Commercial Shark Fishing in the Caribbean Area 121 



Figure 43 



Family. Eulamidae 



Genus Prionace, Blue Sharks. No piracies; no longitudinal 

 ridges on sides of caudal peduncle ; fur: . on upper jaw so short 

 that it is apt to be overlooked and none n the lower ; mid-point 

 of first dorsal fin is considerably nearer t the origin of the pelvics 

 than to axil (armpit) of the pectoral. 



Figure 43. Prionace glauca, Great Blue Shark. 



Description: Trunk noticeably slender; snout conical with nar- 

 rowly rounded tip and noticeably long; gill openings short, the 

 longest about as long as the horizontal diameter of the eye (this 

 relationship alters somewhat with growth) ; in the upper jaw there 

 are 14 teeth on each side (sometimes with smaller tooth at the 

 center), and in the lower jaw 13 to 15 on each side with 1 to 4 

 small ones in the center, uppers a little broader than long, oblique, 

 their outer margins deeply concave and inner margins convex and 

 their edges serrate; lower erect, more slender than uppers, usually 

 very finely serrate but occasionally smooth ; base of second dorsal 

 fin about 1/2 as long as base of first dorsal; caudal with narrowly 

 pointed tip and lower lobe, the latter about 1/2 as long as the upper 

 lobe; anal similar, a little smaller than the second dorsal and below 

 it ; pelvics noticeably small, being about as large as the anal ; 

 pectoral noticeably long (about as long as the distance from end 

 of snout to the fifth gill opening) ; only about 1/3 as broad as long, 

 with moderately convex front and concave distal margins and nar- 

 row tip. 



Color: Living specimens are dark indigo-blue along the back, 

 shading to a clear bright blue along the sides and to snow-white 

 below. They soon fade after death to a slaty or sooty gray. 



Size: Born at a length of 20 to 30 inches and maturing at about 

 7 to 8 ft., the Blue Shark grows commonly to 10 to 12 ft. While 

 it is credited with reaching 15 to 20 feet, there is no positive proof 

 of this. Because of their slender build recorded weights are onlv 

 about 100 to 120 lbs. at 7 to 8 ft. and 150'to 200 lbs. at 9 feet. 



Habits: This is a shark of the high seas, its wanderings chiefly 

 governed by its search for food or as it may drift with some ocean 

 current. It is often seen at the surface and there is no reason to 

 suppose that it ever decends io any great depth. When not dis- 

 turbed it is rather sluggish, but it swims powerfully and swiftly 

 when in pursuit of prey. It feeds on whatever of the smaller school- 

 ing fishes are available locally. They also consume large quantities 

 of bottom fish on the Fishery Banks. No evidence of their preving 

 on larger animals while these are alive. Their habit of gathering 

 (probably following up the blood scent) to gorge on the carcasses 

 of whales has long been known among sperm-whalers, by whom 

 it has always been held in contempt. 



Range: In the tropical, subtropical and warm temperate belts 

 of all oceans it is known along the eastern coast of America as far 



