225 



an estimated pregnancy rate of 0.6, the number of pups born equals 60 percent 

 of the females of breeding age (4 and older) ; (2) that the estimated annual 

 death rate among breeding females is 0.11, which means that 11 percent of these 

 animals must be replaced each year to maintain the breeding stock, and (3) that 

 with an approximately equal survival rate of the sexes to age 4, the number of 

 females available from each year class as potential breeders can be estimated 

 from the survival (harvest) of males. The take of females is thus adjusted 

 to fit the program objective and needs of the herd in terms of breeding stock. 



Question No. 16. What do you believe to be the maximum sustainable yield of 

 this herd? What is the optimum sustainable yield? 



Answer. See information provided in number 4 above. 



Question No. 17. What figures do you have to indicate any attrition to the herd 

 by reason of starvation or maltiutrition? 



Answer. The death rate among fur seals is high early in life, then tapers to a 

 low level before rising among older animals. The main cause of death among a 

 few hundred pups examined on St. Paul Island since 1962 has been malnu- 

 trition (range 21-48 percent). Hookworm disease, bacterial infections, and 

 injuries follow in order of importance. Compared to the total number of dead 

 pups (about 281,000) counted on the Pribilof Islands since 1962, it is difficult to 

 say whether or not the relatively small sample of pups examined is representative 

 of reality. Further, by far the greatest proportion of mortality occurs at sea after 

 the pups leave the Pribilof Islands in November. Good information is lacking on 

 the relative causes of death among fur .seals at sea, and on what role malnutrition 

 and other factors play in the magnitude of mortality. 



U.S. Department of Commebce, 

 National Marine Fisheries Service, 



August, 1971. 



Investigations and Experiments Pertaining to Fur Seal 

 Slaughtering Methods 



SUMMARY 



1. Criticism of the method used to harvest fur seals on the Pribilof Islands 

 has been inreasing in recent years. The criticism has been directed primarily 

 against use of a club to stun fur seals. The Marine Mammal Resources Program 

 has resiDonded to the compliants by seeking expert advice on how to improve 

 procedures of harvesting fur seals. 



2. In 19 >7 Dr. Elizabeth Simpson, a veterinarian from the University of Cam- 

 bridge in England, repre senting the World Federation for the Protection of 

 Animab-, and Mr. Brian E. Davies, representing the Humane Society of the 

 United States, observed the harvest on the Pribilof Islands. Dr. Simpson con- 

 cluded "that the Pribilof fur seal harvest is at present being carried out in a 

 reasonably humane fashion, which could, however, be improved by attention to a 

 few details." Mr. Davies recommended several changes to make the harvesting 

 procedures more humane and suggested that research be started on mechanical 

 methods of slaughter. 



3. In 1!>68 the Department of Interior appointed a task force consisting of 

 representatives from the National Academy of Sciences, The Humane Society 

 of the United States, The Livestock Slaughter Division of the Department of 

 Agriculture, Bureau of Sports Fisheries and Wildlife and, Bureau of Commer- 

 cial Fitiheries. Alternative methods of killing were investigated, including carbon 

 dioxide induced hyix)xia, electrocution, shooting, and stunning with clubs and 

 concussion bolts. The task force decided not to test drugs because of the residue 

 remaining in the meat and the fact that extensive work had already been done 

 on drugs. The results of the tests indicated that none of the alternative methods 

 was as rapid and effective as the traditional method, nor were they adaptable 

 to the harvest situation. 



4. However, the 1968 Task Force Report included recommendations for 

 changes in operational procedures that would cause stress to the animals, most of 

 which have been put into effect. 



5. In 1969 a contract w^as awarded the Virginia Mason Research Center in 

 Seattle to conduct a series of experiments using carbon dioxide and nitrogen 

 gasses to dispatch fur seals. These preliminary tests were followed by more 

 refined experunents during the 1970 season testing carbon dioxide, nitrogen, the 

 drug succinylcholine and conventional stunning and bleeding methods. Stunning 



