146 



U. S. BUREAU OF FISHEEIES 



AVERAGE HAREM 



The average harem is determined on the basis of an increase of 8 

 percent for the cows. The estimated average harem for the two 

 islands this season was 43.43. This may be considered as quite 

 satisfactory. 



Aside from actual counts or estimates of males and females, observ- 

 ations indicated that there were sufficient breeding males on the 

 rookeries this season. Even during the last week of July there were 

 idle bulls in the rear of the rookeries, and a fair number of large males 

 or surplus bulls in good condition were in the drives at the end of the 

 season. 



It is very important that a proper or sufficiently low average harem 

 be maintained. If the average harem is too large it is clearly indicative 

 that too many males have been Idlled. It does not hurt the herd to 

 have a low average harem; but a high average harem, or, in other 

 words, a shortage of breeding males, is a sure indication that all cows 

 are not being bred. 



Estimated number of harem and idle bulls, approximate ratio of idle bulls to harem 

 bulls, and average harem, 1937 



PUPS AND COWS 



No pup count having been made since 1922, an average rate of 

 increase of 8 percent has been used each year since that date to 

 determine the number of cows and pups in the herd. 



The percentage of dead pups determined by actual count in 1922 

 was again applied to show the number dead on each rookery. For 

 comparative purposes the dead pups are included in the total number 

 of pups. The figures given are probably considerably under the actual 



