Government financial supports would be neces- 

 sary; in the third instance. Government support 

 of research leading to market demand would 

 be followed by a self-supporting commercial 

 enterprise. 



In either a bounty or a vessel-charter sys- 

 tem. Governmental payment to the fishermen 

 would be necessary. To attract sufficient 

 fishermen to effect the desired mortality, 

 these payments would have to be, roughly, 2 

 to 3 cents a pound for whole fish or 17 to 25 

 cents a pound for liver, or between $1. and 

 $3. million in the first year. 



The same amounts of money, applied to a 

 developmental research program, would go far 

 toward developing uses for dogfish or dogfish 

 products that would lead to a market demand 

 for the dogfish. This, in turn, would make 

 possible a self-sustaining fishery that would 

 serve to keep the stocks at the desired low 

 levels without further necessity for Govern- 

 mental supports. Development of market de-- 

 mands, therefore, seems a logical and 

 promising first step in dogfish control. 



REPELLING AND DETERRING 

 DOGFISH 



Considerable time and effort have been 

 spent on attempts to develop effective chemical 

 substances that would repel or deter sharks. 

 But little information of use to commercial 

 fishermen has resulted. Repellent dye mate- 

 rial (including nigrosin), used to some extent 

 by the Armed Forces, is too expensive for 

 use with large nets, and too much of the 

 material is required for it to be economically 

 used even if the price could be lowered appre- 

 ciably. Then, too, other factors associated 

 with fishing — such as the commotion created 

 by fish in the net, substances secreted or 

 excreted by the fish, and possibly other 

 factors — may negate the effects of repellents 

 by serving as more powerful attractants. Re- 

 cent studies reported through the shark re- 

 search panel of the American Institute of 

 Biological Sciences have indicated that, for 

 limited application, it may be possible to 

 develop a chemical repellent or deterrent, 

 but at present there is no substance known 



that will provide practical protection against 

 shark damage under all conditions. 



Mechanical deterrents, including protective 

 poultry- wire covers on trawl cod ends, double- 

 twine nets, and other devices, have been used 

 with some success. Another lead that might 

 result in some decrease in shark damage 

 involves the ultimate use of repellent elec- 

 trical fields about the net. Electricity is 

 selective in its action. As experiments with 

 electrical fishing gear have demonstrated, 

 the voltage used can be regulated so that 

 larger fish can be dealt stunning doses whereas 

 smaller fish can swim unharmed and even be 

 attracted to the electrode. Perhaps, at some 

 future date, a series of electrodes can be 

 set up to protect both moving and stationary 

 nets against sharks. Unfortunately, dogfish 

 are relatively small sharks, and the differences 

 between their size and the sizes of the fish 

 being sought might not be sufficient to allow 

 the selective action of the electrical fields 

 to be effective. 



This is the proper place to stress that de- 

 velopment of an effective control program — 

 one seeking to reduce numbers of sharks or 

 one seeking merely to repel or deter sharks — 

 is dependent on a much more thorough knowl- 

 edge of basic shark biology than we now 

 possess.' 



POSSIBILITIES FOR DOGFISH 



UTILIZATION: CHARACTERISTICS 



AND PROPERTIES OF DOGFISH 



OILS AND PROTEINS 



Oil and protein are the two principal com- 

 ponents of dogfish that might be used com- 

 mercially. Only if processing plants and 

 markets for both oil and protein were available 

 would a commercial dogfish fishery be profit- 

 able — and, therefore, self-sustaining. 



Moreover, in view of the competition that 

 would be faced by the usual dogfish oil and 

 protein products on the market, uses unique 

 to dogfish products are extremely important. 

 If uses found for dogfish products could be 



' Much of the material in this paper has been taken 

 from a manuscript by Springer and Gilbert. 



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