40 UNUTILIZED FISHES. 



METHODS OF CONTROLLING DESTRUCTIVENESS OF DOGFISH. 



The study of the food of the eight fishes just considered shows that 

 the smooth dogfish {Musteliis canis), the sandshark {Carcharias 

 littoralis), and the horned dogfish {Squalus acanthias) are very 

 destructive to our fishing industries. The two dogfishes are by far 

 the most harmfuL The smooth dogfish, as has been shown, destroys 

 lobsters by the hundred thousand, and the horned dogfish destroys 

 mackerel, herring, etc., by the millions, besides injuring nets, trawls, 

 and other fishing gear to the extent of thousands of dollars' worth 

 each year. Fishermen all along our coast are seeking means to be 

 rid of these pests. It is quite evident that the time has come to con- 

 sider carefully this serious condition and to provide some means of 

 controlling, the devastation. 



INADEQUATE SUGGESTIONS. 



Prince (1904) considers the reduction of the numbers of dogfish 

 to be no easy matter and their total extermination jDractically im- 

 possible. He lists the suggestions offered to the Canadian govern- 

 ment for reducing the numbers of horned dogfish as follows: 



(1) Liberate alive some hundreds of dogfish, having securely fastened outside 

 their bodies (by means of hooks, wires, etc.) glittering and gaudy streamers or 

 jingling chains or bells, calculated to terrify and frighten away the schools of 

 dogfish, on the old principle of setting at liberty a rat with a bell hung to its 

 neck. 



(2) Iiioculati' a number of dogfish witli some fatal or contagious disease, 

 thus securing the infection and death of all the schools of dogfish which may 

 hover near, on the principle ado])ted in reducing the pest of rabbits in Australia 

 some years ago. 



(3) Dynamite the great schools of dogfish when they appear. 



(■4) Employ government cruisers and their men in capturing these pests or 

 let the government employ special vessels for the purpose until the plague is 

 reduced. 



(5) ray a bounty of 1 cent for every 5 tails (.f;:: per 1,000) * * *. 



(6) Pay a bounty on basis of the weight of the dogfish captured, say, so 

 much per loO pounds * * * Thus the suggested rates range from 10 to 15 

 cents per 100 pounds to 2.5 cents per 100 pounds. 



(7) Pay a bounty on the total yield of oil, a fixed rate on each gallon of oil 

 produced by a factory being guaranteed to a firm or company carrying on reduc- 

 tion works. 



(8) Use of long seines of strong cord. 1,000 yards or more in length, under 

 departmental direction, and surround the schools as is done with the schools of 

 sharks in India. 



Most of the above methods are inadequate for solution of the prob- 

 lem. Dr. Prince pointed out that the first three in the list would 

 as likely prove harmful to valuable fishes as to the pest. Methods 4, 

 5, 6, and 8 would involve unnecessary expense. There is a natural 

 tendency to jump at the conclusion that a bounty is the only way to 



