Orca Observations

20 May 2010

In last week's Cast Your Vote, you picked the marine mammal that you most wanted to learn about. You chose an animal that the entire expedition team is eager to see. We have yet to see an Orca from our kayaks, but we will keep our eyes peeled and our video camera at the ready as we head north. As soon as we get any photos or video footage, we will be sure to share it with you.

In the meantime, researching the Orca has been very interesting and rewarding. If you learn any information that we have not already posted, we encourage you to share it with us and your peers by posting a comment.

The scientific name for the Orca (sometimes called Killer Whale) is Ornicus orca. They are the largest members of the oceanic dolphin family. Orcas are top predators and they can be found in all of the world's oceans. Orcas have a black back, white chest and sides, and a white patch above and behind the eye. Their large tails help them move through the water and they use their two flippers for steering and balance. In order to stay warm, they have a thick layer of fat or blubber. They have sharp teeth. Male adult killer whales can reach up to 32 feet (9.8 m) in length and can weigh nearly 22,000 pounds (10,000 kg); females can reach 28 feet (8.5 m) in length and can weigh up to 16,500 pounds (7,500 kg). They can live from 25 to 90 years.

Orcas use underwater sound or echolocation for orientation, feeding, and communication. They are quite smart and social animals. They travel together in groups, called pods. Often, they will coordinate hunting as a group, like a pack of wolves.

There are three distinct types of Orca: resident, transient, and offshore. Resident Orcas tend to have a very well defined home range. Their group size ranges from five to twenty animals. They also primarily eat salmon. Two groups of resident Orcas can be found along the Pacific coast of North America. The southern residents live along the coast of Southern British Columbia and Washington. There are about 80 southern resident Orcas. They are grouped into three separate pods. The northern residents live along the coast of south eastern Alaska. There are about 200 of the northern resident Orcas, living in 16 separate pods. Resident Orcas are most likely to be seen close to shore between late spring to fall-- especially during salmon runs. They can eat up to 110-220 lbs (50-100 kg) of fish, squid and other food every day.

The transient or migratory whales eat mostly seals and sea lions and they travel greater distances than the resident Orcas, but they will still be found near shore. Transient Orcas travel in small groups of two to six individuals. Oftentimes their fins have nicks and scars on their dorsal fins. In total, about 300 transient Orcas roam the waters between Alaska and California.

Offshore Orcas travel far from shore and hunt schools of fish. They tend to be smaller than resident and transient Orcas. Offshore Orcas have most often been seen near the West side of Vancouver Island and in the Queen Charlotte Islands. These Orcas tend to travel in big groups of 20-75 individuals. Relatively little is know about this type of Orca.

Many modern Orca research practices were developed by a Canadian marine biologist named Michael Bigg. He discovered that it is possible to identify individual Orcas by photographing their dorsal fins and saddle patches (the light colored patch just under their dorsal fins). Individuals could be identified by the unique nicks, scratches, and tears on their dorsal fins and the shape of their saddle patch. This technique allowed researchers to count whales instead of just estimating population size. Researchers are also able to conduct long term studies, keeping track of individual's social interactions and travel patterns. There are several interesting studies going on, observing Orca conservation issues. It seems that the three main threats to Orcas are food shortages, industrial contaminants, and vessel disturbances. Perhaps some of you will follow in Michael Bigg's footsteps and make even more discoveries about this amazing marine mammal.

To learn more about Orcas, check out the links below:

http://www.pwlf.org/killerwhale.htm

http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/killerwhale.htm

http://www.nwr.noaa.gov/Marine-Mammals/Whales-Dolphins-Porpoise/Killer-Whales/

http://eol.org/pages/328534

http://www.pwlf.org/killerwhale/conservation.htm

http://www.whalesongs.org/