FISHES OF THE GULF OF MAINE 



13 



in American rivers, average 2 to 2% feet long, 

 up to a maximum of about 3 feet. One of 33 

 inches weighed 2% pounds. 



Habits. — It has been known from early times 

 that the sea lamprey breeds in fresh water. How- 

 ever, it does not enter all the streams within its 

 range indiscriminately. As an illustration, we 

 may cite outer Nova Scotia and the Bay of Fundy, 

 where lampreys run in the St. Marys, Sackville, 

 Annapolis, Shubenacadie, Petit Codiac, and St. 

 Johns Rivers, but not in the Moser or Apple 

 Eivers, although these last also are "salmon" 

 rivers. Their requirements are a gravelly bottom 

 in rapid water for their spawning beds, with muddy 

 or sandy bottom in quiet water nearby, for the 

 larvae. 



In many small streams, and in larger ones if 

 these are blocked by dams or high falls, they may 

 spawn only a short distance upstream ; even within 

 the influence of the tide, although invariably in 

 fresh water. But they are able to ascend falls, 

 if these are not too steep and high, by clinging 

 to the rocks by their oral discs and resting. And 

 they may run upstream for very long distances in 

 large rivers, as they did formerly in the Merrimac 

 and probably still do in the St. Johns River. They 

 are still to be found 200 miles or more from the sea 

 in the upper tributaries of the Delaware and Sus- 

 quehanna systems. 



Since the breeding activities of the sea lamprey 

 take place in fresh water, a brief account will 

 suffice here. As the two sexes ripen, the males 

 develop a strong ridge along the back, the females 

 a crestlike fin between the anus and the caudal 

 fin. Spawning, commencing when the tempera- 

 ture of the water is about 50° F. (10° C.) is com- 

 pleted by the time it has warmed to about 68°-70° 

 (20°-21° C), and a sea lamprey has been found 

 to contain 236,000 ova. Working in pairs, some- 

 times with a second female assisting, they make 

 depressions 2 to 3 feet in diameter and about 6 

 inches deep in the stream bed in stretches where 

 the bottom is stony or pebbly, dragging the stones 

 downstream in a pile with their suckerlike 

 mouths. And they are able to move stones as 

 large as one's fist. It is in these depressions that 

 the eggs are deposited, not among the piles of 

 discarded stones that have often been described 

 as "nests." It seems that they all die after spawn- 

 ing; 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. 



The larvae are different in appearance from the 

 adults: blind, toothless, with mouths and fins of 

 different shape. They continue in this state for 

 a period estimated as 3 to 4 years, during most of 

 which time they live in burrows in the mud or 

 sand, or hide under stones. They are abundant 

 in the mud of flats near the mouths of small 

 tributary streams of river systems such as the 

 Delaware and Susquehanna, where lampreys still 

 breed in large numbers, and 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 September or October. They 

 run down to the sea in November or December, to 

 live and grow there for one or two years, so 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 live in the sea further than that their 

 mode of life centers around a fiercely predaceous 

 nature. Judging from their land-locked 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. The lamprey usually 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 cannot learn 

 that anything but blood has been found in their 

 stomachs, except fish eggs, of which lampreys are 

 occasionally full. 20 



In salt water they have been found preying on 

 mackerel, the various anadromous herrings, cod, 

 haddock, American pollock (Pollachius) , salmon, 

 basking sharks, swordfish, hake (Urophycis), 

 sturgeons and eels. Sometimes as many as three 

 or four are fast at one time to a single shad, and 

 they are said to be exceedingly aggressive in 

 their attacks on other fishes. Occasionally they 

 are found fast to driftwood, even to boats. When 

 not clinging to anything they are strong, vigorous 

 swimmers, progressing by an undulating motion. 



» Ooode, Fish. Ind. U. S., Sect. 1, 1884, p. 677. 



