RANDALL: SURVEY OF CIGUATERA AT MARSHALL ISLANDS 



Figure 5. — Carcharhinus limbatus, 1,415 mm PCL, 1,910 mm TL, 38.2 kg, Enewetak, Marshall Islands. 



The tips of the fins of Pacific individuals, particu- 

 larly adults, are only slightly tipped or edged in 

 black. Also the common Indo-West Pacific C. 

 melanopterus has very pronounced black tips on 

 its fins (see Randall and Helfman 1973, fig. 1, 2). 

 To avoid confusion in common names, C. melanop- 

 terus has been referred to by many recent authors 

 as the blacktip reef shark (though Bass et al. 1973, 

 call it the blackfin reef shark). 



Carcharhinus limbatus is distinctive in lacking 

 a median ridge on the back between the dorsal 

 fins, having a relatively long snout, and the cusp of 

 its teeth notably narrow and erect. It has 29-32 

 upper, 28-32 lower teeth, and 88-102 precaudal 

 vertebrae. The color is gray to bronze on the back, 

 white below, with a long band of the dark dorsal 

 color extending posteriorly from the last gill open- 

 ing into the pale ventral color as far as the pelvic 

 fins. 



Two individuals of C. limbatus were caught at 

 Enewetak during the ciguatera survey; these con- 

 stitute the first records of the species from the 

 Marshall Islands. The head of the illustrated 

 specimen (which was 1,415 mm PCL, 1,910 mm 

 TL, and weighed 38 kg) has been preserved in the 

 Bernice P. Bishop Museum under catalog number 

 18074. 



Only the second specimen, which was about 

 1,700 mm PCL (original data sheet with mea- 

 surements was lost), was tested for toxicity. The 

 viscera gave a reaction of 2 when fed to a 

 mongoose. 



Bassetal. (1973) reported on 55 of 101 sharks of 

 this species with food in their stomachs. Fifty-one 

 of the sharks had eaten teleost fishes, including: 



Scomberomorus commerson, S. leopardus, 

 Pomadasys sp., Sarpa salpa, Johnius 

 hololepidosus , Leiognathus equula, Flops saurus, 

 Tilapia mossambica, and a soleid. Six contained 

 elasmobranchs, including a small C. obscurus and 

 aRhinobatus annulatus. Two had eaten Sepia sp., 

 and one a spiny lobster, Panulirus homarus. 



The two Enewetak specimens had empty 

 stomachs. 



Galeocerdo cuvier (Peron and Lesueur) (Figure 

 6): The circumtropical tiger shark is readily iden- 

 tified by its broad bluntly rounded snout, distinc- 

 tive teeth (heavily serrate, convex on the medial 

 margin, and deeply notched on the lateral), low 

 longitudinal keel on the side of the caudal pedun- 

 cle, and dark bars (though these tend to fade with 

 age). 



The flesh of two tiger sharks from Enewetak, 

 1,770 and 2,410 PCL (72 and 174 kg), and one from 

 Bikini, 1,498 mm PCL, was tested. None of these 

 sharks were toxic. The Bikini specimen was 

 caught at 4:30 a.m. in only 1.7 m of water. 



Bigelow and Schroeder ( 1948) summarized the 

 literature on food habits, danger to man, etc., of 

 this shark. Other authors such as Clark and von 

 Schmidt ( 1965), Bass et al. (1975a), and Tester (see 

 footnote 7), have added to the list of the great 

 variety of marine animals (mainly fishes) that this 

 species will take as food, as well as sundry items of 

 garbage and refuse discarded into the sea by man. 



The stomach of the largest of the Marshall Is- 

 lands specimens contained the scutes of a green 

 turtle, Chelonia mydas, estimated to be 500 mm 

 carapace length and the bait (a gray reef shark). 



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