A SURVEY OF CIGUATERA AT ENEWETAK 



AND BIKINI, MARSHALL ISLANDS, WITH NOTES ON 



THE SYSTEMATICS AND FOOD HABITS OF CIGUATOXIC FISHES^ 



John E. Randall^ 



ABSTRACT 



A total of 551 specimens of 48 species of potentially ciguatoxic fishes from Enewetak and 256 specimens 

 of 23 species from Bikini, Marshall Islands, were tested for ciguatoxin by feeding liver or liver and 

 viscera from these fishes to mongooses at 10% body weight (except for sharks, when only muscle tissue 

 was used.) The fishes are representatives of the following families: Orectolobidae, Carcharhinidae, 

 Dasyatidae, Muraenidae, Holocentridae, Sphyraenidae, Mugilidae, Serranidae, Lutjanidae, Leth- 

 rinidae, Carangidae, Scombridae, Labridae, Scaridae, Acanthuridae, and Balistidae. The species 

 selected were all ones for which toxicity can be expected, including the worst offenders from reports of 

 ciguatera throughout Oceania; only moderate to large-sized adults were tested. In all, 37.3% of the 

 fishes fi-om Enewetak and 19. 7"%- from Bikini gave a positive reaction for ciguatoxin. Because liver and 

 other viscera are more toxic than muscle, the percentage of positive reactions at the level which might 

 cause illness in humans eating only the flesh of these fishes collectively would drop to 16.2 for 

 Enewetak and 1 .4 for Bikini. This level of toxicity is not regarded as high for Pacific islands, in general . 



Because ciguatoxin is acquired through feeding, the food habits of these fishes were investigated. 

 Most of the highly toxic species, including seven of the eight causing severe illness or death in the test 

 animals (Lycodontis javanicus , Cephalopholis argus, Epinephelus hoedtii, E. microdon , Plectropomus 

 leopardus, Aprion virescens, and Lutjanus bohar) are primarily piscivorous. Some such as Lethrinus 

 kallopterus (which also produced a mongoose death) feed mainly on echinoids and mollusks. Among the 

 larger herbivorous fishes that were tested, only one individual ofKyphosus and two ofScarus caused a 

 weak reaction in the test animals. 



In view of the importance of correct identification of the ciguatoxic fishes, diagnostic remarks and an 

 illustration are provided for each of the species tested. Some alteration in scientific names was 

 necessary for a few of the fishes. 



The Marshall Islands are the easternmost islands 

 of Micronesia and of the Trust Territory of the 

 Pacific Islands. They consist of 34 low islands, 

 most of which are atolls, and numerous reefs 

 which occur between lat. 4° 30' and 15° N and long. 

 161° and 173° E. They lie in two parallel groups in 

 a northeast-southwest direction, the easternmost 

 being the Ratak ("Sunrise") Chain and the west- 

 ernmost the Ralik ("Sunset") Chain. 



Two tj^jes offish poisoning are known from the 

 Marshall Islands: tetraodontid (puffer) poisoning 

 (Hiyama 1943; Yudkin 1944; Halstead 1967) and 

 ciguatera. This paper is restricted to the latter 

 toxemia. It results from the ingestion of a great 

 variety of tropical reef and semipelagic fishes. 

 Ciguatoxin is thermostable, hence unaffected by 

 cooking or freezing of the fishes. It is not the result 

 of decomposition but is present to a varying degree 



'Contribution of the Mid-Pacific Research Laboratory. 

 ^Bemice P. Bishop Museum, Box 19000-A, Honolulu, HI 

 96819. 



Manuscript accepted October 1979. 

 FISHERY BULLETIN: VOL. 78, NO. 2, 1980. 



in the different tissues of fishes when entirely 

 fresh. The severity of the illness and the 

 symptomatology depend upon the concentration of 

 the toxin and the amount of fish eaten; fatalities 

 are rare. Symptoms appear about 1-10 h after a 

 toxic fish is consumed; those most commonly given 

 are: weakness or prostration; diarrhea; tingling or 

 numbness of the lips, hands, and feet; confusion of 

 the sensations heat and cold; nausea; joint and 

 muscular pain; inability to coordinate voluntary 

 muscular movements; difficulty in breathing; 

 burning urination; and itching. Probably the most 

 common diagnostic symptoms are unpleasant 

 tingling sensations of the palms of the hands and 

 soles of the feet on contact with cool materials and 

 the feeling of heat when cold objects are touched or 

 cold liquids taken into the mouth. Light cases may 

 not exhibit these sensations, however. 



The Marshall Islands have long been known to 

 harbor ciguatoxic fishes. The earliest report from 

 these islands seems to be that of Steinbach ( 1895) 

 who wrote of fishes being toxic on the west side of 



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