Humpback Humpback
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Journey North Information About
Humpback Whales

Ecology

How much food does a whale eat in one day?
A humpback whale may eat up to a ton of food a day in its feeding grounds (2,000 pounds of sand lance in the Gulf of Maine or a similar amount of krill in more northern waters). The right whale may be eating about 2,625 pounds of copepods a day when it's in Cape Cod Bay or another feeding ground.
What do humpbacks eat when they come up to Stellwagen Bank and the Gulf of Maine?
When they are up north at Stellwagen Bank, which has a nice sandy surface, they are feeding primarily on sand lance -- a small bait fish which is also called the sand eel. Obviously, by its name, the fish likes sandy habitats where it digs itself into the sediments to hide. The fish is about 5-6 inches long and pencil thin. Out of the sand, these fish often crowd into large schools or "balls," making feeding quite efficient for the humpback whales.
Elsewhere in the Gulf of Maine, where sandy bottoms are not as prevalent, humpbacks may be feeding on herring, mackerel, and other small fish, as well as krill and squid. If these prey items are on Stellwagen, the whales will eat them too.
What do the humpbacks eat down in the Caribbean?
Down in the Caribbean the whales are not eating. They live off their reserves of fat called blubber. The mothers spend their time nursing their young, while the other adults are busy mating. The warm waters of the Caribbean are not as productive as northern waters (less phytoplankton, less zooplankton, less fish). That's why they are so clear and the northern waters so murky. The whales usually feed enough in the northern waters to last them through their winter's fast.
Why don't humpback whales eat during the winter in Caribbean waters?
Caribbean waters are so nice for photography because they are so clear. But that clarity also indicates that the waters are less rich in nutrients, phytoplankton and zooplankton. This reduction in small life forms also leads to fewer fish in the food chain. There may be great diversity of life in tropical waters, but you don't see the immense schools of fish that can be found farther north. Humpback whales go to the warmer southern waters to calve and breed, but they don't go there to feed. They gorge themselves on schools of sand lance, herring and other small fish (and krill in other northern waters) when they come up north in the summer.
What makes the Stellwagen Bank Marine Sanctuary a good place for whales to go?
The answer is upwelling -- a movement of deep, nutrient rich water to the surface. In a global picture, most upwelling takes place along the western edge of continents. Winds cause surface waters to move offshore, allowing deep water to flow upwards to take its place. Stellwagen Bank is one such example of an upwelling. When underwater currents encounter an obstruction, the water has to flow somewhere (it cannot be compressed). The only place for this mass of water to go is up. As the rich water settles on top of the bank it provides the nutrients needed by the base of the food chain. Upwelling areas around the world are rich in marine life and are usually important feeding grounds for whales.
What is "upwelling" and how does upwelling affect the ocean food chains?
Upwelling is the movement of deep cold ocean water to the surface. It brings nutrient rich waters to surface. It effects food chains by bringing more food to the surface so organisms in that area have more food. Plants using these nutrients will grow, the herbivore has food, and the small and large carnivores also will eat.
How does the food chain work in the ocean?
In the ocean, animals live and die. Their waste products and bodies (after they die) sink to the ocean floor, there they are decomposed by bacteria and transformed into basic nutrients, such as phosphates and nitrates. These materials are needed by photosynthetic organisms (plants, protists and some bacteria) for growth. In turn, small floating animals called zooplankton eat the phytoplankton. Zooplankton are eaten by small fish, jellyfish, filter-feeding crustaceans and mollusks and many other creatures (including some whales like the right whale), these small animals are eaten by larger animals (including some whales like humpbacks), and large fish are eaten by sharks and orcas.


Where do the humpbacks go during the winter?
The whales we see at Stellwagen Bank are presently down in the Caribbean, around Silver Bank, for their winter calving and breeding season. Although they are most concentrated at Silver Bank, and Navidad Bank close by, humpbacks can also be found from the Bahamas to the Grenadines.
Why would some whales stay and why do others head down to the Caribbean?
It seems that most of the whales do head down to the Caribbean, but in past years not all of the whales made the trip. It is believed that some of the juvenile whales, that may not yet be interested or capable of breeding, may stay to feed in areas where prey is still plentiful. Over the past few years, young humpbacks were seen off the Virginia coast during the winter -- probably feeding on small fish.
Different groups of humpbacks migrate north in a certain order. Which ones migrate first and why?
Whale researchers believe that the first group of whales to head north is the group of pregnant females and resting females who have had calves in the previous year. Why would these be first? It is thought that it is because they can get to the feeding grounds to start building up blubber reserves and to provide nutrition to the growing fetus. The resting females would be recovering strength from the rigors of birthing and nursing. The second wave of whales is usually juveniles those who are not concerned with mating yet so they wouldn't have to stick around down south, and they are still undergoing fast growth. These juveniles would be followed by adult males and females who stayed behind in the Caribbean as long as possible in order to mate. The last group to head to northern waters are the mothers and calves. The calves stayed back to build up their strength (through nursing on their mother's rich milk).
Why do you suppose the young humpbacks remained off the Virginia coast rather than migrate?
Researchers believe that if large amounts of prey are available, young whales may find the food more irresistible than the urge to migrate -- since there's not much for them to do in the breeding grounds.
Where do the Caribbean whales go when they leave the Caribbean?
The whales in the Caribbean come from the Western North Atlantic stock of humpbacks. When they head north, these whales separate out into five herds that swim to specific feeding grounds: 1) Gulf of Maine (including Stellwagen Bank)/Scotian Shelf; 2) Gulf of St. Lawrence; 3) Newfoundland/Labrador; 4) southwestern Greenland; and 5) Iceland-Denmark Strait. Individual whales usually return to the same regions every summer, with mothers bringing their babies with them to join the feeding herd.
What about the humpbacks in the Southern Pacific?
In the Southern Atlantic whales migrate to and from the coasts of Brazil and the mid-African coast to the Southern Ocean.
Are there any humpbacks in the Pacific Ocean?
In the Pacific there are several stocks. The Eastern North Pacific stock feeds along the coasts of British Columbia, Washington, Oregon and California (in all of the west coast National Marine Sanctuaries including Olympic Coast, Cordell Bank, Gulf of the Farallones, Monterey Bay and Channel Islands). These whales travel down to central Mexico, Baja California and even Central America (see last week's report) for calving.
Aren't there whales around the Hawaiian Islands?
Another group of North Pacific whales uses the quiet, warm waters around the Hawaiian Islands for calving (another National Marine Sanctuary). These whales travel to southeastern Alaska (although they can occasionally be found off the coast of British Columbia).
Are there humpbacks in the Southern Pacific?
In the southern Pacific there is an Antarctic stock which feeds in the Southern Ocean during their summer and calves in the waters around Australia and New Zealand in the winter. Another stock can be found just east of the Australian whales. They too feed in the Southern Ocean and have been found in much of the South Pacific, including American Samoa (site of another National Marine Sanctuary). Whalewatching (particularly through nature tours of the Galapagos Islands) has also caught on along the Pacific Coast of South America. Whales calve in the warm tropical and subtropical waters and move south to the temperate and polar waters to feed.


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