18 



UNUTILIZED i'lSHES. 



ESTIMATE OF DESTRUCTIVENESS. 



The foregoing figures shoAv that the food of the sand shark consists 

 ahiidst entirely of fish. No lobster, crab, or other crustacean was 

 found in any of the stomachs, which fact is at variance with the 

 report of Verrill and Smith, who state that the sand shark feeds 

 extensively on these forms. My observations accord more closely 

 with Dr. Linton's. It should be taken into account, however, that 

 the sharks examined were taken from unnatural surroundings, 

 namely, the traps, Avhere they were held in close quarters with most 

 of the species of fish found within them. But, taking the data as 

 collected, and estimating the number of sand sharks in the vicinity 

 where these were taken (Buzzards Bay and Vineyard Sound) at only 

 25,000, and allowing to each sand shark four fish per Aveek, a most 

 conservatiA^e estimate, the numbers eaten by sand sharks in one month 

 Avould be as folloAvs: 



Estimate op Fish Destroveo ICach Month hv 25,000 8ani) Sharks in Buzzards 

 Bay and Vineyard Sound. 



Number 

 Species. de- 



stroyed. 



Menlmden ( Brevoortia tyrannus) ' 167, COO 



Alewife ( Pomolobtis psetidoharengus) I 30, 280 



Flounder ( Paralichthys dentatus) 24, 240 



Soup (Stenotomus chri/sops) 18, 160 



Species. 



Butterfisli (Poronotn," triacanthus) 

 Bonito (Sarda aardn ) 



Total 



Number 



de- 

 stroyed. 



18, 160 

 12, 120 



270, 560 



The sand shark is to be characterized as a fish Avhich is destructive 

 to fishes of food or other commercial A'^alue, although not nearly so 

 destructive as the horned dogfish, Avhich Avill be considered next. 



THE HORNED DOGFISH. 

 GENERAL APPEARANCE AND HABITS. 



In general appearance the horned dogfish {Squalns acanthias) very 

 much resembles the smooth dogfish. It has the same slender, elon- 

 gate body covered with numerous sharp tubercles (placoid scales), 

 the A^entrally placed mouth and nostrils, and the characteristic spira- 

 cles. The color is slaty aboA'e, Avith a line of Avhitish spots extending 

 along either side of the back. The under portions fade out almost 

 to white. The horned dogfish is to be distinguished from the smooth 

 dogfish by its small sharp teeth and a rather high dorsal spine in 

 front of each of the two dorsal fins. In length the adults A^ary from 

 2 to 3 feet and in weight from 5 to 15 pounds. They are strong, 

 actiA^e SAvimmers, and roam about the shoals and deeper Avaters in 

 great schools, pursuing their prey like a pack of Avolves. The name 



