them across the wide range of the population, and helps the whalewatching public to connect to these interesting animals as individuals with unique histories. Today, more than 2,200 humpback whales have been named and are tracked by scientists as they travel from the Caribbean to their summer feeding grounds in the north Atlantic.
When humpbacks dive, they often raise their flukes above the water and provide the opportunity to photograph the markings on the underside. Natural markings captured this way have allowed researchers to monitor the movements, health and behaviour of individual humpbacks since the 1970s.
This photo-identification technique enables scientists to identify an individual whale anywhere it may travel throughout its life by comparing scars and markings on the flukes; these pigmentation patterns are used to create catalogues of known individuals and their movements. Scientists have thus gathered valuable information about population sizes and migration patterns.
You can help with this research. In 2014 an internet-based system, CARIB Tails, was launched to enlist the Caribbean yachting/boating community as citizen scientists to take on a special role to help protect their fellow travellers. All you need is a camera and knowledge of safe boating around whales.
How can you get involved? When you spot a humpback whale from a yacht or ship, simply take photographs of the distinct patterns on its tail, and email the photo along with details of your location – you’re a citizen scientist! This information can help researchers track the movements of these whales between their five North Atlantic feeding grounds in the USA, Canada, Greenland, Iceland and Norway and their West Indies breeding ground. The information is analysed and catalogued by Allied Whale (Bar Harbor, Maine) to help researchers monitor humpback recovery. While thousands of fluke photographs from northern feeding grounds, like Stellwagen Bank Sanctuary, fill the North Atlantic Humpback Whale Catalogue, so far very limited information exists from the remote and under-surveyed areas of the Eastern Caribbean islands. Your help is needed!
Thanks to CARIB Tails citizen scientists and sister sanctuary research partners, we’re already learning new details about the timing and movement patterns of humpback whales from the south-eastern Caribbean. For example, new data suggest that the West Indies humpback whales comprise more than one breeding population, contrary to our previous understanding.
How to get involved…
For more information about how you can participate and learn more about CARIB Tails and its Sister Sanctuary Program, Protection Beyond Borders, visit: www.caribtails.org, where you’ll find details of how to send your photos of whale flukes to the researchers and add to our knowledge of these amazing creatures.
You can also learn about marine mammal protection in the Caribbean under the framework of the United Nations Environment Programme’s (UNEP) Specially Protected Areas and Wildlife (SPAW) Programme: http://www.cep.unep.org/cartagena-convention/spaw-protocol/overview-of-the-spaw-protocol
Where to watch whales
Humpbacks migrate off Dominica’s leeward coast between January and March, but other cetaceans – including sperm whales, short-fin pilot whales and dolphins – can also be spotted.
Rincón on the west coast is well placed for spotting humpback whales between January and March.
Several thousand humpbacks arrive off the north-east coast between January and April, drawn to the breeding and calving grounds of Silver Bank, Navidad Bank and Samaná Bay in the 36,000-sq-km Marine Mammal Sanctuary of the Dominican Republic.
Guadeloupe & Martinique
Migrating humpbacks can be spotted in Grenadian waters, along with orca, Bryde’s, sei and sperm whales, plus a dozen other species. January to March is peak season.
St Lucia, St Vincent & the Grenadines
Humpbacks may be sighted between January and April, along with Bryde’s whales and orcas, plus sperm and short-finned pilot whales.
US Virgin Islands, British Virgin Islands and St Kitts & Nevis
Humpbacks pass through the waters of these islands during their annual migration between the Caribbean and the north Atlantic.