Estimation of Sexual Maturity Based on Morphometrics of Genital Organs in Male Northern Fur Seals, Callorhinus ursinus

Mammal Study ◽  
2020 ◽  
Vol 46 (1) ◽  
Author(s):  
Yukino Hirakawa ◽  
Takanori Horimoto ◽  
Ippei Suzuki ◽  
Yoko Mitani
Keyword(s):  
Sexual Maturity ◽  
Callorhinus Ursinus ◽  
Fur Seals ◽  
Northern Fur Seals

NATURALLY-OCCURRING LEPTOSPIROSIS IN NORTHERN FUR SEALS (Callorhinus ursinus)

1977 ◽  
Vol 13 (2) ◽  
pp. 144-148 ◽  
Author(s):  
ALVIN W. SMITH ◽  
RICHARD J. BROWN ◽  
DOUGLAS E. SKILLING ◽  
H. L. BRAY ◽  
MARK C. KEYES
Keyword(s):  
Callorhinus Ursinus ◽  
Naturally Occurring ◽  
Fur Seals ◽  
Northern Fur Seals

scholarly journals Fortuitous Encounters between Seagliders and Adult Female Northern Fur Seals (Callorhinus ursinus) off the Washington (USA) Coast: Upper Ocean Variability and Links to Top Predator Behavior

PLoS ONE ◽  
2014 ◽  
Vol 9 (8) ◽  
pp. e101268 ◽  
Author(s):  
Noel A. Pelland ◽  
Jeremy T. Sterling ◽  
Mary-Anne Lea ◽  
Nicholas A. Bond ◽  
Rolf R. Ream ◽  
...  
Keyword(s):  
Adult Female ◽  
Upper Ocean ◽  
Callorhinus Ursinus ◽  
Top Predator ◽  
Ocean Variability ◽  
Fur Seals ◽  
Northern Fur Seals ◽  
Predator Behavior

Estimating the Juvenile Survival Rate of Male Northern Fur Seals (Callorhinus ursinus)

1989 ◽  
Vol 46 (8) ◽  
pp. 1428-1436 ◽  
Author(s):  
Andrew W. Trites
Keyword(s):  
Survival Rate ◽  
Juvenile Survival ◽  
Callorhinus Ursinus ◽  
Strongly Correlated ◽  
Fur Seals ◽  
Commercial Harvest ◽  
Northern Fur Seals ◽  
Back Calculation ◽  
Number Of Males ◽  
Insight Into

Three methods for estimating the survival rate of juvenile northern fur seals (Callorhinus ursinus) are developed from the earlier works of Chapman, Smith and Polacheck and Lander. Each of the methods I propose divides the estimated number of males alive at 2 yr of age by the estimated number of pups born in their year class. The number of surviving juveniles are reconstructed by back calculation using the number of males killed during the commercial harvest and the subsequent counts of bulls. The three methods differ in their assumptions concerning subadult survival and escapement from the harvest, although all produce similar estimates when applied to the St. Paul Island fur seals. These new estimates of juvenile survival (1950–80) are strongly correlated with the ratio of cohort kill to pup production and with estimates from the currently-used Lander procedure. This is because the harvest morality of males is large compared with natural morality. The new methods perform acceptably over a wider class of data than Lander's. Their greatest advantage over current procedures is that they provide a better insight into the reliability of the survival estimates they produce.

Digeneans of northern fur seals Callorhinus ursinus (Pinnipedia: Otariidae) from five subpopulations on St. Paul Island, Alaska

2018 ◽  
Vol 117 (4) ◽  
pp. 1079-1086 ◽  
Author(s):  
T. A. Kuzmina ◽  
V. V. Tkach ◽  
T. R. Spraker ◽  
E. T. Lyons ◽  
O. Kudlai
Keyword(s):  
Callorhinus Ursinus ◽  
Fur Seals ◽  
Northern Fur Seals

Stimuli for Parturition in Northern Fur Seals (Callorhinus ursinus)

1984 ◽  
Vol 65 (2) ◽  
pp. 333-336 ◽  
Author(s):  
M. A. Bigg
Keyword(s):  
Callorhinus Ursinus ◽  
Fur Seals ◽  
Northern Fur Seals

At-sea behavior of juvenile male northern fur seals (Callorhinus ursinus)

2004 ◽  
Vol 82 (10) ◽  
pp. 1621-1637 ◽  
Author(s):  
J T Sterling ◽  
R R Ream
Keyword(s):  
Body Mass ◽  
Mass Gain ◽  
Callorhinus Ursinus ◽  
Juvenile Male ◽  
Deep Waters ◽  
Fur Seals ◽  
Straight Line ◽  
Northern Fur Seals ◽  
Straight Line Distance ◽  
Pribilof Islands

The at-sea behavior of juvenile male northern fur seals, Callorhinus ursinus (L., 1758), captured at two haul-out sites on St. Paul Island, Alaska, during the 1999 and 2000 breeding seasons (July–September) was studied. To compare at-sea locations, dive behavior, and changes in body mass, 31 juveniles between the estimated ages of 3–6 years were captured, instrumented, and released. Individuals behaved like central-place foragers by making trips to sea and returning to the Pribilof Islands. Trip durations ranged between 8.74 and 29.81 d, whereas distances from departure site ranged between 171.27 and 680.68 km (maximum straight-line distance). Differences in maximum straight-line distance traveled and trip duration were not observed when comparing years or departure site. Diving tended to reflect patterns associated with different bathymetric domains; shallow nighttime diving was common in ~3000 m deep waters, whereas deeper diving was generally observed in <200 m deep waters. Proportion of body mass gained over a single trip to sea averaged 27.8% (range 3%–65%, n = 19). Mass gain was similar between individuals that dove in shallow waters (over the continental shelf; 10.9 ± 1.8 kg (mean ± 1 SE), n = 11) versus individuals that dove in pelagic waters (8.5 ± 1.0 kg, n = 8). These results demonstrate that the at-sea behavior of juvenile males can extend farther from the Pribilof Islands when compared with previous reports of parturient female at-sea behavior, thus revealing important variation within this species.

Measurement of Diet Preference and its Variability in Captive Northern Fur Seals (Callorhinus ursinus)

Mammal Study ◽  
2013 ◽  
Vol 38 (3) ◽  
pp. 199-210 ◽  
Author(s):  
Masashi Kiyota ◽  
Hiroshi Okamura ◽  
Hiroya Itou ◽  
Noriyasu Suzuki ◽  
Kaoru Kohyama
Keyword(s):  
Callorhinus Ursinus ◽  
Fur Seals ◽  
Diet Preference ◽  
Northern Fur Seals
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