Vertebrates that live in and by the sea are faced with serious challenges, as the sea is essentially a desert in terms of the availability of fresh water needed for osmoregulation and the maintenance of water and electrolyte homeostasis. How birds and mammals contend with this is still, in many cases, a matter of speculation, especially in the case of mammals such as seals and cetaceans. Ecophysiological studies of marine birds and mammals are still very much in their infancy but recent advances in radiotelemetry and satellite monitoring are rapidly revolutionising what we know of them. Some recent data will be reviewed in this chapter.

Albatrosses

Perhaps the most exciting data to emerge in recent years concern the flight paths of the wandering albatross, Diomedea exulans, in the Southern Ocean between the continents of Africa, Australia and Antarctica. These spectacular birds (Figure 8.1) spend more than 95% of their life in the open ocean, ten years of this as immature birds, and half of their mature life during non-breeding years. The long-term survival of these birds is now threatened by the activity of Asian long-line fisheries operating in the Southern Ocean. Brothers (1991) estimated that in one year alone, 1988, some 44 000 albatrosses were killed by taking baits set behind Japanese long-line fishing boats, 9600 of these being wandering albatrosses.