. The Canadian field-naturalist. 1991 Houston: Status of Cuvier'S Beaked Whale 217 160 140 120 100 80 60 40 20 0. Figure 2. Distribution of Cuvier's Beaked Whale, Ziphius cavirostris. age at 30 GLGs (growth layer groups) for a female and 36 GLGs for a male (the term is generic and may correspond to the amount of hard tissue formed during one year). Oshumi (1964) has studied ovarian material, but insufficient sample sizes precluded conclusions on life-cycle or age (see also Mead 1984). The gestation period is not known, but calves appear to be born year round (Watson 1981). Foetal length has be
. The Canadian field-naturalist. 1991 Houston: Status of Cuvier'S Beaked Whale 217 160 140 120 100 80 60 40 20 0. Figure 2. Distribution of Cuvier's Beaked Whale, Ziphius cavirostris. age at 30 GLGs (growth layer groups) for a female and 36 GLGs for a male (the term is generic and may correspond to the amount of hard tissue formed during one year). Oshumi (1964) has studied ovarian material, but insufficient sample sizes precluded conclusions on life-cycle or age (see also Mead 1984). The gestation period is not known, but calves appear to be born year round (Watson 1981). Foetal length has been reported to vary from to m and a mean estimates for length at birth at m (Mead 1984). Solitary bulls are occasionally seen (Watson 1981; Hoyt 1984) but these whales are most frequently observed in pods of three to five individuals. Larger groups of 10 to 15 may represent extended families (Watson 1981). Gaskin (1981, 1982) indicates that the beaked whales are the least social of the medium-sized odontocetes which may account for the lack of mass strandings, even though the species strands more often than other ziphiids (Watson 1981). There is no evidence of migratory behaviour by the species (Gaskin 1972) but there may be some general north-south movements (Watson 1981). The reason for strandings of this species are still unknown (Watson 1981), but the fact that the species is found beached more often than other ziphiids may reflect an ubiquitous distribution and greater relative abundance. Cuvier's Beaked Whales are strong swimmers but usually travel at a leisurely pace of 5 to 6 kph. On deeper dives, the average submersed time is about 30 minutes. Deep dives may be preceded by a vertical raising of the fluke. The animals are also known to breach occasionally (see Watson 1981; Hoyt 1984). Limiting Factors None known. The species is exploited commer- cially along the coast of Japan (Omura et al. 1955) but there is no firm evidence that the species is being overfi
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