The Sharks— Part Tivo 351 



their livers. Since 1956, Canada has been trying to eradicate Spiny dogfish 

 from British Columbia waters. About $140,000 a year is spent on bounty 

 payments of 12 cents a pound for dogfish livers, which are delivered 

 to oil plants where the liver oil is rendered in an attempt to get back some 

 of the money allotted to the bounty program. These marauders are 

 cursed by Pacific coast fishermen from Southern California to Alaska. 



In 1938, a campaign was launched to reduce the Spiny dogfish pop- 

 ulation in Placentia Bay, near St. John's, Newfoundland. About 10,391,- 

 000 pounds of Spiny dogfish— some two to three million of them— were 

 caught, but a government report on the dogfish drive said that the 

 catching of these millions of dogfish did not result in "any apparent 

 diminution of the supply." 



When packs of these voracious sharks invade a fishing ground, virtu- 

 ally no other kind of fish can be caught. A long-line with 700 hooks 

 strung along it was once set off Cape Breton, Nova Scotia. When the 

 long line was hauled up, 690 hooks had Spiny dogfish on them. This 

 abundant shark is probably the most prolific shark in the sea. Twenty- 

 seven million Spiny dogfish were taken in one season off the coast of 

 Massachusetts alone; 20,000 were once caught in a single haul off the 

 Cornwall coast of England; Long Island fishermen used to measure 

 their catch of Spiny dogfish in wagonloads. When their abundance is at 

 its peak, an average trawler can take in 6,000 to 8,000 of them in a day. 

 Years ago, dogfish were dried, stacked, and burned as fuel by Cape 

 Codders, who found the dogfish far more plentiful than the local trees. 



After gorging on the fisherman's hard-won catch and then tearing 

 his valuable nets, the Spiny dogfish has a coup de grace for the fisher- 

 man who carelessly reaches into the tattered net to grab the vandal. 

 The Spiny dogfish's weapons are the dorsal spines or quills (remember 

 the ichthyodorulites? ) which the little shark brings into play by curling 

 its body into a bow, exposing the length of the spines, and then lunging 

 forward. The spine— which is slightly poisonous— can inflict a painful 

 injury. Fishermen have been laid up for several days after being stabbed 

 by a Spiny dogfish. The shark is amazingly accurate with its unusual 

 weapon, which is used only in defense. If you put a finger lightly 

 on its head, it will immediately bend into a bow and strike so skillfully 

 that the spine of its back dorsal will prick your finger, but not even 

 scratch its own skin. (Dr. H. Muir Evans, a British physician who has 

 made a study of venomous apparatus of fishes, sav^s ichthyodorulites 

 he has examined are structurally similar to the poisonous spines still 

 borne by several modern species of sharks and rays.) 



The alternating dark and light rings on the second dorsal spine have 

 been used to determine the age of Spiny dogfish. The rings result from 

 periods of fast growth during the summer months (light rings) and peri- 



