FISHERY BULLETIN: VOL. 79, NO. 4 



squid fragments (mantles and beaks) from several 

 swordfish stomachs. They did not assign these 

 cephalopod remains to more specific taxa. Several 

 specimens contained "octopus javi^s." Their 

 study demonstrated ontogenetic changes in prey 

 selection, vi^ith adult Pacific swordfish feeding 

 principally on squid. Tibbo et al. (1961) examined 

 stomachs of 39 sw^ordfish from Nantucket Shoals 

 and Sable Island Bank, finding fish and the squid 

 Illex illecebrosus. In 14 of those swordfish (Sable 

 Island Bank specimens), 22 squid were included 

 among 564 food items. 



De Sylva (1962) analyzed stomachs of seven 

 female swordfish caught in April to May off 

 northern Chile. Of the five specimens containing 

 food remains, 24 squid Dosidicus gigas were 

 found. These findings led de Sylva to believe 

 that most swordfish feeding takes place near the 

 surface. Cavaliere (1963) reported swordfish diets 

 from the Straits of Messina and adjacent waters 

 during spring and summer. Cephalopods were 

 found in 80% of the stomachs with /. coindetii, 

 L. todarus i = Todarodes sagittatus ?), and Toda- 

 rodes sagittatus being most common. Guitart- 

 Manday (1964), reporting on an unspecified 

 number of swordfish taken during February and 

 March near Cuba, found teuthoids, including 

 Thysanoteuthis rhombus and a single octopod, 

 constituting approximately 30% of the diet by 

 number of items. Scott and Tibbo (1968), utilizing 

 volumetric analysis, examined stomach contents 

 of 514 swordfish from the western North Atlantic 

 between Virginia and Sable Island Banks. They 

 reported that, from March to October, swordfish 

 feed on /. illecebrosus, as well as on a variety of 

 fishes. Scott and Tibbo also noted the occurrence 

 of the squid Ommastrephes. Interestingly, they 

 reported the infrequent occurrence of the octopod, 

 Bathypolypus arcticus, a benthic inhabitant of the 

 continental shelf. 



Maksimov (1969) examined stomach contents 

 from 502 swordfish from the tropical Atlantic. 

 Frequency of occurrence and average size of food 

 items were reported. Cephalopods were a major 

 component of the diet in all areas sampled. The 

 following organisms were represented: Loligo 

 sp., Ommastrephes sp. (3 undetermined spp.), and 

 an undetermined species of sepioid. Ovchinnikov 

 (1970) noted cephalopod and fish remains by 

 percentage from swordfish taken near Cuba. They 

 are identical to those reported by Guitart-Manday 

 (1964) and probably are an uncited repetition of 

 the same data. Beckett (1974) reported swordfish 



diets from the northwest Atlantic. He indicated 

 that swordfish over deep water usually feed on 

 vertically migrating species including squids, 

 however, no further taxonomic breakdown was 

 given. 



MATERIALS AND METHODS 



Food remains from the stomachs of 65 speci- 

 mens of X. gladius from the Straits of Florida were 

 examined. Samples were obtained from three 

 sources: sportfishing tournaments in Miami and 

 Ft. Lauderdale, Fla. (38 specimens), commercial 

 longliners (23 specimens), and other sources (4 

 specimens). Collection data are given in Appendix 

 Table 1. 



Tournament swordfish specimens were mea- 

 sured and weighed at dockside. Weights of long- 

 line specimens were estimated using fork length- 

 weight relationships for both males and females 

 (Southeast Fisheries Center^). Stomachs were 

 removed and the contents fixed in 10% Formalin.^ 

 Following fixation, samples were transferred to 

 70% ethyl alcohol for storage. 



Analysis of individual stomachs was conducted 

 as follows. Contents were separated into squid, 

 fish, and other invertebrate components. Total 

 weights were taken for each group. Remains of 

 intact squid were further analyzed for individual 

 weight, dorsal mantle length, sex, state of matu- 

 rity, and general condition. Based on available 

 morphological features, squid were assigned to 

 the lowest possible taxa. Because of the poor 

 condition of many squid, numerous systematic 

 characters often were destroyed or unrecogniz- 

 able. Most species-specific diagnoses of teuthoid 

 cephalopods are based on external, soft-tissue 

 characters. It is just those features that are subject 

 to the intial effects of digestion. As a result, 

 identifications were based on a composite of less 

 frequently utilized morphological features that 

 are more resistant to digestive enzymes. These 

 included gladius and spermatophore morphology, 

 internal anatomy, dermal cartilage, mantle 

 musculature, photophore number and distribu- 

 tion, salient beak characters, and radulae. The 

 potential utility of such characters to predator- 



'^Southeast Fisheries Center. 1981. Report of the ICCAT 

 Inter-sessional Workshop on Billfish. Natl. Mar Fish. Serv., 

 Southeast Fish. Cent., Miami, Fla., Doc. 8, 16 p. Unpubl. 

 manuscr. 



■' Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



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