Ecology of Japanese coastal orcas, including pod sizes, major travel pattern and routes has not been clearly understood, and it is apparent from the ﾒNatural Resources Evaluation Reportﾓ published by the Fisheries Agency. The population estimate is made from an analogical estimate using similar species whichﾕs population is under research by employing sight survey. It is said that there are 1,600 orcas in the Pacific Ocean side (from Bousou to Hokkaido approx.900), and 721 orcas in Okhotsk Sea.

There are a few different types of orcas according to their behavior. The major types divide into two: the Resident (stay closer to the shore, eat fish) and the Transient (travel more eat mammals). Which type the Japanese coastal orcas fall into is not yet understood.

On the other side of the Pacific Ocean along the west coast of North America, studies on orca societal structure and behavior have been showing great progress, using individual identification. Researchers concerned about the population decline due to heavy capture for aquarium displays during the 1970s carried out a studies and showed that there were only one thousand a little more for both residents and transients combined. Before the result came out it was believed that there were several thousand animals each. Considering this and the fact that there had been orca hunts along the coast of Japan in the past, it seems more logical to assume that there are fewer orcas than what is currently estimated. There is small private research stations set up in Japan working on small projects, but the government tends to shy away from doing research from animals with no merit in terms of natural resources.