The incidence of twins in pinnipeds

1982 ◽  
Vol 60 (9) ◽  
pp. 2226-2233 ◽  
Author(s):  
Stephen Spotte
Keyword(s):  
Literature Search ◽  
Harbor Seals ◽  
Grey Seal ◽  
Northern Fur Seal ◽  
Sea Lion ◽  
California Sea Lion ◽  
Twin Birth ◽  
Fur Seal ◽  
In Captivity ◽  
In The Wild

The incidence of twins in pinnipeds is reviewed. Correspondence and a literature search revealed 42 documented cases involving 11 species (six phocids, five otariids). The greatest incidence was found in the grey seal and northern fur seal (7 and 11 cases, respectively). Two verified sets of triplets are known, both delivered by a single, captive grey seal. The odds of both pups of a viable twin birth surviving are slim. Both adoptive suckling and the suckling of two pups occur in some phocids, and the chances that twins will be reared are perhaps greater in these species. Neither behavior has been observed in otariids in the wild; however, a California sea lion that gave birth to twins in captivity suckled both pups until one was removed on day 15. Only two sets of twins (one set each of grey seals and harbor seals) are known to have survived to weaning, and both were captive born. The reproductive biology of pinnipeds does not favor twins, and their occurrence is rare, but probably not so rare as currently believed, because many observations are not published.

scholarly journals Studies on the Hemoglobins of Pinnipeds

Blood ◽  
1973 ◽  
Vol 41 (1) ◽  
pp. 163-170 ◽  
Author(s):  
David R. Lincoln ◽  
Diana T. Edmunds ◽  
T. John Gribble ◽  
Herbert C. Schwartz
Keyword(s):  
Gel Filtration ◽  
Elephant Seal ◽  
Harbor Seals ◽  
Major Fraction ◽  
Sea Lion ◽  
California Sea Lion ◽  
Deep Diving ◽  
Heat Stable ◽  
Gray Harbor ◽  
Fur Seal

Abstract The hemoglobins of seven species of pinnipeds-elephant, ribbon, fur, harbor, and grey seals, walrus, and California sea lion-had two major and one minor hemoglobin fractions on electrophoresis at pH 8.6. One of the major fractions in all seven species had the same electrophoretic mobility. The second fractions of the gray, harbor, and ribbon seals were similar, but different from the second fractions of the walrus, fur seal, and sea lion. The second fraction of the elephant seal was different from all the others. The proportion of the two major fractions was about 3:1 in the elephant, grey, ribbon, and harbor seals, and about 1:1 in the fur seal, walrus, and sea lion. These results correlated well with the pinniped phylogenetic chart derived by classical morphology. All hemoglobin fractions were found to be alkali sensitive and heat stable. Gel filtration studies with Sephadex G-75 and G-100 indicated that the elephant seal hemoglobins had a mol wt of about 65,000. The amino acid compositions of the chains isolated from the hemoglobin fractions suggested that in the elephant seal one major fraction had two alpha and two beta chains, and the other major fraction had four like chains. The presence of a hemoglobin which is composed of a tetramer of like chains could be functionally advantageous to deep diving mammals.

UNCINARIASIS IN NORTHERN FUR SEAL AND CALIFORNIA SEA LION PUPS FROM CALIFORNIA

1997 ◽  
Vol 33 (4) ◽  
pp. 848-852 ◽  
Author(s):  
Eugene T. Lyons ◽  
Robert L. DeLong ◽  
Sharon R. Melin ◽  
Sharon C. Tolliver
Keyword(s):  
Northern Fur Seal ◽  
Sea Lion ◽  
California Sea Lion ◽  
Fur Seal

New data on the number of northern fur seal ( Callorhinus ursinus), Steller sea lion ( Eumetopias jubatus), and spotted seal ( Phoca largha) at Tyuleny Island (Okhotsk Sea)

2014 ◽  
Vol 178 (3) ◽  
pp. 87-94
Author(s):  
Alexey E. Kuzin
Keyword(s):  
Steller Sea Lion ◽  
Callorhinus Ursinus ◽  
Okhotsk Sea ◽  
Eumetopias Jubatus ◽  
Northern Fur Seal ◽  
Sea Lion ◽  
Spotted Seal ◽  
Phoca Largha ◽  
Fur Seal ◽  
June July

The latest data on abundance and distribution of northern fur seal ( Callorhinus ursinus ), Steller sea lion ( Eumetopias jubatus ), and spotted seal ( Phoca largha ) at Tyuleny Island (Okhotsk Sea) are presented. The total counted number of fur seals was 115 thousand in June-July of 2013, including 5.0 thousand of bulls, 30.3 thousand of females, and 34.7 thousand of pups (31.5 thousand alive and 3.2 thousand dead). Decreasing of the females and pups number is observed during the last 4 years - they became lesser in 18.0 % or 4.5 % per year. The counted number of Steller sea lions was 1879 adults (including 119 bulls, and 1390 females, 68.5 % of them gave birth) and 890 pups. The reproductive group of Steller sea lion increases its abundance on the island due to numerous immigrants. Abundance of spotted seal was very various seasonally and even daily, its highest counted number was 162 individuals.

Use of satellite-linked telemetry to study Steller sea lion and northern fur seal foraging

1994 ◽  
Vol 13 (1) ◽  
pp. 105-114 ◽  
Author(s):  
R. L. MERRICK ◽  
T. R. LOUGHLIN ◽  
G. A. ANTONELIS ◽  
R. HILL
Keyword(s):  
Steller Sea Lion ◽  
Northern Fur Seal ◽  
Sea Lion ◽  
Fur Seal

Use of satellite-linked telemetry to study Steller sea lion and northern fur seal foraging

1994 ◽  
Vol 13 (1) ◽  
pp. 105-114 ◽  
Author(s):  
R. L. Merrick ◽  
T. R. Loughlin ◽  
G. A. Antonelis ◽  
R. Hill
Keyword(s):  
Steller Sea Lion ◽  
Northern Fur Seal ◽  
Sea Lion ◽  
Fur Seal
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