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Abstract
Life-history parameters of Deania calcea and Deania quadrispinosa suggested that their
productivity was very low. Maturity (L(T50) ) occurs at c. 80% of maximum observed
total lengths (L(T) ) for both species and sexes. A large proportion of mature females
were neither pre-ovulatory nor pregnant, and the reproductive cycle included a distinct
resting phase after pregnancy. For D. calcea, mean ovarian fecundity was 12 and maximum
observed litter size was 10 (average of six); D. quadrispinosa averaged 17 pups per
litter. Birth L(T) was 28-33 cm for D. calcea and 23-25 cm for D. quadrispinosa.
The male and female reproductive cycles were aseasonal, and consequently, the length
of the reproductive cycle could not be determined. Preliminary ageing data from dorsal-spine
growth bands suggested that female D. calcea lived to 31-36 years and males to 24-32
years. The L(T) -at-age data using external bands on the spines showed maturity occurring
at 15·5 years (males) and 21·5 years (females), whereas banding on the internal dentine
indicated maturity at 10·5 and 17·5 years for males and females. Thus, a female lifetime
of 31-36 years allowed for a maximum of 7 litters if a 2 year cycle is assumed or
only five litters with a 3 year cycle, resulting in a lifetime fecundity of only 42
pups (2 year cycle) or even lower (3 year cycle).