Kyne & Simpfendorfer.. - Shark Specialist Group

and in the case of the crocodile shark, two embryos develop in each uterus by feeding on ova
in uterine egg capsules (litter size is thus four) (Fujita 1981, Compagno 2001). Maturity has
been reported at 740mm TL in males and 890mm TL in females, with a maximum size of
1100mm TL (Compagno 2001).
Family Mitsukurinidae. Goblin Sharks.
The biology of the rare goblin shark Mitsukurina owstoni remains very poorly-known due to
its infrequent capture and observation (Duffy 1997). Although widely-distributed, a fair
proportion of records for the species come from Japan (Duffy 1997). However, an exceptional
capture of >100 individuals occurred in Taiwan over a two week period in 2003 (Duffy et al.
2004).
The species' mode of reproduction is unknown as gravid females have never been observed
by scientists, but as with other lamnoid sharks, the species is probably oophagous with small
litter sizes (Compagno 2001, Duffy et al. 2004). The goblin shark is one of the largest species
of elasmobranch, Parsons et al. (2002) reporting that it grows to 5400–6170mm TL. Mature
males of 2640, 3200 and 3840mm TL and a mature female of 3350mm TL have been reported
(Compagno 2001).
Family Alopiidae. Thresher Sharks.
Like other lamnoids, thresher sharks are oophagous (Gilmore 1993, Musick and Ellis 2005).
The reproductive biology of the bigeye thresher Alopias superciliosus is reasonably well
documented (see review in Gilmore 1993). A litter size of two (one embryo per uteri) has
been confirmed for the species (Gubanov 1979, Gilmore 1983, 1993, Moreno and Morón
1992, Chen et al. 1997), although litter sizes of 3 or 4 also occur less regularly (Compagno
2001).
Chen et al. (1997) found gravid females throughout the year off Taiwan in the Northwest
Pacific, with no defined mating or pupping season. Similarly, Moreno and Morón (1992)
could not find evidence of a well defined breeding season in the Eastern Central Atlantic,
although they suggested a possible preferential pupping season in autumn-winter. Without
defined reproductive seasonality it is difficult to determine gestation period, although it has
been estimated as 12 months in the bigeye thresher (Holden 1974). Diel vertical migration
patterns in A. superciliosus (Nakano et al. 2003, Weng and Block 2004) are discussed later in
this Section (see page 104).
Estimates of maturity and size at birth vary regionally and these are summarized in Gilmore
(1993) and Chen et al. (1997). Size at maturity equates to 76–79%TL max in females and to 67–
79 TL max in males, and size at birth ranges from 600–1400mm TL (Chen et al. 1997). Verified
age estimates for A. superciliosus from Taiwan gives longevities of 20 years and 19 years for
females and males, respectively (Liu et al. 1998) (Table 2.10).
Table 2.10. Age and growth parameters for Alopias superciliosus from Taiwan, Northwest
Pacific (Liu et al. 1998). von Bertalanffy growth model (VBGM) parameters: L ∞ (mm TL), k
(year -1 ), t 0 (years); t max oldest fish (years), A mat age at maturity (years).
VBGM parameters
Sex L ∞ k t 0 t max A max
♀ 2246 0.092 -4.21 20 12.3-13.4
♂ 2188 0.088 -4.24 19 9-10
82