242 BULLETIN OF THE BUREAU OF FISHERIES. 



were available at the time. With the exception of the two species of hammer-headed 

 sharks, the character of the teeth or denticles, or both, have been of value in identifjing 

 the species. 



The writer is indebted to the assistants at the Beaufort laboratory who aided in 

 this work; and also to Mr. Barton A. Bean, of the United States National Museum; 

 Mr. Russell J. Coles, of Danville, Va. ; Mr. Vinal N. Edwards, of the Woods Hole labora- 

 tory; Dr. E. W. Gudger, of Greensboro, N. C. ; and Mr. John T. Nichols, of the American 

 Museum of Natural History, for the use of material. 



UTILIZATION OF SHARKS AND RAYS. 



In the United States there is a prejudice against the use of this class of animals 

 for food that results in waste of what rightfully should be a resource. In England and 

 Wales, for example, 64,996 hundredweight of dogfish, valued at £20,242, were landed 

 in 1 91 3. As the flesh of these small sharks, when properly prepared, is palatable, there 

 appears to be no valid reason against its use. The United States Bureau of Fisheries 

 has been conducting preliminary experiments in the preparation of this meat, and there 

 is good ground for the belief that a demand for the article will be created. Even now 

 sharks are more universally eaten than is generally known. As an instance of this, a 

 letter from Mr. Vinal N. Edwards, of Woods Hole, Mass., states that the trap fishermen 

 of that region ship all of the large species of sharks, with one exception, caught in their 

 traps. Among those shipped are the thresher {Vulpccula marina), dusky sharks {Car- 

 charhinus obscurus and milberti), and the black-finned shark {Carcltarhinus Hmbatus), 

 the exception being the sand shark (Carcharias taurus). The fishermen remove the 

 head, fins, and tail; the body then looks not unlike a swordfish and is shipped to Boston 

 or New York, where it is sold as deep-water swordfish. The fishermen receive from 

 3 to 8 cents per pound for this class of food. 



There are still other uses to which the sharks and rays might be put. For example, 

 oil may be extracted from the liver, which reaches a very large size in these forms; the 

 skins, which have been used to a limited extent, possess certain characteristics which, 

 it would seem, might be capable of more general use. Stevenson (Report of the United 

 States Commission of Fish and Fisheries for 1902, p. 347-348) says: 



The skins of sharks, rays, and dogfish are commonly very rough and studded with numerous homy 

 tuberculous markings or protuberances. Some have small imbricated and triangular scalelikc tubercles; 

 otliers imimbricated and nearly rhomboid, which in one species are ranged near each other in quin- 

 cunxes, or they may be quite square, compact, and comparatively smooth on top. These protuberances 

 are usually firmly fixed to the skin so that tliey are not easily separated therefrom. They are rough 

 and hard and take a polish almost equal to stone. 



These skins, like tliose of all cartilaginous fishes, are ver>- durable. A peculiarit)', in addition 

 to the markings above noted, is the nonporous character. The pores that are everywhere present in 

 the skins of most mammals, which give tlie natural grain in the tanned leather, are entirely indiscern- 

 ible in the skins of these fish. The result is to render tliem almost proof against water absorption. 

 Although by skillful tanning the fibers of seal and other skins may be plumped and the body of the 

 membrane solidified, yet much water exposure loosens die fiber and gradually permits absorption. 

 Not being of a porous nature, shark skin is naturally free from this defect; but the advantage is also 

 a disadvantage in some respects. The nonporous leather is practically airproof as well as waterproof, 

 and that is a serious defect when its use for footwear is considered. Beyond this, tlie skins of sharks 

 and similar fishes may be prepared into a verj' durable, uoncrackiiig leather, for which many uses may 

 be found. 



