Vl.-THE CAUSES OF MORTALITY AMONG SEALS. 



By Fkedeuic A. Lucas. 



Those who have read the testimony sixbinitted to the Paris tribunal must have 

 been struck with the great diversity of statements regarding the death rate among 

 seals, and particularly among young seals, for it was positively asserted and quite as 

 positively denied that numbers of seal, pups died annually prior to the 1st of August. 

 In view of these contiictiiig statements it was obviously of great importance to ascer- 

 tain not only the number of pups which died before the commencement of pelagic 

 sealing, but the causes which led to their death. Every effort was therefore made 

 to obtain information on these points, and this jwrtion of the report may be said to 

 represent the results of the observations of all members of the various commissions. 

 A count was made of the dead pups as early in August as circumstances would admit, 

 while autopsies, recorded further on, were performed on as many bodies as were 

 sufficiently well preserved to allow of its being done. 



It is not pretended that there may not be many more diseases among seals and 

 many more causes for their death than are herein set forth, but the intent of this 

 chapter is to show what we actually know about these matters. There has been 

 entirely too much theory and entirely too little observation and record of facts in 

 treating of the fur seal, and it is mere idle speculation to say from what diseases they 

 might or might not die. It seems to have been generally considered that the death 

 rate among pup seals was low, the chief destruction being caused by surf and killer 

 whales. Photographs taken by Mr. Macoun in 1891 and 1892 (see PI. XVI), however, 

 showed that on some i)ortions of Tolstoi and Polovina there were certainly large 

 numbers of dead pups far above the surf mark which had perished long before the 

 middle of August and before the effects of pelagic sealing could be felt. It therefore 

 became an interesting question whether or not there was any reason why the deaths 

 on these rookeries should be more numerous than elsewhere. 



Up to the 1st of August it was not only impossible to enter the breeding grounds, 

 but impossible to approach them very closely, not so much from the danger of 

 stampeding the rookeries as from the danger of being stampeded by angry bulls. By 

 August 8 the rookeries had opened out somewhat, the seals having largely drawn 

 back from the water, and on that date the dead pups on Kitovi, Lukanin, and the 

 Eeef were counted. It was no easy matter to enter a rookery even on that date, and 

 it required much skill in dodging active and angry bulls and a cautious collecting of 

 bodies with long gaffs to make the count complete and to gather any subjects fit for 

 dissection. While the result of this count was surprising, 1,264 dead pups being 

 found m 1896 on the three rookeries named, the counts of Polovina, made on August 

 10, and of Tolstoi, made on August 12, were still more startling, revealing as they did 



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