During the free floating stage, lasting up to six months, the postlarvae go 

 through a number of developmental stages, two of which are indicated in Figures 

 8 and 9. During this time they rise toward the surface and are carried into the 

 shallower section of the continental shelf by the prevailing wind-driven currents. 

 At this time, there is a change in form or metamorphosis, the left eye migrates over 

 the snout and the young fish are ready to commence their bottom existence as juvenile 

 halibut possessing the characteristic adult form (Figure 10). 



%i 



Figure 8. Halibut mid-postlarva. Size: 2.2 cm. (7/8 inch). 



Figure 9. Halibut late postlarva, showing beginning of eye migration. Size: 2.5 cm. (1 inch). 



■>*-*- = 



Figure 10. Young halibut, adapted to life on bottom. Size: 3.5 cm. (1 3/8 inch). 



The entire early life history of the halibut, from the time of spawning until they 

 reach the juvenile stage, is closely adapted to the general ecology and movements of 

 the water masses of the North Pacific Ocean and Bering Sea. 



The younger juveniles, from one to three years old tend to remain on the inshore 

 grounds before moving offshore where they first enter the commercial setline fishery 

 in significant numbers at about five to seven years of age. 



The survival of the young halibut can be affected by natural variations in the 

 environment, and, accordingly, some year classes will be more abundant than others. 

 A series of weak or strong year classes can affect the size or productivity of the 

 adult population upon which the fishery depends. 



