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Karpovich S, Skinner JP, Miller CN, Polasek LK, Pendleton G. Growth and Shedding of Harbor Seal (Phoca vitulina) Whiskers. CAN J ZOOL 2022. [DOI: 10.1139/cjz-2021-0205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Accurate and precise estimates of the timing of whisker growth and shedding are necessary to interpret biochemical information stored in whiskers. This fine-scale examination of harbor seal (Phoca vitulina Linnaeus, 1758) whisker growth and shedding identified an asymptotic growth pattern with initial rapid growth that decays over time that can be defined with the von Bertalanffy curve. Initial growth rates were similar among whiskers, but estimated growth coefficients (K) and asymptotic lengths (L<sub>∞</sub> ) differed by follicle positions suggesting that differences in total whisker lengths result from dissimilarly shaped growth curves. In other words, longer whisker length is attained by delaying the growth rate decay. There was substantial intra- and inter-seal variation in shedding dates; whisker shedding began at the caudal margin of the whisker bed and progressed toward the nose. Shedding of marked whiskers from the three study seals took from 78 to 133 d, however, selecting whiskers only from the most caudal follicle of the bottom three rows constrained the period of whisker shedding to 7 to 43 d. These differences in growth and shedding of harbor seal whiskers emphasize the importance of considering follicle position to select whiskers that are the most similar for analyses of information stored in whiskers.
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Affiliation(s)
- Shawna Karpovich
- State of Alaska Department of Fish and Game, 10936, Marine Mammal Program, Fairbanks, Alaska, United States
| | - John P. Skinner
- State of Alaska Department of Fish and Game, 10936, Alaska Department of Fish and Game, Anchorage, Alaska, United States
| | - Carlene N. Miller
- State of Alaska Department of Fish and Game, 10936, Marine Mammal Program, Fairbanks, Alaska, United States
- Alaska SeaLife Center, Seward, Alaska, United States
| | - Lori K. Polasek
- Alaska SeaLife Center, Seward, Alaska, United States
- University of Alaska Fairbanks, 11414, College of Fisheries and Ocean Sciences, Fairbanks, Alaska, United States
- State of Alaska Department of Fish and Game, 10936, Marine Mammal Program, Juneau, Alaska, United States
| | - Grey Pendleton
- State of Alaska Department of Fish and Game, 10936, Wildlife Conservation, Juneau, Alaska, United States,
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Attard MRG, Lewis A, Wroe S, Hughes C, Rogers TL. Whisker growth in Tasmanian devils (
Sarcophilus harrisii
) and applications for stable isotope studies. Ecosphere 2021. [DOI: 10.1002/ecs2.3846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Marie R. G. Attard
- Department of Biological Sciences Royal Holloway University of London Egham TW20 0EX UK
- Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences University of New South Wales Sydney New South Wales Australia
| | - Anna Lewis
- Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences University of New South Wales Sydney New South Wales Australia
- The Carnivore Conservancy Ulverstone Tasmania Australia
| | - Stephen Wroe
- Function, Evolution and Anatomy Research Laboratory School of Environmental and Rural Science University of New England Armidale New South Wales Australia
| | - Channing Hughes
- The Carnivore Conservancy Ulverstone Tasmania Australia
- School of Life and Environmental Sciences The University of Sydney Sydney New South Wales Australia
| | - Tracey L. Rogers
- Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences University of New South Wales Sydney New South Wales Australia
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Smith J, Karpovich S, Horstmann L, McIntyre J, O’Brien DM. Seasonal differences in foraging and isotopic niche width related to body size in Gulf of Alaska harbor seals. CAN J ZOOL 2019. [DOI: 10.1139/cjz-2019-0108] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Harbor seals (Phoca vitulina Linnaeus, 1758) use different foraging strategies based on body size and sex, but this difference can be difficult to evaluate across seasons. We used stable isotope analysis of harbor seal whiskers from 32 individuals to assess seasonal foraging of seals inhabiting tidewater glacial habitat in Southeast Alaska. We analyzed stable isotope ratios from serial sections of whiskers, estimated deposition date for each section, and used mixed models to determine if sex and body size influence stable isotope ratios. Seals were grouped by size (>1.4 m or ≤1.4 m curvilinear length) as a proxy for sexual maturity to describe isotopic differences between groups using standard ellipse corrected area. Mean carbon and nitrogen isotope ratios differed significantly between size classes (p < 0.005), with no effect of sex. Larger seals exhibited a broader isotopic niche in the fall, winter, and spring relative to smaller seals, but not in the summer. Our results suggest that seals using tidewater glacial habitat share common foraging behavior in the summer, while larger seals exhibit more diverse foraging throughout the rest of the year. These results highlight the importance of tidewater glacial habitat for this population of harbor seals during the summer.
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Affiliation(s)
- Justin Smith
- Alaska Department of Fish and Game, 1300 College Road, Fairbanks, AK 99701, USA
| | - Shawna Karpovich
- Alaska Department of Fish and Game, 1300 College Road, Fairbanks, AK 99701, USA
| | - Lara Horstmann
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 232 Irving II, Fairbanks, AK 99775, USA
| | - Julie McIntyre
- Department of Mathematics and Statistics, University of Alaska Fairbanks, 513 Ambler Lane, Fairbanks, AK 99775, USA
| | - Diane M. O’Brien
- Institute of Arctic Biology, University of Alaska Fairbanks, P.O. Box 757000, Fairbanks, AK 99775-7000, USA
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