200 REPORT OF THE COMMISSIONERS OF 



spawning bed, without the presence of a male. They commence to spawn shortly 

 after the water reaches a temperature of forty degrees Fahrenheit for the average of 

 the day, which is generally about May i, although we have found them upon their 

 beds as early as April 18.* If the weather keeps warm, in a few days thousands of 

 them will be found on their little spawning beds, extending in general over the range 

 of the stream that is to be occupied later by the lampreys of the larger species. They 

 remain on their spawning beds about two weeks, more or less, depending upon 

 temperature; the warmer it is, the shorter the duration of the spawning period. They 

 then become covered with fungus, drift down stream and are either eaten by 

 carnivorous birds and mammals, or die and settle in the depths of the quiet pools and 

 are covered with debris (see illustration No. 13). In such places we have often found 

 their remains. 



The bitterns (Botaurus lentiginosus) and smaller herons (Ardea viresccns) are 

 especially abundant in the stream during the spawning time of these lampreys and 

 are their particular enemies. (See further discussion of this subject under the heading 

 "Lake Lamprey.") 



T1)C Iycl£)C L/amprc^ (Petromyzon marinus unicolor Linnaeus). 



Life History. Let us begin the life history of the lamprey with the egg, as 

 nearly all animal life begins. Adult female Lake Lampreys lay between 25,000 and 

 30,000 eggs, according to size, the average being about 27,500. The eggs are laid in 

 " nests," to be described later, and hatch in from one to three weeks, according to 

 temperature. The warmer the water the sooner they hatch, the water at time of 

 hatching varying (for the two seasons observed) from sixty to sixty-two degrees 

 or more. 



When first laid the eggs are adhesive and stick to grains of sand and pebbles. Thus 

 they are held to the bottom and are covered with sand by the adults in the manner 

 described elsewhere. They are at first nearly white and translucent, but soon become 

 sulphur yellow and entirely opaque. When first hatched the young look like minute 

 light yellow worms, not over an eighth of an inch in length. They lie in the sand at 

 the bottom of the old spawning bed, and burrow still deeper, feeding on the micro- 

 organisms that are found there. Of course the quantity of their food is limited in 

 such a place, and their growth is very slow. They may not attain a greater length 

 than one and one half inches during the first year, as that is the smallest size we have 

 found in the sand in the spring time when eggs are again being deposited. Specimens 

 can be found ranging in length from this size to five or six inches, all taken from the 



* It is interesting to note that Dr. Dean and Mr. Sumner have found them spawning in numbers 

 in New York city as early as April 16. 



