RANDALL: SURVEY OF CIGUATERA AT MARSHALL ISLANDS 



Enewetak and sent frozen to the Laboratory of 

 Marine Biochemistry of the University of Tokyo. 

 The specimens, which weighed from 130 to 230 g 

 each, were pooled in groups of three (four for one 

 group). The flesh and the viscera were separated 

 for each group, and the gut contents of all groups 

 were pooled. Fat-soluble and water-soluble frac- 

 tions were prepared and injected intraperitoneally 

 into mice at doses of 4,000, 2,000, and 1,000 ^g/g- 

 Two mice were used for each dose. If the mice were 

 not killed by a dose of 4,000 ;Ltg/g within the obser- 

 vation period of 48 h, the preparation was re- 

 garded as nontoxic. If they were killed by a dose of 

 1,000 iJ-g/g, it was classified as strongly toxic, at 

 2,000 ixg/g moderately toxic, and at 4,000 /xg/g 

 weakly toxic. The results were reported in a letter 

 by the late Yoshiro Hashimoto, then the Director 

 of the Laboratory. None of the preparations were 

 strongly toxic. All the preparations from the flesh 

 were nontoxic. Four of the seven fat-soluble prep- 

 arations of the viscera were moderately toxic, one 

 was weakly toxic, and one nontoxic. Five of the 

 seven water-soluble fractions from the viscera 

 were weakly toxic and the remaining two non- 

 toxic. Both the fat-soluble and the water-soluble 

 preparations of the pooled gut contents were mod- 

 erately toxic. 



The food habits and mode of feeding of C. 

 strigosus from the Hawaiian Islands were investi- 

 gated by Randall (1955b); underwater observa- 

 tions of C. striatus indicate that its feeding is es- 

 sentially the same. These fishes are detritus 

 feeders. From a near- vertical position (if the bot- 

 tom is horizontal) about 15 mm above the sub- 

 stratum, the fish move abruptly downward with 

 mouth open. The lips and teeth scrape over the 

 surface at the same time that suction is initiated. 

 The soft detrital material and fine inorganic sedi- 

 ment are ingested. If coarse particles of sand are 

 picked up, they are forcefully ejected. The stomach 

 contents of seven adults of C. strigosus from 

 Hawaii consisted of inorganic sediment (up to 90^ 

 by volume); fragments of red, green, and blue- 

 green algae; diatoms; and unidentified soft or- 

 ganic material. In an aquarium experiment C. 

 strigosus was unable to feed on an intact thallus of 

 the filamentous alga Polysiphonia sp. When the 

 same algae was finely fragmented and placed on 

 the bottom, it was readily consumed. 



Baiistidae (Triggerfishes) 



Pseudobalistes flavimarginatus (Riippell) (Fig- 



ure 50): This is one of three large species of trig- 

 gerfishes that occur in the Marshall Islands. It 

 may be distinguished from other balistids by the 

 following characters collectively: the second dor- 

 sal and anal fins elevated anteriorly, five or six 

 rows of spines on the caudal peduncle, no scales on 

 the cheek (of adults), caudal fin of adults emargin- 

 ate, and yellowish margins on the median fins. 

 Woods in Schultz and collaborators (1966) failed 

 to list this species from the Marshall Islands, but 

 the color plate in Hiyama ( 1943, pi. 22, fig. 61) and 

 the study of Hiatt and Strasburg (1960) clearly 

 indicate its presence there. Hiatt and Strasburg 

 stated that it is solitary, uncommon, and occurs on 

 lagoon and interisland reefs in quiet water of 

 10-30 ft (3.1-9.1 m) deep. Although Hiyama wrote 

 that this fish was not regarded as poisonous in the 

 Marshalls, other records (Halstead 1967) dem- 

 onstrate its capacity for causing ciguatera. It is 

 one of the nine species of fishes forbidden to be sold 

 in the fish market in Papeete, Tahiti (Bagnis 

 1968). 



Two specimens, 465 and 535 mm SL, weight not 

 taken, were collected in Bikini. Neither was 

 poisonous. 



Clark and Gohar (1953) reported pieces of 

 branched coral (Stylophora) 2-3 cm long in the 

 stomach of a specimen 440 mm SL from the Red 

 Sea. Hiatt and Strasburg (1960) examined two 

 stomachs from the Marshall Islands. They found 

 the crustacean Lydia annulipes and isopods, 

 crushed gastropods including Oliva sp., foraminif- 

 era, and colonial tunicate fragments. 



The stomach and gut contents of only two 

 specimens were obtained for the present study. 

 One of 254 mm SL from the Red Sea was empty. 

 The second of 390 mm SL from Tahiti had eaten 

 Diadema. 



Balistoides uiridescens (Bloch and Schneider) 

 (Figure 51): This is another large triggerfish for 

 which there have been a few records of toxicity. It 

 shares the elevated anterior part of the second 

 dorsal and anal fins and the rows of spines on the 

 caudal peduncle with P. flavimarginatus, but is 

 differentiated by having its cheek totally scaled 

 and its caudal fin rounded to slightly double emar- 

 ginate as an adult; also the margins of its median 

 fins are broadly blackish. It ranges from the Red 

 Sea to eastern Oceania. It occurs in both lagoons 

 and outer reef slopes. Like other triggerfishes, it 

 has a favorite hiding place in the reef into which it 

 wedges itself when threatened. 



243 



