North Atlantic Marine Mammals

Abstract

Marine mammals are a diverse, widespread, and significant component of North Atlantic marine ecosystems. Four of the five commonly recognized marine mammal taxa reside in the North Atlantic: cetaceans, sirenians, pinnipeds, and polar bears. A fifth taxon and sea and sea lions and fur seals (family Otariidae) have not inhabited the North Atlantic since at least the late Pleistocene. The systematics of marine mammals is still being disputed. Marine mammals occupy all North Atlantic marine regimes, tropical to polar, although species-specific ranges exist and distribution patterns are not uniform. The large-scale, nonrandom distribution of marine mammals is influenced by oceanographic features, whereas small-scale distributions are influenced by factors such as the animal's physiology, behavior, and ecology. The physical characteristics of the North Atlantic ecosystem critically influence marine mammal distribution. Although the ocean basin provides marine mammals with an open pathway that extends from the equator northward to the Arctic and includes adjacent bodies of water, the North Atlantic has many different ecosystems. Some adjacent seas, such as the Baltic and Mediterranean, are more isolated from the open ocean and form separate ecosystems. Baleen whales are widely distributed in the North Atlantic, with individual species exhibiting preferences for certain ecosystems. Centuries of human activities have affected all North Atlantic marine mammal populations. Prehistoric people hunted coastal marine mammals for subsistence use, and in some areas aboriginal hunting still exists. Commercial exploitation of smaller cetaceans began in the fourteenth century when the Danes initiated organized hunts of Baltic Sea harbor porpoises.