182 Conservation Department 



Economics of the Sea Lamprey. — On the good or credit side 

 the sea lampreys always spawn in fresh water, and on their way 

 from the ocean to the spawning grounds are in excellent condi- 

 tion. They take no food on this migration, and therefore do not 

 injure the fishes in the rivers and streams where they spawn. On 

 the other hand they make wholesome food for human beings; and 

 their young, the mud-eels or sand-lampreys make good bait. After 

 laying their eggs, the sea lampreys die and never return to the 

 ocean. Hence, in the river fisheries of New York, the sea lamprey 

 is not injurious but beneficial. In New England, they were much 

 sought after, and were caught by the barrel, and salted down for 

 future use. The farmers away from the rivers, according to Goode,* 

 would trade a barrel of pork for a barrel of lampreys. 



In Alaska, the Indians look forward to the annual migrations of 

 the Pacific lampreys (Entosphenus) up their rivers and collect 

 large numbers of them to supply food for their dogs as well as 

 for themselves. By personal experience it is known that lampreys 

 are good food when in full vigor on their way to spawn. 



The bad or debit side of the sea lamprey is comprised wholly in 

 its predatory or parasitic life, and this is practically all spent 

 in the ocean. The transformed young in the streams leading to 

 the sea might attack river fish for a meal or two, but they are 

 very small and the injury to the inland fisheries is therefore 

 negligible. On the other hand no doubt many of these transformed 

 ones on their way down the river are snapped up by the river 

 fish and are themselves turned into food. 



Once in the ocean, those which survive must increase 35 to 55 

 times in length and 95 to 135 times (Fig. 7) in weight before they 

 are ready to migrate up the streams where they were born to start 

 a new generation. This means an enormous amount of food, for 

 in addition to the increase in weight there must be a much larger 

 amount of food taken to keep them alive, and furnish energy for 

 hunting their prey. 



The fishes known to be fed upon by the lampreys in the sea, 

 as given by Goode x and Bigelow, 2 are : cod, haddock, mackerel, 

 shad, sturgeon, salmon and even the basking shark. 



Economics of the Lake Lamprey. — Unlike the sea lamprey, 

 the lake lamprey passes its entire life cycle in fresh water. All 

 its predatory life is in the lakes of the State, and therefore its 



* Goode, G. Brown. The fisheries and fishery industries of the United 

 States. Section 1, Natural History of useful aquatic animals. Lampreys, 

 pp. 677-681, Washington Government Printing Office, 1884. 



1 Loc. cit. 



2 Bigelow, H. B. Fishes of the Gulf of Maine. Bull. Bur. of Fisheries. 

 Vol. 40, part 1, p. 19, 1924. 



