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Fishery Bulletin 97(4), 1999 



22-24 mo (Wourms, 1977; Nammack et al., 1985; 

 Hanchet, 1988; Wourms and Demski, 1993; Wourms, 

 1994). The gestation of frilled sharks, Chlamy- 

 doselachus anguineus, may be as long as three and a 

 half years (Tanaka et al., 1990). The proposed gesta- 

 tion of about 20 mo in T. megalopterus is longer than 

 the estimated 12 mo in Triakis seinifaciata (Castro, 

 1983; Talent, 1985; Smith and Abramson, 1990). If 

 the 20'-mo estimate is correct, any females that mate 

 shortly after parturition would have a resting period 

 of two to three months. Some mature but nonpreg- 

 nant females, however, show no sign of ovarian egg 

 growth and development at the same time that oth- 

 ers have large ovarian eggs or uterine eggs (or both) 

 and small fetuses. These resting females represented 

 36% of the sample of 11 mature females taken be- 

 tween May and August. These females probably skip 

 a year and have an extended reproductive break of 

 at least 12-15 mo, which would prolong the cycle to 

 at least 3 years for some individuals. On the other 

 hand, some pregnant females about to undergo par- 

 turition have large ovarian eggs, and these individu- 

 als may mate within a few months and apparently 

 forego the extended resting period. 



On the basis of embryo growth rates presented 

 above, mating and fertilization probably occur from 

 about October to early December Females carry term 

 embryos of 422-440 mm (largest embryos) between 

 the last week of May and the last week of August, 

 which would approximate the time of parturition. 

 Compagno's ( 1984 ) estimate of size at birth was much 

 smaller (300-320 mm) than that of our findings. From 

 observations of embryonic development, it was noted 

 that during the late stages of embryo development 

 (from ca. 400 mm), both external and internal yolks 

 were absent. The small amount of yellow substance 

 in the spiral valve was thought not to be an internal 

 yolk reserve, but the area of absorption. It was also 

 noted that each embryo was contained in a soft egg 

 case with ca. 500 mL of fluid (Goosen, 1997). Wourms 

 and Demski (1993) noted that in Squalus acanthias, 

 several months into the 22-mo gestation period, em- 

 bryos can ionoregulate and osmoregulate in a uter- 

 ine solution resembling seawater This might be the 

 case for T. megalopterus and could contribute to near- 

 term embryo nourishment until parturition occurs. 



The liver mass of a shark is a good index of the 

 shark's condition (Springer, 1960). In our study it was 

 found to fluctuate widely, particularly after matura- 

 tion. Seasonal variation in HSI of the lesser 

 sandshark (Rhinobatos annulatus) has been attrib- 

 uted to fluctuations in lipid content of the liver, which 

 has been correlated with reproductive condition in 

 females (Rossouw, 1987). Similar changes in HSI 

 have been recorded in pregnant females of three 



Mustelus species (King, 1984; Smale and Compagno, 

 1997). Although low HSI values were found in preg- 

 nant females with near-term embryos in this study, 

 the relation was not statistically significant, possi- 

 bly suggesting that HSI fluctuates with other physi- 

 ological factors. These observations were based on a 

 small sample size and need further investigation. 



Feeding 



This study showed that T. megalopterus changes diet 

 with growth, which suggests that it selects prey of 

 suitable size. Because there is no evidence to date of 

 marked habitat change with growth, and all sizes of 

 shark do not have the same prey, it is unlikely that 

 they are feeding opportunistically, even if they favor 

 abundant species. Opportunistic feeding sensu 

 Wetherbee et al. (1990) implies that stomach con- 

 tents are varied but of composition and abundance 

 similar to those of prey in the environment. Smale 

 ( 1996 ) noted that the term "opportunistic" should be 

 used with caution because it is difficult to distinguish 

 between abundance and availability. Ontogenetic 

 variation in feeding of T. megalopterus appears to be 

 attributable to broadening the diet to include more 

 energetically rewarding species (e.g. teleosts), al- 

 though benthic prey are still taken. 



Spotted gully sharks fed primarily on the crab 

 Plagusia chabrus; as sharks grew, larger individu- 

 als were taken. This finding conforms with those 

 where large crabs were taken by larger leopard 

 sharks (T. semifasciata,Ta\ent 1976). Although spot- 

 ted gully sharks are most abundant near reefs, they 

 may also hunt over sandy areas to exploit the crab 

 Ovalipes trimaculatus, which prefers sandy sub- 

 strates. Spotted gully sharks preyed largely on noc- 

 turnally active lobsters (Paterson, 1969; Smale, 1978; 

 Zoutendyk, 1988) and crabs (Brown, 1961; Warner, 

 1977), suggesting that they are nocturnal hunters 

 that take crustaceans as they emerge. Such activity 

 may explain why anglers catch them more frequently 

 at night. 



As the sharks increase in size, they use a much 

 wider variety of prey groups, including teleosts. 

 Therefore, with growth the spotted gully shark is able 

 to attack and ingest larger prey species. Nocturnally 

 hunting sharks may be able to take some teleosts 

 when they are less active or resting at night. Elas- 

 mobranchs became increasingly important prey with 

 growth, a finding that supports previous observations 

 of congeners taking elasmobranchs (Bass etal., 1975; 

 Russo, 1975; Talent, 1976; Compagno, 1984). 



Octopus vulgaris was the most common cephalo- 

 pod prey It inhabits reefs (Smale and Buchan, 1981; 

 Roper et al., 1984) and emerges from its den to hunt 



