Orcas
A submerged orca swims past onboard a Discovery Voyages custom small ship cruise in Prince William Sound, Alaska. Photo by Hugh Rose
Compiled by Captain Rand, Discovery Voyages, Prince William Sound, Alaska
Killer whales (Orcinus orca), are known by many names: most commonly “orcas,” but also called “whale killers” (as they were known by whaling men of days gone by) and sometimes as “wolves of the sea,” both because they travel and hunt in packs as wolves do, and because they are connected in Yupik mythology. Killer whales are actually not whales, but the largest member of the dolphin family. Easily identified by their black and white coloring and distinct triangular dorsal fin, they are found in all the world’s oceans, from the Arctic and Antarctic to the warm tropical seas - and frequently on our tours on Prince William Sound.
Geographic Range and Population
Very rough estimates of total world population place orca numbers at 100,000. Most of these are in the Antarctic, with the rest spread thinly throughout the tropical pacific, the North Pacific and off the coasts of Japan and Norway.
Physical Characteristics and Diet
Full-grown female Orcas range from 16-23 feet in length and often weigh over 3 tons. Males are 19-26 feet in length, and weigh in excess of 6 tons. These animals have a lifespan of up to 80 years that somewhat resembles the life cycle of humans. They are sexually mature at 15 years of age (although they have a gestation period longer than that of humans at 15 to 18 months) with females able to breed until about 40 years of age. Males are also sexually mature at 15 years of age but typically do not reproduce until 21. Killer whales have one of the most diverse diets for a cetacean (whale, dolphin or porpoise) —they feed on everything from fish and squid to marine mammals and birds.
Able to propel their stocky bodies at amazing speeds of over 35 mph, orcas are the fastest marine mammals. They also can put on a dazzling show for the passersby by spy-hopping (poking their head above the water to look at their surroundings), breaching (jumping completely out of the water), or flashing their tails when they dive down to feed (though tail-slapping can also be an expression of aggravation).
Vocalization
Orcas are highly vocal and produce a variety of clicks and whistles used for communicating and echolocation (a method of orientation similar to a bat’s radar for locating insects to feed upon). Resident whales seem to be more vocal as they prey mainly on fish, which do not have very good hearing. Transient orcas must be quiet as they pursue their more advanced marine mammal dinners like seals or sea lion pups.
Orcas’ have advanced abilities to not only communicate, but to do so with dialects unique to their pod. Due to this adaptation, they are considered to have cultural faculties with no parallel outside humans.
An orca breaching in Prince William Sound, Alaska on a Discovery Voyages custom small ship cruise. Photo by Patrick J. Endres
Classification and Transiency
Although globally there are up to 5 distinct orca “types” distinguished by geographical range, physical appearance and prey, here in the Prince William Sound region of Alaska there are two distinct groups of orcas, transients and residents, as defined by their social and eating habits.
The nomadic “transient” orcas that frequent the Sound seasonally feed largely on mammals such as seals and young sea lions, while “resident” orcas feed on oily, fatty fish such as sockeye salmon and Pacific herring. Transients are far more elusive and usually travel alone or in small groups, often exhibiting stealth-like hunting behaviors. Residents are social creatures that travel in family pods of 5 to 50—usually led by a female and containing members from newborns to 80-year old members—and can be found in these family groups in their respective “home waters” all along the coast of Alaska and the Pacific Northwest. Transients move from place to place, and appear to range into numerous resident orca areas, but they not intermingle with other groups.
Orcas at Risk in the Wild
Although the orca is not considered to be an internationally endangered species, some local populations are considered threatened or endangered due to the depletion of prey species, habitat loss, pollution by PCBs, capture for marine parks, and conflicts with commercial fisheries.
It has recently been discovered that transient Orcas are highly at risk because of their feeding habits; they have the highest level of man-made pollutants sequestered (stored) in their tissues than any wild animal in the world. This is because of the large amount of unregulated industrial pollutants discharged into the environment globally, which work their way up the food chain, eventually into transient killer whales’ diets. Since they feed higher on the food chain, toxins have had more time to accumulate in their prey, and as killer whales can live many years, they compile large amounts of these toxins over their lifetime.
The 1989 Exxon Valdez oil spill in Prince William Sound caused the death of many orcas. In addition to the loss of local Orcas caused by the spill, the scientific community believes that because many of the lost whales were important matriarchal leaders, which then caused the social structures of the pods to collapse further, hindering the recovery of the South-Central Alaska orca population.
One particular group of transient Orcas appears to be in rapid decline after the Exxon Valdez oil spill. This group is seldom seen now and many members have not been spotted for years. The scientific community believes that this group of Orcas, their dialect and knowledge, will become extinct in the near future.
Orcas' Impact on their Ecosystem
Recently a scientific paper was circulated suggesting that orcas have been responsible for the rapid depletion of various localized marine mammal populations such as; sea lions, harbor seals, fur seals, and sea otters. The authors of this scientific paper argue convincingly that orcas shifted their feeding efforts to these smaller marine mammals after modern industrial whaling eliminated the orcas’ traditional diet of great whales (a group including all baleen whales and the sperm whale, which is toothed). In the North Pacific alone, half a million great whales were harvested between 1949 and 1969 by commercial whalers. By the mid 1970’s, all great whale stocks in the North Pacific Ocean were severely diminished.
If this theory is true, and the available data does indeed support this theory, commercial whaling in the North Pacific over 50 years ago would be responsible for not only the decline of great whale populations, but also the decline of other marine mammals. With the loss of large amounts of animals such as sea otters, the foods which they prey on, such as sea urchins, would consequently increase. With an increase in the stocks of urchins, which are near coastal grazers feeding primarily on kelp, there would be a drastic shift downward in the coastal kelp forest abundance, possibly impacting the entire coastal ecosystem. It’s quite possible that commercial whaling in the North Pacific Ocean over 50 years ago, set off one of the longest and most complex ecological chain reactions ever described.
For the 2012 season , we have shoulder season pricing, a new Backcountry Ski Cruise and more Land & Sea Cruise Adventures with our partners Camp Denali/North Face Lodge, Alaska Alpine Adventures, and Orca Adventure Lodge.
Cruise West closed down in Fall 2010. Looking for an alternative to Cruise West? Discovery Voyages offers the best small cruises in Prince William Sound, Alaska.
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