(from "The Research on the Whale Stock in the Antarctic - The Result of the Preliminary Study in 1987/88", ICR, 1989)

In the almost total absence of knowledge on the biological properties of "schools" at the present stage, we have no choice but to start our study with the application of these criteria.

Confusion often arises in the usage of the terms denoting a sampling unit of whales such as "school", "aggregation" and "group", because there seems to be lack of clear definition of these terms. "School" is a term generally used when the composite members of a group have some evidence of social solidarity to a certain extent. Mammal schools are frequently composed of individuals that belong to the same blood group. In the case of whales, a cow and her calf are believed to constitute a school as a family group.

"Aggregation" refers to a gathering of schools. When groups of whales move or migrate in the same direction or share a common feeding ground, the term "aggregation" can be applied. The term "group" is used only when biological connotations are disregarded.

It has been observed that groups of whales collaborate during feeding. However, it has not yet been confirmed whether this behavior is typically observed within a group or whether it is collaboration between one group and another - in other words, the characteristics of an aggregation.

From the above observations, it might be more appropriate to interpret the term "school" used in the Japanese research program as "group". Because the term "group" is also used to describe other aspects, we have decided to use the expression "school" to avoid possible confusions.

The Southern Hemisphere minke whales tend to migrate in small schools but sometimes form aggregations consisting of several hundred animals. On the other hand, a majority of the minke whale stocks in the Northern Hemisphere are believed to act as individuals.

Among toothed whales, the school properties of sperm whales are relatively well known and analyses on their social structures are well under way. This owes to the information from census survey which has been conducted on three sperm whale schools through scientific permit in 1964 and 1965 in addition to the relative easiness of observing this species from the coasts.

Baleen whales generally do not form large groups. In recent years some people have come to believe that sound generated from humpback whales plays the role of keeping the group together during long-distance migrations. However, many scientists find it hard to accept the view that baleen whales are intelligent animals with complex social structures.

Consequently, it seems difficult to conclude that the social structure of groups (schools) of baleen whales is of highly advanced nature, and thus, it is believed to be a relatively primitive structure. The only continuing social structure is thought to be the pair of cow and calf.

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