The following is a summary of the author's paper given at the Symposium on Diseases and Husbandry of Aquatic Mammals, Feb. 21 and 22, 1968, at Florida Atlantic University, Boca Raton, Florida.

Summary

The distribution and feeding habits are summarized for large whales (Mysticeti), small whales (Delphiidae, Delphinapteridae, Phocaenidae), and seals (Pinnipedia) of the northwest Atlantic Ocean.

The great whales (Balaenopteridae) show marked divergences in baleen structure and food preferences in the northwest Atlantic, with the more successful species (e.g. fin whale Balaenoptera physalus) exhibiting aerophagy and having a wide temperature tolerance, and others e.g. the blue whale (B. musculus) exhibiting stenophagy-- in this case restriction to crustacean prey, mostly Euphausiidae--and restriction of range, in this case to the Gulf of St. Lawrence and mid-west Greenland waters in summer.

The two sympatric species harbor seal, Phoca vitulinaand gray seal Halichoerus grypus in contrast show wide overlap of food species eaten but have almost opposite whelping seasons, so that the young do not compete for food (McLaren, 1966).

Pinnipedia can extend out to sea where ice development is extensive. Habitat relationships may then exist between Pinnipedia and Cetacea, e.g. the range of the harp seal Pagophilus groenlandicusand several of the Balaenopteridae touch but do not overlap and these contiguous ranges change seasonally as the ice advances and retreats. Even intra-specific competition in the harp seal is avoided by food specialization.

Thus, the habitat (Hutchinson, 1967) of a species of marine mammal can be defined by a number of parameters. Important among these are physical limits. Temperature may restrict the range of a species latitudinally. Depth of diving may limit a species to coastal waters, the continental shelf, or oceanic waters. Food is the most important biological parameter in that a species may be limited to a diet of pelagic Crustacea, pelagic squids, benthic lamellibranches, small pelagic fish, or large benthic fish, or at least to limited combinations of these ingredients.

It is demonstrated that many of these limitations are the result of inter-specific competition (competitive exclusion) which in the course of evolution has limited an individual species to a particular habitat, just as with the better-studied terrestrial animals. Concomitant structural and physiological specializations have evolved. The habitat of each species can be defined using a number of the criteria described above.

Figure 1. Distribution of Pinnipeds (Hair Seals and Walrus) in the northwest Atlantic.

Figure 2. Distribution of Porpoises and Dolphins in the northwest Atlantic

Figure 3. Distribution of certain large whales in summer in the northwest Atlantic.

Figure 4. Distribution of certain other large whales in summer in the northwest Atlantic

Selected Bibliography

A. General Works on Ecology and Zoogeography

1. Dunbar, M. J. 1949. The Pinnipedia of the Arctic and Sub-arctic. Bull. Fish. Res. Bd. Canada 82, 22 pp.
2. Hazen, William E., Ed. 1964. Readings in Population and Community Ecology, W. B. Saunders Co., Philadelphia & London, 388 pp.
3. Hutchinson, G. E. 1967. A Treatise on Limnology. Vol. II-Introduction to Lake Biology and the Limno-plankton. John Wiley and Sons, New York, London, Sydney, 1115 pp.
4. Klumov, S. K. 1961. Plankton and the feeding of whalebone whales (Mystacoceti). Trudy Instituta Okeanologii 51:142-156. (Fish. Res. Bd. Canada, Trans. Ser. No. 473)
5. Klumov, S. K. 1963. Feeding and helminth fauna of whalebone whales (Mystacoceti) in the main whaling grounds of the World ocean. Trudy Instituta Okeanologii 71:94-194. (Fish. Res. Bd. Canada, Trans. Ser. No. 589)

B. Faunal or Species Studies in the North Atlantic

1. Bree, P. J. H. van, and H. Nussen. 1964. On three specimens of Lagenorhyncus albifrontisGray 1846 (Mammalia, Cetacea). Beaufortia 11(139):85-92.
2. Fraser, F. C. 1953. Report on Cetacea stranded on the British coasts from 1938 to 1947. Brit. Mus. Nat. Hist., Rept. on Cetacea No. 18:48 pp.
3. Harington, C. R. 1966. Extralimital occurrences of walruses in the Canadian arctic.
4. J. Mammal. 47(3): 506-513.
5. Jonsgaard, Aa. 1966. Biology of the North Atlantic Fin Whale Balaenoptera physalus (L). Taxonomy, Distribution, Migration, and Food. Hvalraadets Skr. 49: 62 pp.
6. Mansfield, A. W. 1967. Seals of Arctic and Eastern Canada. Bull. Fish. Res. Bd. Canada No. 137: 35 pp.
7. McLaren, I. A. 1966. Taxonomy of Harbor Seals of the western North Atlantic and Evolution of Certain Other Hair Seals. J. Mammal. 47(3): 466-472.
8. Moore, J. C. 1966. Diagnoses and Distributions of Beaked Whales of the Genus Mesoplodon Known from North American Waters. In Whales, Dolphins, and Porpoises (Ed. K. Norris). Univ. Calif. Press, Berkeley and Los Angeles, pp. 32-61.
9. Sergeant, D. E. 1962. The biology of the pilot or pothead whale Globicephala melaena. (Traill) in Newfoundland waters. Bull. Fish. Res. Bd. Canada No. 132: 84 pp.
10. Sergeant, D. E., and H. D. Fisher. 1957. The smaller Cetacea of eastern Canadian waters. J. Fish. Res. Bd. Canada 14: 83-115.