edge of continental shelves, and bottom features, such as seamounts, canyons, escarpments, and oceanic islands, including the Azores and the Canary Islands, and even off the coasts of Hawaii. Life history Very little is known about the life history of beaked whales. The oldest recorded age is 84 years for a male Baird's beaked whale and 54 years for a female. For all other beaked whale species studied, the oldest recorded age is between 27 and 39 years. Sexual maturity is reached between seven and 15 years of age in Baird's beaked whales and northern bottlenose whales. Gestation varies greatly between species, lasting 17 months for Baird's beaked whales and 12 months for the northern bottlenose whale. No data are available on their reproductive rates. Determining group size for beaked whales is difficult, due to their inconspicuous surfacing behavior. Groups of beaked whales, defined as all individuals found in the same location at the same time, have been reported as ranging from one to 100 individuals. Nevertheless, some populations' group size has been estimated from repeated observations. For example, northern and southern bottlenose whales (H. ampullatus and H. planifrons), Cuvier's beaked whales, and Blainville's beaked whales (Mesoplodon densirostris) have a reported maximum group size of 20 individuals, with the average ranging from 2.5 to 3.5 individuals. Berardius species and Longman's beaked whales (Indopacetus pacificus) are found in larger groups of up to 100 individuals. Not much information is available about group composition of beaked whales. Only three species have been studied in any detail: northern bottlenose whales, Blainville's beaked whales, and Baird's beaked whales. Female northern bottlenose whales appear to form a loose network of social partners with no obvious long-term associations. In contrast to females, some male northern bottlenose whales have been repeatedly recorded together over several years, and possibly form long-term associations. Studies of Blainville's beaked whales have revealed groups usually consist of a number of females, calves, and/or juvenile animals. These whales are assumed to live in "harem-like" groups, where several females and young are accompanied by a single male. Baird's beaked whales are known to occur in multiple male groups, and in large groups consisting of adult animals of both sexes. Arnoux's beaked whales have also been observed to form large pods of up to 47 individuals off the Southern Ocean off the coast of Kemp Land, Antarctica. Conservation For many years, most beaked whale species