164 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Table 8. — Comparison of certain characters from selected 

 specimens of the Atlantic sailfish and the unidentified 

 species 



Character 



Size 



Snout length 



Number of fin rays: 



Dorsal 



Anal 



Pectoral 



Size 



Snout length 



Snout extension 



Mandibular keels 



Number of fin rays: 



Dorsal 



Anal. -- 



Pectoral 



Longest dorsal fin ray . 



Dorsal fin, anterior 

 lobe. 



Dorsal fin, pigment. ., 



Pelvic fin rays. 



Size 



Snout length 



Snout extension . . . 

 Mandibular keels. 



Atlantic sailfish 



11.3 mm 



;s length of head . 



20.9 mm-.-- -. 



ii length of head . . . 

 ii length of snout . . 

 Noticeably serrate . 



Number of fin rays: 



Dorsal- 



Anal 



Pectoral 



Longest dorsal fin ray. 

 Dorsal fin, anterior 



lobe. 

 Dorsal fin, pigment. -. 



Pelvic fin rays.. 

 Body pigment-. 

 Dermal spines-- 



49 



23 



17 



Number 13 to 15 



Terminates at about the 



25th ray. 

 Extends posteriorly to 



25th ray. 

 Third is twice length of 



first. 



38.8-56.2 mm 



?5 to ?i length of head.. 

 ii to ?4 length of snout. 

 Present (minutely ser- 

 rate) . 



Unidentified species 



51-53---- ---- - 



24 



18-20 



Number 13 to 15 



Terminates at about the 

 40th ray. 



Extends posteriorly to 

 33-37th ray. 



Third is twice length of 

 first. 



Distinct barred or 

 blotched pattern. 



Discernible at 43 mm. 

 as spines which pro- 

 trude slightly through 

 skin, uniformly dis- 

 tributed over body. 



11.3 mm. 



\i length of head. 



42. 

 16. 

 14. 



21.0 mm. 

 H length of head. 

 M length of snout. 

 Minutely serrate. 



44. 



23. 



20. 



Number 5. 



Terminates at about the 



37th ray. 

 Extends posteriorly to 



37th ray. 

 First and third equal in 



length. 



45.0 mm. 



W length of head. 



M length of snout. 



Absent. 



49. 

 24. 



18. 



Number 13. 

 Terminates at about the 



40th ray. 

 Extends posteriorly to 



the 4Qth ray. 

 Third and first equal in 



length. 

 No bars or blotches. 



Distinct spines arising 

 from individual base 

 plates, uniformly dis- 

 tributed except for ir- 

 regularly sized patches 

 on body above lateral 

 line (skin has worm 

 track appearance). 

 (Dermal spines resem- 

 ble those in Beebe, 

 1941, text figure 2 for 

 Istiophonts greyi Jordan 

 & Hill— 84 mm.) 



FOOD HABITS 



Prior to Beebe's report (1941) that copepods are 

 the primary food of small sailfish, and Voss's ob- 

 servations (1953) on the food of postlarval and 

 juvenile sailfish, little is found on the subject in 

 the literature. The stomachs of 32 istiophorid 

 specimens from the Theodore N. Gill collections 

 were examined, and stomach contents are listed in 

 table 9. With reference to this table it should be 

 noted that copepods constituted the food of speci- 

 mens less than 6 mm. long. At this size fish larvae 

 also were eaten, and no specimen exceeding 13 

 mm. had copepods in its stomach. Voss (1953) 

 also found evidence of change in the diet of young 

 sailfish from copepods to fish larvae at a size of 

 approximately 6 mm. 



Of particular interest are the small istiophorids 

 removed from the stomachs of three of the speci- 



mens (one 10.2 mm. long from a 21.0-mm. speci- 

 men, one 6.6 mm. long from a 13.0-mm. specimen, 

 and part of one with a head 2.4 mm. long from a 

 16.2-mm. specimen). One specimen 6.0 mm. long 

 removed from the stomach of a 21.9-mm. sword- 

 fish {Xiphias gladius), Arata fl954), had copepods 

 in its stomach. An unidentified species of fish oc- 

 curred frequently in the stomachs of several speci- 

 mens taken 90 miles east of Brunswick, Ga., July 

 29, 1953, and flying fish predominated in the stom- 

 achs of others taken 150 miles east of Charleston, 

 S. C, August 10, 1953. During the collection of 

 the latter, small flying fish were also dipnetted. 

 Small istiophorids were "relatively abundant" in 

 the water when the above collections were made. 

 Some fish larvae were larger than half the length of 

 the fish that had eaten them. These data add 

 support to the theory advanced by previous 





_1_ 



I 



-J I I I I I I 



I 



J u 



I I I 



2 4 6 10 20 40 60 



STANDARD LENGTH MINUS SNOUT LENGTH, IN MM. 



FiGCRE 36. — Relation of snout length to standard length 

 minus snout length. Large black dots represent the 

 unidentified species. 



