168 Conservation Department 



Just as soon as a batch of egg's is laid the lampreys commence 

 to jerk the stones from the edge of the nest. That seemed puzzling 

 at first, but on watching further it was found that while many 

 eggs were visible immediately after they were laid, they were 

 soon all covered up by the sand washed down when the stones 

 were loosened at the edge. It is of great advantage to have the 

 eggs buried in the sand for they do not stick tightly to the sand 

 particles very long. Soon they are quite free among the sand 

 grains, and might be washed downstream if not covered. 



If one examines a lamprey in the early part of the egg-laying 

 time, only a limited number of the eggs will be found free in the 

 abdominal cavity, all of the others will be imbedded in the ovary. 

 As stated above, they ripen from behind forward, so that the last 

 eggs to be laid are from the cephalic or front end of the ovary. 

 This explains, too, why the eggs are laid in batches. After one 

 lot is laid the lamprey works at the nest to get those well covered 

 with sand, and then by some means, she knows when another batch 

 is ready and proceeds to lay them, and so on till all are laid. 

 From my own and the published observations of others, the egg- 

 laying at its height recurs frequently, sometimes every two to 

 five minutes with the brook lamprey, but the intervals may be 

 much longer. Apparently it requires only a day or two for all 

 the eggs to be laid, but the lamprey remains around the nest for 

 several days, and spends much time and effort in moving stones 

 around the edge of the nest, and thereby loosening the sand and 

 gravel which washes down and covers the eggs securely. 



With the lake lamprey in one especially favorable case where 

 the egg-laying was at its height the pair of lampreys "shook 

 together" 5 times and at 5, 10 and 15 minute intervals. With the 

 sea lamprey the egg-laying as described by Hussakof* is fully 

 as rapid as with the lake lamprey. It sometimes happens when 

 there are several lampreys in a nest that the males attack each 

 other. Then there is a lively scrap. One male grabs another by 

 the back or in almost any place and jerks him out of the nest. 

 They writhe and struggle in the stream making a great splashing. 

 This explains in part at least why there are lamprey marks on the 

 males. Other authors have commented on the attachment of male 

 brook lampreys and their leaving the nest together. With the 

 lake lampreys as described above, there is no doubt of the un- 

 friendliness of the encounter. 



Number of Eggs Laid by Different Lampreys.— The number 

 laid by the different kinds is roughly in proportion to their size. 



In round numbers thev have been found as follows: 



Sea lamprey 236,000 



Lake lamprey 108,000 



Brook lamprey 3,000 



In determining the number of eggs the female is selected at the 

 beginning of the spawning season on the way to the spawning 



* Loc. cit. 



