1897-8- TRANSACTIONS. d"] 



While speaking of the young seals reference may be 

 made to the known causes of their destruction and the sup- 

 posed effects of pelagic sealing. Dead pups were never noted 

 in large numbers on the Pribylov Islands until 1891 when sev- 

 eral thousand were found on one rookery by the British Com- 

 missioners. Dr. Geo. M. Dawson "lartd Sir George Baden- 

 Powellj^lhe U. S. Treasury Agents on the islands, could not 

 at first account for this great mortality, but finally attributed 

 it to pelagic sealing. The mothers of these pups had 

 been killed at sea they said, and the young had died, 

 of starvation. This hypothesis was made the basis of one 

 sectioij of the United States case and although shown 

 to be untenable is still maintained. It was shown by the 

 British Commissioners that in 1891 pelagic sealing had under 

 the modus vive7idi of that year ceased long before the 

 date at which the pups seen by them died, but it was still 

 maintained by the United States that pelagic sealing was 

 the cause of the mortality. In 1892 no seals were killed by 

 pelagic sealers in Behring Sea, but in that year I found an 

 even greater number of dead pups on the rookeries. Sealing at 

 sea had evidently not caused the death of these pups, and this 

 was the view taken by the arbitrators at Paris in 1892, None 

 of the natural causes of destruction known to us seemed adequate 

 to explain this great mortality. Those that came under our 

 observation were trampling or crushing by older seals, drown- 

 ing, straying away from their home rookeries, and a few minor 

 causes. None of these explained the deaths of large numbers 

 of young seals on restricted areas and though no trace of an epi- 

 demic could be found this explanation first advanced by the 

 British Commissioners seemed the only reasonable one. In 

 1896, in company with Dr. Jordan, the U. S. Commissioner, I 

 counted over 11,000 dead pups on the rookeries before pelagic 

 sealing began. Later in the season — in October — we again 

 counted the dead pups and found that about the same number 

 had died since the date of our first count early in August. 

 Ignoring the fact that whatever the causes of death might 

 have been early in the season they were probably in operation 

 throughout the season, it was assumed by the agents of the 

 United States that these later deaths were all due to starvation. 

 No new cause of destruction was found in 1896, Dr. Jordan being 

 of the opinion that the principal cause of death was trampling 

 by older seals. In 1897, however, acting upon the suggestion 

 of Dr. Styles, of Washington, we discovered that the chief 

 cause of death was a small parasitic worm, a species of Uucin- 



