50 Memoir Sears Foundation for Marine Research 



states as early as the end of March or early April. In the rivers tributary to the Gulf of 

 Maine the runs are at their maximum peak during May and early June. Few, if any, enter 

 the rivers after that. In New Jersey and Pennsylvania the peak is from late April through 

 May. Precise seasonal data are lacking for rivers farther south or farther north.°' In many 

 small streams, and in larger ones also, if their passage is blocked by dams or falls, they may 

 spawn only a very short distance upstream, even within the influence of the tide, although 

 invariably in fresh water. They are able to ascend falls, if not too high and steep, by cling- 

 ing to the rocks with their oral discs and resting, but they do not leap as salmon do in similar 

 circumstances. They may run up for long distances in large rivers. Such, for instance, was 

 formerly their habit in the Merrimack and Hudson River drainage systems, while in the 

 upper tributaries of the Delaware and Susquehanna systems they are still to be found 200 

 miles or more from the sea, and 1 50 miles upstream in the Savannah River system. 



Since the breeding activities of the Sea Lamprey take place in fresh water, a brief 

 account will suffice here. As the two sexes ripen they become dissimilar in appearance, the 

 males developing a strong ridge along the back, the females a fin-like crest between the 

 anus and the caudal fin (p. 46). Analogy with the landlocked form, and dates actually 

 recorded, suggest that spawning is commenced when the temperature is about 10° C. and 

 is completed by the time the water has warmed to about 20 to 2 1 ° C. 



Spawning takes place in stretches of the stream where the bottom is stony or pebbly. 

 Working in pairs, a male and a female, with a second female sometimes assisting, make 

 depressions two to three feet in diameter and about six inches deep in the bed of the stream 

 by dragging away the stones by means of their oral discs, leaving the stones in a pile down- 

 stream. 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 de- 

 scribed as "nests.""* To quote from Regan:'" 



The female now secures herself by means of her sucker to some large stone near the upper 

 end of the nest, and her mate attaches himself to her in the same way near her head, and 

 winds himself partly round her; then the two together stir up the sand with vigorous move- 

 ments whilst the eggs and milt are simultaneously deposited. The eggs are covered with an 

 adhesive substance, and particles of sand stick to them, so that they sink to the bottom of the 

 nest. The pair now separate and at once commence removing stones from above the nest and 

 enlarging the pile at the lower end, the sand thus loosened being carried down and covering 

 all the eggs. The process is repeated at short intervals until the spawning is completed. . . . 



After spawning, it seems that the parents die, for not only have they been found dead 



67. The landlocked form commences to "run" when the temperature has warmed to about 7 to 9° C. (Surface, 4th 

 Rep. For. Comm. N. Y., 1899: 227). 



68. Bigelow and Welsh (Bull. U.S. Bur. Fish., 40 [i], 1925 : 20) fell into this same error. For an excellent account 

 of the nesting and spawning of the Sea Lamprey, see Hussakoff (Amer. Nat., ^6, 1912: 729) ; for the land- 

 locked form, see Surface (4th Rep. For. Comm. N. Y., 1899; 191), Coventry (Publ. Ont. Fish. Res. Lab., Biol. 

 Ser. No. 20, 1922) and especially Gage (Sci. Mon., N. Y., 2^, 1929: 401). 



6g. Regan (Fresh Water Fish. Brit. Isles, 1911: 6), based on accounts of the American landlocked form. 



