234 THE PUR SEALS OP THE PRIBILOP ISLANDS. 



sealing in this 'section of the Northwest sealing belt, the season closing April 30, 

 before sealing operations have extended to the westward of the Eairweather ground. 



While the restrictions placed on pelagic sealing at various times during the last 

 half dozen years have scattered the fleet over all parts of the Pacific Ocean north of 

 latitude 35°, it does not appear from the abundant sealing records at hand that seals 

 occur in important numbers anywhere outside of the coastwise hunting grounds 

 already outlined. 



In June and July sealers passing from the Japan coast to Bering Sea or to North 

 American ports pick up stragglers, consisting chiefly of young seals, at many points 

 in mid-ocean, but the entire number of seals taken in this way would probably not 

 exceed a thousand. 



COMPARISON OF MIGRATION ROUTES. 



Although the American and Asiatic seal herds migrate between the same degrees 

 of latitude — 34° and 00° north — the length of the route followed by the former is 

 nearly twice that of the latter. It extends not merely through 26 degrees of latitude, 

 but through 56 degrees of longitude, or from longitude 119° to 175° west, while the 

 Asiatic herd has but 30 degrees to traverse, or from longitude 141° to 171° east. The 

 extreme range of the American herd is but little short of 3,500 miles. Both herds 

 arrive at and depart from the summer habitat in Bering Sea simultaneously, but 

 there the resemblance iu their respective migratory movements begins to diminish. 

 What the ocean temperatures, currents, and prevailing winds they encounter along 

 their respective migration routes may have to do with their progress we do not know, 

 but it appears that the American herd, traversing a vastly longer route, reaches the 

 common southern limit of 34° first. Its movement for the next six months is slowly 

 and steadily northward toward the summer habitat, which is reached by the adult 

 portion of the herd but little earlier than the actual commencement of the breeding 

 season. The younger classes of seals arrive somewhat later. 



The Asiatic herd, on the contrary, lingers in the winter habitat until the breeding 

 season is near, when its northward movement is sudden and rapid. The two herds 

 thus differ much in the course and extent of their migration routes and the progress 

 they make in following them. 



SEALING GROUNDS IN RELATION TO PISHING BANKS. 



I 



It does not appear that the various tracts of ocean frequented by the seals during 

 their seasonal movements have any very direct relation to the coast fishing banks, as 

 the greater part of any sealing ground is off soundings. On the Japan sealing ground 

 the hundred-fathom line is reached at a distance averaging less than 10 miles from the 

 shore, while a few miles beyond it exist some of the most profound depths that have 

 yet been sounded. Ev§n in the great gulf opposite the Straits of Tsugar, where an 

 important part of the Japan seal catch is made, the hundred-fathom curve follows the 

 shores, an arm of the deep sea penetrating far in between the islands. The same is 

 true of the Commander sealing ground, the hundred fathom line being everywhere 

 close along shore, while at the southern border of this sealing ground there exists a 

 depth of 2 miles. 



Fully three-fourths of the Pribilof sealing ground lies off the western border of 

 the great plateau from which the Pribilof Islands rise. Perhaps the seals would not 

 be found on soundings there were it not that their breeding grounds are located far 

 back on the plateau. 



