72 Memoir Sears Foundation for Marine Research 



To class sharks "harmless" as a group, as some authors have done, is contrary to all 

 the weight of evidence. On the other hand, the danger of attack to the ordinary bather is 

 very small indeed, except in such special localities and under such circumstances as those 

 mentioned. 



Commercial Imfortance. Sharks are the objects of minor fisheries in the warmer 

 parts of the world, largely for their liver oil and for their fins (considered a great delicacy 

 by certain oriental races), and to a lesser extent for their hides and flesh. 



Shark liver oil was formerly valued highly in combination with other fish oils for 

 tanning, the yield from local fisheries being considerable, notably from the Greenland 

 Shark. Recently a new demand for the liver oil of some species has developed because of 

 the high vitamin content. This is notably the case in the northeastern Pacific, the California 

 catch having risen from about 555,000 pounds in 1936 to about 7,800,000 pounds in 1940, 

 although it dropped to 2,613,431 pounds in 1944, This increase has resulted from the oil 

 of one vitamin-rich species, the Soupfin or Oil Shark {Galeorhinus galeus). Interest in the 

 commercial possibilities of shark oil has given impetus to shark fisheries along the eastern 

 coast of the United States also, but to date no western Atlantic shark that occurs in large 

 numbers has been found to equal the California Galeorhinus in showing a consistently high 

 Vitamin A content (nor do representatives of that same species in the eastern Atlantic), 

 although individual specimens, such as the larger Hammerheads, may give a high yield. 

 The following table, condensed from a more detailed one,'^ gives the maximum and mini- 

 mum potencies in Vitamin A (stated in U. S. P. Units) for the liver oil of several Florida 

 sharks. 



Number of Potency 



Sfecies 

 Carcharodon carcharias 

 Ginglymostofna cirratum 

 Galeocerdo cuvier 

 Carcharhinus leucas 

 Carcharhinus milberti 

 Carcharhinus obscurus 

 Carcharhinus Umbatus 

 Negafrion brevirostris 

 Sphyrna diplana 34 137,000 5j400 



Sphyrna tudes many 340,000 8,250 



19. Springer and French (Industr. Engng. Chem., 56 [19], 1944: 190). See Walford (U.S. Fish Wild Life Serv., 

 Fish. Mkt. News, 6 [6], 1944: 4) for a detailed table giving the amounts of Vitamin A, both per gram of oil 

 and per pound of liver, for several species taken in the Gulf of California. For methods of calculating amounts 

 of Vitamin A in livers, see Sanford (U.S. Fish Wild Life Serv., Fish. Mkt. News, 7 [i], 1945: 6)and Bolomey 

 and Tompkins (Fish. Bull., Sacramento, 64, 1946: 73) ; for relationship between liver yield of Vitamin A and 

 the biology of the Soupfin Shark (Galeorhinus galeus) in California waters, see Ripley and Bolomey (Fish. 

 Bull., Sacramento, 64, 1946: 39). 



