Humpback Whale Calves
Humpback whales become reproductively mature when they are between five and eight years of age. They mate during their winter migration to Hawaii, and eleven to twelve months later, upon their return to winter breeding grounds, the mother gives birth to a single calf. A fifty foot mother will give birth to a calf approximately fifteen feet long and weighing around two tons. The newborn instinctively swims to the surface within 10 seconds for its first breath. The mother begins feeding her newborn about 100 pounds of milk each day for a period of around six months, then the calf is sustained through a mixture of nursing and independent feeding for six months more. The mother’s milk is pink in color and exceptionally high in fat content (50%) which allows the calves to gain weight quickly. It is imperative for them to develop a thick layer of blubber prior to their 3,000-mile migration back to the cold Alaskan waters. After weaning, the calf has doubled its length and has increased its weight five times, attaining a size of about thirty feet and ten tons.
In Hawaii, humpback whales typically belong to groups consisting of two to three individuals for relatively short periods of time. The longest association between individual whales is when the mother cow, remains with her calf for a year during nursing. The mother generally never lets her calf stray more than a body length away for very long. They spend the first year or so of the calf’s life together, and the calf learns valuable survival lessons in this short amount of time, and is then weaned and separated. In many instances, cow and calf are accompanied by another adult known as an escort. Escorts can be of either sex, but are most often reported to be males, and remain with them for only a short time. Usually, a female humpback will bear one calf every two or three years, with an average life span between 40 and 50 years.
Humpback Whales Healthy In Hawaii
Humpback Whales are increasing their numbers in Hawaii by a healthy 6 to 7 percent each year. Humpback whales of the Northern Pacific Ocean undertake a great migration from Alaska covering about 3500 miles one way. Considered an endangered species, the Humpbacks are doing well in Hawai’i's protected waters. Now numbering about 10,000, they will mate, calve, and nurse their young in Hawaii before returning.
One way to study the population size of the humpback whales is the Hawaiian Islands Humpback Whale National Marine Sanctuary’s annual whale count, where hundreds of volunteers go to 60 sites on the last Saturdays of January, February, and March to count whales. More than 800 volunteers showed up in January and counted whales from the shores of Oahu, Kauai, and the Big Island, with some seeing as many as 6 whales within a 15-minute interval. Here are the average numbers of whales sighted per 15-minute count period on each island:
O’ahu – 3 whales
Kaua’i – 2 whales
Big Island – 6 whales
Again on the last Saturday in February and March, volunteers will fan out along the shores of O’ahu, Hawai’i and Kaua’i for the sanctuary’s annual whale count. The count provides key population and distribution information on humpback whales around the Hawaiian Islands. The Pacific Whale Foundation will conduct its own whale count on Maui. If you would like to volunteer and be a part of this success story see Humpback Whale Ocean Count 2010.
Humpback Whale Rescue
Marine experts from the Hawaiian Islands Humpback Whale National Marine Sanctuary freed a yearling humpback whale that had been entangled in heavy plastic rope. Presumably the whale became tangled in the line several months ago in its winter feeding grounds off Alaska and towed it all the way to Hawaii. The rescue effort lasted for five days when the whale was first spotted caught up in 400 to 500 feet of rope which ran through the whale’s mouth, around its head and twisted into a knot.
Several attempts were made over several days each with its own challenges and degrees of success. Complicating the task was the fact that the juvenile’s mother and her male escort have been sandwiching the young whale by swimming on either side of it. Another difficulty is that the whale’s mouth is normally submerged unless it’s coming up for air for only a second or two. The rescuers have been able to follow the whale’s whereabouts using a tracking device that they attached to the rope.
When the whale was spotted on day five, experts began a five-hour effort to free the whale using a technique modified from one that whalers used to kill the animals a century ago. They attached three plastic air-filled buoys to the rope on the whale, trying to slow the mammal. Even while pulling the buoys, the 30 foot calf still traveled at 5 knots, making it difficult to cut the rope in heavy seas.
The crew then attached a sea anchor, a device like an underwater parachute, and the whale finally slowed and began staying near the surface. They hooked a knife to the rope near the whale’s back using a long pole, needling the blade between the rope and a cleft left by a wound from the rope. The knife was then attached to another sea anchor, and after 10 minutes it sliced through the rope.
The animal has abrasions and a partially healed wound behind its blow hole, probably caused by the rubbing of a knot in the rope, but now “It’s in good shape.” The rescuers freed the calf without separating it from its mother and a male escort, and all three swam off.
Humpback Whales Hawaii
Humpback whales, being mammals just like humans, exhibit a number of traits common to all mammals including the following: they are warm blooded, breathe air, and bear live young and nurse them with milk. Adults typically range in size from 35 to 55 feet, and weigh approximately 80,000 pounds. Their scientific name is Megaptera novaeangliae (giant wings of New England) which refers to their large pectoral fins that can reach a length of 15 feet. These fins are used for maneuverability, stabilization, enabling the whale to stop, and swim backwards.
They can easily be identified by their stocky bodies with obvious humps and black dorsal colouring. The head and lower jaw are covered with knobs, which are actually hair follicles and are characteristic of the species. The tail flukes, which are lifted high in some dive sequences, have wavy trailing edges. The long black and white tail fin and the pectoral fins have unique patterns, which make individual whales identifiable.
Humpback whales don’t have teeth, but instead have baleen. The baleen is a wide plate in the whale’s mouth, made up of hundreds of long, fringed blades forming a sieve that the whale uses to filter krill, plankton, and small fish out of seawater. These blades measure 18 to 36 inches. Most baleen whales feed by taking a large mouthful of food and water, trapping the food behind the baleen, and then swishing the water out through their baleen plates.
Humpback whales are found in all of the world’s oceans, although they generally prefer habitats near shore or island for both feeding and breeding. The humpbacks of the North Pacific live in the waters off Alaska in the summer, and migrate each year to the main Hawaiian islands and stay during the winter months of November through May. The round-trip distance they travel during this annual migration is approximately 7,000 miles, one of the longest migration distances of any animal species. During their stay in Hawaii, they do not feed, but devote most of their time to mating and bearing their calves.
Humpback Whale Migration
Humpback whales of the Northern Pacific Ocean undertake a great journey covering about 3500 miles one way. The waters around Alaska provide a bounty of food, while the waters around Hawaii are relatively warm and thus offer ideal conditions for breeding. During the time between the end of October and the beginning of May, the whales diet and a full-grown humpback whale loses several tons of weight during the time it spends around Hawaii. A nursing mother may even lose a third of her weight.
The humpbacks do not all migrate at one time, and some do not migrate. Most of the humpbacks head to Hawaii alone or in a small group, meeting with other whales on the way. Scientists suggest that a collection of humpbacks should be called a group. They have decided that the word ‘pod’ is to be used for structured groupings, such as the families of dolphins, orca, sperm whales, and others.
With the help of transmitters and satellite monitoring systems, scientists have been able to determine the duration of their migration. Humpback Whales (Megaptera novaeangliae) travel at an average speed of approximately 5 miles per hour, but are able to reach up to 15 mph for a short time. Through observations of individual humpback whales, scientists estimate that they travel a distance of approximately 3500 miles between their breeding and feeding grounds in 30 to 40 days. One individual humpback was identified in Alaska one day and in Hawaii only 28 days later, which means that this particular whale traveled 3500 miles in less than a month.
How long they stay in Hawaii waters before heading back to Alaska depends on different circumstances. A recently impregnated female may head back right away (one identified female headed back after just 21 days in Hawaiian waters). A mother who has given birth will stay longer until the calf is strong enough to make the long journey.
