20 BULLETIN OF THE BUREAU OF FISHERIES 



sexual maturity run up from the lakes into small clear brooks to spawn in June. 

 As they ripen, the two sexes become dissimilar in appearance, the males (and this 

 is equally true of sea-run fish both in American and European rivers) developing a 

 ridge along the back, the females a finlike crest between the vent and the caudal fin. 

 They build nests of round stones, which they drag together with their suckerlike 

 mouths, as has often been described and pictured in natural histories, and after 

 spawning apparently most, if not all, die, for not only have they often been found 

 dead but their intestines atrophy, they are attacked by fungus, and they become so 

 debilitated that recovery seems out of the question. In short, the old tradition 

 that no lampreys return to the sea from the rivers they ascend seems well founded. 



The larvae are very different in appearance from the adults. They are blind 

 and toothless, with mouths and fins of different shape. They continue in this 

 state for a period estimated at 3 to 4 years, during most of which time they live in 

 holes or burrow in the mud or sand, hiding under stones. Doctor Huntsman informs 

 us, however, that they have been taken in tow nets in the Shubenacadie River in 

 Nova Scotia. They subsist on minute organisms. At the end of this larval period, 

 when they have grown to a length of 4 to 6 inches, they undergo transformation to 

 the adult form and structure, an event occupying about two months — August to 

 October — and descend the streams of their nativity to the sea just before the water 

 freezes in November or December, to live and grow there for one or two years or 

 until they reach full size and sexual maturity. The larva? of the sea lamprey are 

 very abundant in the mud of flats near the mouths of small tributary streams of such 

 river systems as the Delaware and Susquehanna, where lampreys breed abundantly, 

 and they have been reported in the Shubenacadie (a stream emptying into the Bay 

 of Fundy) and no doubt occur in the Merrimac and other Gulf of Maine streams. 



Although lampreys spawn but once and then perish, their period of growth is so 

 long that large ones, not yet mature, are to be found in salt water all the year round. 



Little is known of the habits of the lampreys while they hve in the sea further 

 than that the mode of life centers around a carnivorous nature. Judging from 

 their landlocked relatives and from the occasions on which they have been found 

 fastened to sea fish, they must be extremely destructive to the latter, which they 

 attack by " sucking on " with their wonderfully effective mouths. Usually the lam- 

 prey fastens to the side of its victim, where it rasps away until it tears through the 

 skin or scales and is able to suck the blood. Its prey sucked dry, it abandons it 

 for another. Probably lampreys are parasites and bloodsuckers, pure and simple, 

 for we can not learn that anything but blood has been found in their stomachs, 

 except fish eggs, of which lampreys are occasionally full. 12 Lampreys have been 

 found preying upon cod, haddock, and mackerel in Massachusetts Bay, even on 

 basking sharks, and salmon, too, are said to be much annoyed by them. When 

 not clinging to anything they are strong, vigorous swimmers, progressing by an 

 undulating motion in the horizontal plane, and they are said to be exceedingly 

 aggressive in their attacks on other fishes. Occasionally they are found fast to 

 driftwood, even to boats. 



" " The Fisheries and Fishery Industries of the United States," by George Brown Goode. Section I, 1884, p. 677. Wash- 

 ington. 



