376 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 5 



mortality, or any increase in young due to previously increased 

 spawning. The most that can at present be said is that the changes 

 seem to be those expected. 



These considerations also have led to the study of eggs and larvae. 

 This study is significant for two reasons: (1) Because these drift 

 with the currents and may be carried from bank to bank (the exist- 

 ence and extent of this drift would greatly modify any regulations 

 designed to increase the spawn if this came from areas other than 

 those affected) and (2) because their abundance, as measured by the 

 catch per net haul, should reflect the increase in numbers of adults. 

 It is a more direct way of measuring this increase than the market 

 measurements discussed above, because the commercial fishery may 

 take varying percentages of the adults on the banks and is really what 

 is taken rather than what is left. 



The eggs and youngest stages of the halibut had never been de- 

 scribed in the Atlantic despite the extensive work that had been car- 

 ried on there upon the eggs and young of other forms. It is true 

 that some of the older stages had been found, but in very small num- 

 bers. It was therefore with much satisfaction that the Commission 

 was able to find an abundance on the western banks where depletion 

 had not been as extensive (pi. 2). 



By examining the catch of adults it was found that the spawning 

 season is from the middle of December to near the last of March. 

 The adult fish collect in schools at the edge of the continental shelf. 

 These schools begin to collect in November, and at that time the 

 fishermen find schools of males and of females migrating actively. 

 Although these mature fish had become i-elatively scarce in southern 

 waters at the time the treaty of 1924 became effective, because of the 

 intense fishery there, they still existed in considerable numbers along 

 the banks from the Gulf of Alaska west. There the egg of the 

 halibut was found and described. It was one of the largest of the 

 fish eggs found, being some 3^ to 3l^ millimeters in diameter. The 

 eggs were laid at the edge of the continental shelf in depths of about 

 150 fathoms. They were then drifting freely with the currents, and 

 by means of large, fine-meshed silk nets great numbers of them were 

 caught. To work out their distribution and rate of development, 

 hauls with these silk nets were made over a large part of the north 

 Pacific between the entrance of Bering Sea and the coasts of Alaska 

 and British Columbia. During one winter the vessel used logged 

 over 10,000 miles. It was found that the young drifted with the 

 ocean waters, developing slowly in much the same way that had often 

 been described for flounders or soles. After hatching, the young 

 transparent larvae swam upright, an eye on each side, as any normal 

 fish should do. It grew steadily in depth of body until, in its fourth 



