988 



Fishery Bulletin 97(4), 1999 



The aim of this study was to investi- 

 gate the reproductive and feeding biol- 

 ogy of T. megalopterus. Investigations of 

 age and growth will be documented else- 

 where. Improved knowledge of this spe- 

 cies could underpin management strat- 

 egies for this component of the multi- 

 species shark fisheries off South Africa, 

 which' are known to be expanding 

 (Smale, 1997). 



Materials and methods 



Specimens were collected over a 12-year 

 period, between February 1984 and Oc- 

 tober 1996, from catches made with 

 hooks and lines by rock, surf, and ski- 

 boat fishermen. All specimens used in 

 this study were collected along the East- 

 ern Cape coastline between Cape St. 

 Francis (34°12'S; 24°52'E) and Coffee Bay (31°59'S; 

 29°09'E), South Afi^ca (Fig. 1 ). Specimens collected for 

 biological sampling were examined as soon as possible 

 after capture, or were fi-ozen for later study. Sharks 

 were measured to the nearest millimeter and, where 

 possible, weighed with a spring scale accurate to 100 

 g. Measurements of total length (TL) can vary consid- 

 erably depending on the placement of the caudal fin 

 during measurement ( Branstetter et al., 1987); in this 

 study TL was measured on a horizontal line between 

 perpendiculars, fi-om the tip of the nose to the tip of the 

 tail, with the tail at its maximum extension (Compagno, 

 1984). Total length is used throughout this paper, un- 

 less otherwise noted. 



Reproductive information was collected for 35 

 males and 87 females. Maturity stages largely fol- 

 lowed Bass et al. (1975), with minor modifications 

 (Goosen, 1997). Each specimen was assigned to one 

 of the reproductive stages: embryo, immature, ado- 

 lescent, mature, and, in females, pregnant. The 

 clasper was measured in length from the point of 

 outside insertion in the pelvic fin to the tip of the 

 clasper (CLO); from the point of insertion at the 

 cloaca to the tip of the clasper (CLI); and in width at 

 its thickest point (CBW) (Compagno, 1984). For fe- 

 males, the following data were collected: diameter of 

 the two largest ovarian eggs, width of the oviducal 

 gland, greatest width of the uterus, absence or pres- 

 ence of embryos and uterine eggs, and numbers of 

 embryos and eggs if present. 



Embryos were measured, sexed, and weighed. The 

 mean length of embryos in each litter was calculated 

 after abnormally developed individuals were ex- 

 cluded. Seasonality of mating, gestation period, and 



Durban 



Eastern Cape ♦Xoffee Bay 



East London 



'^Pon Elizabeth 

 Cape St Francis 



25' 30" 



35" 



Figure 1 



Southern Africa showing places mentioned in the text. 



pupping season were examined by comparing embryo 

 sizes in different months. Hepatosomatic indices 

 (HSI) were calculated from the formula 



HSI = iLWIBW) X 100, 



where LW = liver weight in grams; and 

 SW = total body weight in grams. 



Stomach contents were examined as soon as pos- 

 sible after capture, or frozen for later analysis. Prey 

 were identified to the lowest possible taxon. Excess 

 liquid was drained off and the mass of the remains 

 determined to the nearest 0.1 g on a top-loading pan 

 balance. Bait used to capture the sharks was ex- 

 cluded from analyses. 



Size measurements used for prey were carapace 

 width (CW) in crabs, mantle length (ML) in cephalo- 

 pods, and total length (TL) in teleosts and all other 

 prey. After whole fish prey were measured, otoliths 

 were removed to verify identification and paired, 

 counted, and measured. Otoliths were used to iden- 

 tify well-digested prey and to estimate their length. 

 Similarly, cephalopod beaks were collected, counted, 

 and measured. Neither formalin nor alcohol was used 

 to store stomach contents, because otoliths exposed 

 to such preservatives become etched or brittle (Smale 

 et al., 1995). Lengths of well-digested cephalopods 

 and teleosts were determined from regressions re- 

 lating beak and otolith lengths to body length ( Smale, 

 1983; Smale et al., 1993, 1995). Digested otoliths had 

 a chalky eroded appearance and were not measured 

 for use in prey size estimates. 



