The Lake and Brook Lampreys of New York 457 



ECONOMICS. 



From the human stand-point, beneficial or injurious, as ap- 

 plied to an animal or plant relates solely to the supposed ad- 

 vantage or disadvantage to the human race that it subserves. 

 No doubt from the economical stand-point of the animal or 

 plant, judge and prisoner would change places. In this eco- 

 nomical consideration two questions arise : First, in what 

 way does this animal or plant subserve man in supplying food 

 or clothing and secondly, does it destro}^ for its own use, food 

 or clothing that might otherwise be utilized hy man. 



To answer these two simple questions it is only necessary 

 to find out the food of an animal, and also the animals for 

 which it in turn serves as food. 



Food and Uses of the Larva. — The food of the larva consists 

 of microscopic organisms separated in some way from the 

 constant stream of water drawn into the combined oesophageal 

 and branchial chamber. It thus appears that in its larval life 

 the lamprey is not injurious to man by destroying food that 

 he wishes, directly or indirectly, to utilize for his own benefit. 

 On the other hand, from the tenacity with which the larvae 

 retain life they have been found excellent bait for all kinds of 

 ordinary carnivorous fishes. The fishermen along the Cayuga 

 and Seneca Lake inlets make considerable use of the larvae 

 for bait ; this form of bait has not up to the present been much 

 used in the lake fisheries, as apparently its excellence is un- 

 known. At Ovvego, on the Susquehanna River, however, 

 quite a business is carried on in supplying larval lampreys to 

 fishermen of all kinds, and many are shipped to distant points. 



As no distinction is yet known between the larvae of the 

 brook and of the lake or sea lamprey, all larvse may be classed 

 as non-injurious and as positively beneficial by serving for 

 bait, and thus in aiding man to obtain food fishes. 



Economics of the Adults. — Unlike the larva the adult lam- 

 prey is largely or wholly parasitic, and in obtaining its food 

 destroys or injures the fishes used by man as food. It is 

 stated by Giinther ('53, p. 133), that the food of the lamprey 

 (/*. marinus and P. fliiviatilis) consists of worms and insects, 



