1957. The smaller Cetacea of eastern Canadian waters. J. Fish. Res. Board Can. 14:83-115.
SERGEANT, D. E., A. W. MANSFIELD, and B. BECK.
1970. Inshore records of Cetacea of eastern Canada, 1949-68. J. Fish. Res. Board Can. 27:1903-1915.
1962. Whales. Hutchinson and Co., Ltd., Lond., 475 p. [There is also an American edition.]
1967. Cetacea. Mammals of the U.S.S.R. and adjacent countries. Isr. Program Sci. Transl., Jerusalem, Vol. IX, 717 p. [A compilation of worldwide data, originally published in Russian.]
1935. The distribution of certain whales as shown by logbook records of American whaleships. Zoologica (N.Y.) 19:1-50.
1889. Contributions to the natural history of the cetaceans, a review of the family Delphinidae. Bull. U.S. Natl. Mus. 36:1-192.
1964. Mammals of the world. The Johns Hopkins Press, Baltimore, p. 1083-1145. [Cetaceans. There is also a second, revised edition of this work, and a third, revised edition is planned.]
Field studies of cetaceans are very difficult. First, it is extremely hard to be positive that an individual or a group of animals is the same from one encounter to the next. This means that it is nearly impossible to determine, for example, whether herds of animals are resident in an area or only seasonal visitors. Without information of this kind, determinations vital to population management, such as sizes of populations and natural ranges, are impossible to make.
Secondly, as we frequently point out in this guide, individual cetaceans are usually visible to a surface observer only during the brief moments when they break the air-water interface to breathe. The majority of their vital activities (e.g., feeding, reproduction, communication, establishing and maintaining position within the herd, and defending against natural enemies) take place primarily below the surface, well out of view to a surface observer.
In recent years, in an attempt to overcome some of these problems, scientists have been placing markers on various species of cetaceans and monitoring their movements. The following brief summary of major methods of tagging cetaceans is provided to acquaint the reader with markers he may expect to see in the western North Atlantic.
Since their development in the mid-1920's, numerous Discovery marks (small stainless steel projectiles with identifying information stamped on them) have been shot into commercially valuable species by means of a shotgun. The recovery of these marks from whales subsequently killed in the whaling industry has provided valuable information on the movement patterns and on basic aspects of the growth and development of harvested species of whales. Discovery marks are limited, however, because they are not visible in a living animal. Reduction in whaling activities will bring about a significant reduction in their use.