SURVEY DATA 



Data collected in 1967 to follow the response 

 of the population to changes in its size in- 

 cluded: (1) Counts of dead pups and adults; 

 (2) counts of living adult males; (3) major 

 causes of mortality of pups; (4) reproductive 

 condition of females; and (5) weights of live 

 pups. 



MORTALITY 



This section includes data on pups that died 

 on the Pribilof Islands during most years since 

 1941, and adults that died on St. Paul Island in 

 1965-67 and on St. George Island in 1966-67. 



Pups 



Biologists have counted dead pups on the 

 Pribilof Islands about mid- August nearly every 

 year since 1948 (table A-9). In 1966 and 1967 

 we also recorded the number of pups that died 

 within sections established on each of the St. 

 Paul Island rookeries. Table A- 10 shows the 

 counts obtained by section in 1967. 



In 1967 we recorded the causes of death 

 among pups on three rookery areas selected 

 for sampling. 



Counts of dead pups . - - The count of dead pups 

 on the Pribilof Islands in 1967 was 17,426; 

 14,780 were on St. Paul Island and 2,646 were 

 on St. George Island (table A-9). 



Causes of pup mortality. - -From 29 June to 

 15 August, 232 dead pups were necropsied. The 

 pups were gaffed from catwalks in two areas on 

 Reef Rookery and one on Northeast Point 



Rookery (figs. 5 and 6). Collections from the 

 two rookeries were alternated daily. Table 4 

 gives the distribution of the five primary causes 

 of death, of the miscellaneous causes, and of 

 the undetermined causes. 



1. Malnutrition. Mortality from malnutri- 

 tion on area 1, though of about the same 

 magnitude as in 1966 (table 5), was about 15 

 percent higher than the average loss from this 

 cause on areas 2 and 3 (table 4). 



2. Liver damage-multiple hemorrhage- 

 perinatal complex. This condition is charac- 

 terized by one or all of the following lesions: 

 interruption of the liver capsule and cor- 

 responding separation of the liver parenchyma; 

 subcapsular hemorrhage of the liver causing 

 separation of capsule and parenchyma to form 

 blood blisters 3 to 50 mm. in diameter; foci 

 of hepatic necrosis which form stellate areas of 

 increasing size as the post mortem period 

 lengthens; subpleural hemorrhage of other 

 organs such as the lung and kidney; free blood 

 in the anterior chamber of both eyes; and free 

 blood in the peritoneal cavity. The condition 

 is perinatal; it is usually found in pups with 

 attached placentas or fresh umbilical cords, 

 and frequently in stillborn pups. Thirty-eight 

 percent of pups with rupture of the liver showed 

 no evidence of bite wounds or contusions. 



We believed that the total of 11 dead (4 per- 

 cent) among 273 pups in 1964 and 1966 was 

 caused by simple trauma (physical injuries). 

 The 40 cases from 232 dead pups in 1967 is a 

 fourfold increase. The multiple necrotic foci 

 and subcapsular hemorrhages observed on 12.5 

 and 22.5 percent, respectively, of the livers of 

 these 40 pups, are lesions we have never seen 

 in fur seals before. One of the most striking 

 features revealed by post mortem examinations 



Figure 5. — Pup mortality, study areas 1 and 2, Reef Rookery, St. Paul Island, mid-July 1967. 



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