cavity of a freshly caught sandbar shark, Car- 

 charhinus milherti, was accidentally opened. 

 From January through May of 1978, increasing 

 numbers of sandbar sharks with isopods in the 

 gills and heart were taken. By spring, infestation 

 was noted also in tiger sharks, Galeocerdo cuvieri, 

 including one living animal in which isopods had 

 entered the peritoneal cavity by chewing through 

 the musculature from the right pectoral fin axil. 

 Moderate isopod infestation of the gills was seen 

 in one individual of a third shark species ( Sphyrna 

 sp.) in August 1978. Scavenging by isopods of dead 

 sharks on setlines also increased dramatically 

 during this period. 



Shark catch declined sharply in June 1978, and 

 up to 607c of the animals that were taken were 

 affected by C. borealis (an average of 12 out of 20 

 sharks caught/400 hook set). The incidence rose to 

 lOO'/f of catch by August 1978 (an average of 22 

 sharks caught/400 hook set). Some of the sharks 

 retrieved alive with isopods in their hearts showed 

 no obvious external damage. A short pilot study in 

 October 1978 identified the problem in the shark 

 fishery (Bird^). Investigation was undertaken 

 from June 1979 through April 1980 on the occur- 

 rence of C. borealis, the possible species of fishes 

 affected, and the potential threat that the isopod 

 posed to fisheries on the Florida Atlantic coast. 



Cirolana borealis is normally a deepwater 

 isopod. Its distribution on both sides of the Atlan- 

 tic Ocean (usually at depths of 55-1,478 m) is 

 temperature and Gulf Stream related (Richardson 

 1904; Schultz 1969). (One individual, a male, was 

 noted by Menzies and Kruczynski (in press) in the 

 Gulf of Mexico in 1967 at a depth of 55 m.) The 

 occurrence in 1977 and 1978 off the Florida east 

 coast in depths as shallow as 20 m appears to be a 

 record for the species in that area. Cirolana 

 borealis is eminently carnivorous, an active swim- 

 mer, and reputedly a voracious scavenger and 

 has been noted as an occasional parasite by Sars 

 (1899), Richardson (1905), and Halvorsen (1966). 

 The species was recorded by Moreira and Sadow- 

 sky (1978) as an ectoparasite of Squalus spp. and 

 Raja spp.; it was also recorded in the peritoneal 

 cavity of Raja spp. Cirolana borealis is a mor- 

 phologically capable predator. The incisors are 

 heavily sclerotized for biting; the first three pairs 



^Bird, P. M. 1978. Report on infestation by Cirolana 

 borealis in sharks cauglit commerciallv on the Florida east 

 coast. Fla. Sea Grant Rep. 04-8-M01-76, 14 p. Florida Sea 

 Grant College, 2001 McCarty Hall, University of Florida, 

 Gainesville, FL 32611. 



of pereopods are prehensile, and the posterior 

 pereopods are ambulatory (modified natatory). 



The life cycles of most isopods are unknown 

 (Overstreet 1978). There are few studies on the 

 genus Cirolana other than those by Davis (1964), 

 Nielsen and Stromberg (1965), Tjonneland et al. 

 (1975), and Johnson (1976a, b). Cirolanids are not 

 considered endoparasitic. 



Methods 



Fishes examined for isopods during the course of 

 the investigation included commercially caught 

 Lutjanus campechanus, Epinephelus morio, and 

 Mycteroperca microlepis and numerous inshore 

 and offshore species (Dasyatis sabina. Raja eglan- 

 teria, Paralichthys lethostigma, Centropristis 

 striata, Rhomboplites aurora bens, Sphyraena 

 barracuda, Coryphaena hippurus, Haemulon 

 plumieri, Euthynnus alletteratus , Echeneis nau- 

 crates, Balistes capriscus, etc.) from fishing tour- 

 naments, shore fishermen, research vessels, and 

 personal collection. Swordfish, Xiphias gladius, 

 longline operations covering offshore areas from 

 north of Cuba to Georgia were accompanied and 

 their coincidental shark catches inspected for 

 Cirolana borealis. Twenty-three species of sharks 

 were examined altogether, including Carcha- 

 rhinus milberti, C. falciformis, C. limbatus, C. 

 obscurus, Galeocerdo cuvieri, Sphyrna mokarran, 

 Isurus oxyrinchus, and Ginglymostoma cirratum. 



As an adjunct to sampling, four seasonal field 

 trails were undertaken at sites where infested 

 sharks had been collected on setlines in 1978. Sites 

 were "baited" for isopods with living and dead 

 sharks placed on weighted lines and in wire cages 

 on the bottom. Additionally, bottom samples from 

 the area were obtained from shrimp and scallop 

 trawlers. They were subsequently treated with 

 rose bengal to stain organic material and screened 

 for isopods. Faunal records and recent and historic 

 benthic surveys were scrutinized for Cirolana 

 borealis occurrence. Historic water parameters, 

 currents, and eddies of the Florida Atlantic con- 

 tinental shelf were studied in regard to normal 

 patterns and possible deviations. 



Five shark samples with intact isopods were 

 obtained. All samples were initially frozen and 

 transferred into 10^ buffered Formalin^ on re- 

 ceipt. Samples 1 through 4 represented isolated 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



377 



