the fall, no doubt representing periods when they 

 were locally abundant during their migrations. 

 The industrial fishery fleet at Gloucester caught 

 quantities of dogfish off Cape Ann, Mass., on 

 Stellwagen Bank, and off Nauset, Mass., although 

 the volume landed represented only from 1.5 to 

 3 percent of the total pounds landed (Edwards, 

 1958b). 



Reduction plants do not like to process large 

 amounts of spiny dogfish because they yield only 

 meal, with very little oil, and there are serious 

 mechanical problems involved in handling the 

 species. The rough skin of the dogfish causes 

 these fish to jam conveyor belts, and to pack in 

 bins and chutes. The collagen in the carcasses 

 clogs screens (Tarr, 1958). Tarr also states that 

 the dogfish result in a poor yield of meal com- 

 pared to other fishes. 



Change in the design of processing machinery 

 is suggested as one way to overcome the problems 

 in handling dogfish carcasses. For example, in- 

 stallation of grinders designed specifically for 

 dogfish may solve the jamming problem, but fur- 

 ther technological research is needed before dog- 

 fish carcasses can profitably be used (Alverson 

 and Stansby, 1963). 



The rapidly expanding pet-food industry has 

 been suggested as a potential user of great quanti- 

 ties of dogfish. Jones (1959) reports that on the 

 Pacific coast the estimated potential annual pro- 

 duction of dogfish for dog and cat food is on the 

 order of 60 to 80 million pounds. 



FOOD USES 



A vast protein food resource is wasted each year 

 in the 'United States because only infinitely small 

 amounts of spiny dogfish are used for human food. 

 Under present economic conditions, however, and 

 because of prejudice toward eating shark flesh, it 

 probably would be most unprofitable to fish and 

 market dogfish for human food. 



The repugnance (and perhaps fear) that most 

 people feel towards sharks in particular does not 

 help to make dogfish popular as a food fish. The 

 rery name "dogfish" connotes something not suit- 

 able for humans. Efforts to disguise the species 

 under a euphemism have included simply not 

 mentioning what it was. Thus, Field (1907) re- 

 ports it was served as "fish" on two occasions in 

 the Marine Biological Laboratory (Woods Hole) 



mess hall and enthusiastically accepted by the un- 

 suspecting diners. It has been served experi- 

 mentally in hotels and listed on the menu as "Jap- 

 anese halibut." In England, dogfish are gutted, 

 skinned, beheaded, and marketed as "flake" and 

 "rock salmon" and are widely used as one of the 

 ingredients in the popular carryout dish, fish-and- 

 chips. 



In the United States during World War I, a 

 great effort was made to popularize a number of 

 relatively unexploited fishes to increase their ac- 

 ceptance by the consumer and thus relieve the 

 war-induced meat shortage. Spiny dogfish was 

 one such fish, and it was dubbed "grayfish," the 

 name by which it is marketed today. A 14-ounce 

 can of grayfish sold retail for 10 cents, and a 

 Government circular (U.S. Bureau of Fisheries, 

 1916) was published in which 17 different recipes 

 for preparing grayfish were listed. 



Canned grayfish did not prove to be a practical 

 solution to the problem of dogfish utilization. 

 Corrosion of the cans, caused by changes in the 

 chemistry of the meat, and the offensive ammonia 

 smell that developed caused the buying public to 

 reject the product. The flesh of dogfish, as with 

 other elasmobranchs, contains large amounts of 

 urea, which rapidly decomposes to form ammonia 

 (Mavor, 1921). Fresh and frozen dogfish tissue 

 contain about the same amounts of urea (0.9- 

 1.5 percent), and hydrolysis, with the subse- 

 quent release of ammonia, occurs in the frozen 

 flesh (Benson, 1924). Moyer, Southcott, Baker, 

 and Tarr (1959) tested several methods of storing 

 fresh dogfish flesh for periods up to 21 days. The 

 storage included in ice and in refrigerated sea 

 water, with and without added antibiotics (chlo- 

 rotetracycline). They concluded, ". . . dogfish, 

 when stored under nearly ideal conditions, appear 

 to spoil no more rapidly than most other sea fish." 

 It seems obvious though that dogfish is best eaten 

 when very fresh. 



The keeping quality of dressed dogfish was fur- 

 ther studied by Southcott, Moyer, Baker, and Tarr 

 (1960). The fish were stored in individual poly- 

 ethylene bags at 0°, 5°, and 10° C, with a control 

 lot unbagged in crushed ice. The experiment 

 lasted 21 days. Each day two fillets were cut from 

 a single fish from each treatment and used for 

 bacteriological and chemical determinations. 

 The authors found that, "Less ammonia and 



548 



U.S. FISH AND WILDLIFE SERVICE 



