28 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



tip sliark, Carcha/rhinus Umbahis, but whether 

 different species, subspecies, ov races^are involved 

 remains to be determined. 



In the last week of February 1958, ij was able 

 to get evidence that the edge of the Continental 

 Shelf off the Cai'olinas is indeed an important 

 wintering ground for immature milherfi. A 

 series of 25 tows with a modified Number 41 otter 

 trawl made by the Bureau of Commercial Fish- 

 eries exploratory vessel Del-aware while I was 

 aboard took 203 immature m-ilherti between the 

 offings of Cape Hatteras and Cape Lookout. In 

 one tow in 52 fathoms, 197 milberfi from 27 to 43 

 inches long were taken and in tliree other tows at 

 depths of about 50 fathoms 4 milherfi were 

 picked up. Tows made at other depths from 20 

 to 250 fathoms failed to catch milbertl. The 

 water temperature at the bottom at this time was 

 about 64° F. in 50 fathoms, but temperatures were 

 appreciably cooler, about 57° F., in both 30 

 fathoms and 80 fathoms. 



It is suggested tliat the 197 young milberti 

 taken in February 1958, were young of the year, 

 bom in the summer or early fall of 1957, and that 

 their average length of 34 inches represented 

 growth from birth of about 12 inches in approxi- 

 mately 7 months. However, if it is correct that 

 all of these young were born in 1957, some may 

 have grown as little as 5 inches and some more 

 than 20 inches. Such an irregular growth pat- 

 tern would help to explain some other facts of 

 the milherti life history, for example, the sea- 

 sonal differences in the vitamin-A potency of 

 adults taken by the shark fishery. 



In January and February 1945, I obtained two 

 boatloads of sharks from O. E. Holley, an expert 

 shark fisherman at Fort Myers, Fla. Of the 133 

 sharks brought in, 73 were adult E. miiherti and 

 none of the female E. milberti were gravid. The 

 27 males in the sample ranged from 74 to 84 

 inches in total length (average, 79 inches) and 

 weighed from 94 to 130 pounds (average, 113.7 

 pounds). The 46 females ranged from 72 to 90 

 inches in length (average, 82.3 inches) and 

 weighed from 102 to 184 pounds (average, 145.1 

 pounds). The specimens were weighed and meas- 

 ured about 36 hours after capture and the stom- 

 achs of all of the sharks were empty or nearly 

 empty. Weight among sharks of the same length 

 varied considerably. Thus, three 78-inch males 



weighed 94, 115, and 122 pounds, while eight 83- 

 inch females weighed 122, 127, 141, 142, 146, 148, 

 161, and 162 pounds, and six 78-inch females 

 weighed 102, 136, 147, 147, 154, and 164 pounds. 

 "Weights of livers, other viscera, fins, and eviscer- 

 ated carcasses were obtained, but unfortunately 

 when these weights were recorded they were tied 

 in solely with the totf^l weight of each shark. 

 Analysis of the figures gives some indication that 

 liver weights in female E. milberti contributed 

 disproportionately to total weights. Livers of 

 males weighed from 7 to 14 pounds and livers of 

 females from 7.25 to 31 pounds. The average 

 weight of 40 livers from females was 18.5 pounds. 



It would be convenient and would fit most of 

 the facts to assume that the growth of Eulamia 

 77vilherti is very rapid, but there is merely pre- 

 sumptive evidence for this. It is by no means the 

 only view that could be reasonably advanced and 

 it would be especially "weak for milberti for 

 which the immature part of the population is not 

 well known. Nevertheless, on the basis of little 

 real evidence I sugge.st that it is probable that 

 growth from birth to maturity takes about 2 years, 

 occasionally 1 year, rarely 3 yeare. 



The length uniformity indicated in table 3 for 

 both male and female adult milberti from differ- 

 ent seasons would be expected from a species with 

 determinate growth. Predictable adult size in 

 jL-elatively narrow ranges also characterizes other 

 species of Exihimia. Negaprimi, and pei-haps Car- 

 charhiims. On the other hand, it is presumed 

 that some individuals of Prionace and Pterolami- 

 ops continue growing after maturity to reach 

 abnormally large sizes. Records of Galeocerdo 

 more than 14 feet long are not uncommon in tlie 

 literature and some of these records apparently 

 are reliable and I accept them as such. Never- 

 theless, I have seen more than a thousand large 

 Galeocerdo from the Florida-West Indian region 

 and have measured all of the exceptionally large 

 ones that I have seen. None were found to exceed 

 14 feet in total lengtli. Great increase beyond 

 the usual adult size has been noted, however, for 

 Sphyrna sp.. the great hammerhead. In my 

 sample of 52 adult females, 5 were much larger 

 than would be expected. If, as indicated by my 

 sample, the usual size for adult female great 

 hammerheads is 10 to 12 feet, the attainment of 

 approximately 15 feet by 10 percent of the lot 



