ORCA - KILLER WHALE Orcinus orca Some information obtained from the California Marine Mammal Center web site. Orcas are the largest member of the dolphin family; with males reaching 30 feet in length and weighing over 8 tons, and females reaching 22 feet and weighing four tons. Their ubiquitous dorsal fin can reach up to six feet in height. Orcas are found in most oceans of the world, but favor the areas where there is cool coastal water. They are very social animals with pods or groups containing up to 50 individuals. Based upon many years of research, scientists have concluded that there are three distinctive populations of orca pods: residents, transients, and offshores. Each of these sub-groups live in a matriarchal society and has its own distinctive behavior, ranging from food preference to the size of the pod. Residents tend to eat primarily fish while transients, by hunting in groups are able to hunt primarily marine mammals, including animals as large as blue whales. The offshore population feed mainly on squid and fish. Orcas weigh about 400 pounds at birth and are about 6 feet in length. Gestation lasts 16-17 months, and they nurse for a full two years. Most births occur in autumn and winter. . The original name of these whales was "whale killer", as they were often observed feeding on other whales. The name was erroneously changed to "killer whale" which is a misnomer, as there are no confirmed records of orcas killing a person in the wild. There has been a 20% decline in the Pacific Northwest population of orcas over the last five years. The reasons why the pods in this area are declining so rapidly are depletion of prey, marine toxins, acoustic harassment, and the destruction of habitat (the nurseries of the Inland Sea). The main prey source of this population of orcas, wild salmon, is being threatened by salmon farming. Bacteria spread by these farm-raised salmon are only one source of the problem. Sound is another problem. Salmon farms broadcast underwater noise at very loud volume to repel seals and this also forces the orcas to avoid these areas. Polychlorinated biphenyls (PCBs),a dangerous pollutant, is still a problem to orcas, despite being banned in the United States in the 1970s. These dangerous chemicals have accumulated in the food chain, especially in bottom feeding fish. Since the orcas are forced to eat these fish instead of the salmon, they accumulate more and more toxins. MORE ABOUT ORCAS Center for Biological Diversity Orca Live National Marine Mammal Laboratory ORCA CONSERVATION ORGANIZATIONS Raincoast Research Society Project Sea Wolf Center for Whale Research Raiancoast Conservation Society