Fishes of the Western North Atlantic 



465 



almost simultaneously. The complete operation, observed in the case of a nine-pound 

 female and a five-pound male, consisted of eight emissions in different beds prepared by 

 the female. After each spawning act, the female moved upstream of the bed and cut 

 vigorously with her tail, thus covering the eggs with gravel. Each spawning act took 

 place in 10-15 seconds, and the eggs were completely covered about 30 seconds later. 



I 



o 



z 



z 



I 

 1- 



z 



10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 



WEIGHT IN POUNDS 



Figure 122. Length-weight relationship for Atlantic Salmon. 



In the experimental tank, spawning took place at temperatures varying between 

 36— 42°F. Of the eggs collected from 12 nests, 97.6 "/o had been fertilized. 



An interesting feature of the spawning of the Atlantic Salmon is the participation 

 in it of male parr. That some parr become sexually mature before they leave the river 

 has long been known. As early as 1686, Willughby wrote that while female parr (salm- 

 olus) never have ripe eggs, male salmolus fertilize the eggs of the adults (146). These 

 early observations have been amply confirmed in recent careful studies by Aim (j) and 

 others (8o\ 81 \ 82 \ III). According to Jones, 75 "/g of the male parr become sexually 

 mature during river life (j8'. 128). Their sperm is as effective in artificial fertilization 

 of the eggs as is the sperm stripped from adults. Eggs fertilized by parr sperm 

 produce normal progeny, and male parr under natural conditions may be responsible 

 for fertilizing a considerable fraction of the total number of eggs that develop. It has 



30 



