As Its larval period terminates, the lamprey, now six to eight 

 inches long, changes into the adult form. The eye6 become more highly 

 developed; the mouth becomes circular, and in it appear the file-like 

 tongue and the sharp, horny teeth. In its mouth develop buccal glands 

 which secrete. a substance that prevents the blood of its victims from 

 coagulate ng.-£/ The transformed lamprey nov leaves the stream bank and 

 migrates downstream to the lakes or the ocean. There it begins feeding 

 upon the blood and body fluids of fish, its sole nourishment. 



A vigorous swimmer, this predator attaches itself to almost any 

 part of a fish. A position under the pectoral fin seems to be preferred. 

 The victim, unable to free itself, continues to swim about. The strong, 

 horny teeth of the lamprey, assisted by the rasping tongue, soon pene- ;, . 

 trate the fish scales and flesh. Feeding stops when the host is dead or t 

 the lamprey becomes glutted. A small fish frequently is killed; a large 

 one, if it escapes, is scarred so badly that it is unmarketable. 



The length of the adult predaceous stage before the lamprey 

 becomes sexually mature is unknown. Several biologists estimate it to 

 be from one and a half to three and a half years. ** Adult life in the 

 lakes is thought to be two years. The life cycle lasts at least five 

 years and may extend to eight »=J 



These pests have a very limited value, although in many Euro- 

 pean countries they are highly esteemed as human food. Unsuccessful 

 attempts have been made in this country to make lampreys palatable to 

 Americans. Because of softness of body and extreme susceptibility to 

 fungus infection cooking tests failed. Analyses indicate that Vitamin 

 A potency and oil yield of the Great Lakes sea lamprey are much too low 

 for commercial exploitation. Biological supply houses require a small 

 number. 



Lampreys have an unlimited liability potential. In the ocean, 

 they attack cod, haddock, mackerel, menhaden, salmon, shad, and sturgeon; 

 often scar swordfish; and even fasten onto sharks. In the Great Lakes, 

 they have contributed to depletion of lake trout, and are attacking carp, 

 herring, smallmouth bass, suckers, whitefish, and yellow pike-perch, and 

 almost all other species there. 



These predators have no known natural enemies. Their existence 

 in the St. Lawrence River and in Lake Ontario from early times shows they 

 are adapted to a fresh- water life. Because of the barrier of Niagara 

 Falls they did not have access to the other Great Lakes until construc- 

 tion of the Welland Canal provided a detour, thus enabling the sea lampreys 

 to make a successful invasion. 



hj Vernon C. Applegate, The Menace of the Sea Lamprey, supra. 



*J Simon Henry Gage, The Lampreys of New York State — Life History and 

 Zc onomi c s • supra • 



6/ Vernon C. Applegate, The Menace of the Sea Lamprey, supra. 



705-2 



WHSE 00572 



