Details:

Journal Title:
Ecosphere
Personal Author:
Warlick, Amanda J. ; Johnson, Devin S. ; Gelatt, Tom S. ; Converse, Sarah J.
Warlick, Amanda J. ; Johnson, Devin S. ; Gelatt, Tom S. ; Converse, Sarah J. Less -
NOAA Program & Office:
NMFS (National Marine Fisheries Service) ; AFSC (Alaska Fisheries Science Center) ; PIFSC (Pacific Islands Fisheries Science Center)
NMFS (National Marine Fisheries Service) ; AFSC (Alaska Fisheries Science Center) ; PIFSC (Pacific Islands Fisheries Science Center) Less -
Description:
Understanding what drives changes in wildlife demography is fundamental to the conservation and management of depleted or declining populations, though making inference about the intrinsic and extrinsic factors that influence survival and reproduction remains challenging. Here we use mark–resight data from 2000 to 2018 to examine the effects of environmental variability on age-specific survival and natality for the endangered western distinct population segment (wDPS) of Steller sea lions (Eumetopias jubatus) in Alaska, USA. Though this population has been studied extensively over the last four decades, the causes of divergent abundance trends that have been observed across the wDPS range remain unknown. We developed a Bayesian multievent mark–resight model that accounts for female reproductive state uncertainty. Annual survival probabilities for male pups (0.44; 0.36–0.53), female yearlings (0.63; 0.49–0.73), and male yearlings (0.62; 0.51–0.71) born in the western portion of the wDPS range, estimated here for the first time, were lower than those in the eastern portion of the wDPS range, estimated as: male pups (0.69; 0.65–0.74), female yearlings (0.76; 0.71–0.81), and male yearlings (0.71; 0.65–0.78). There was a higher proportion of young female breeders in the western portion of the range, but overall natality was lower (0.69; 0.47–0.96) than in the eastern portion of the range (0.80; 0.74–0.84). Additionally, pup mass had a positive effect on pup survival in the eastern portion of the range and a negative effect in the western portion of the range, potentially due to earlier weaning of heavier pups. Local- and basin-scale oceanographic features such as the Aleutian Low, the Arctic Oscillation Index, the North Pacific Gyre Oscillation, chlorophyll concentration, upwelling, and wind in certain seasons were correlated with vital rates. However, drawing strong inferences from these correlations is challenging given that relationships between ocean conditions and an adaptive top predator in a dynamic ecosystem are exceedingly complex. This study provides the first demographic rate estimates for the western portion of the range where abundance estimates continue to decline. These results will advance efforts to identify factors driving regionally divergent abundance trends, with implications for population-level responses to future climate variability.
Keywords:
[+]
Ecology Ecology, Evolution, Behavior And Systematics
Source:
Ecosphere, 13(12)
DOI:
https://doi.org/10.1002/ecs2.4325
ISSN:
2150-8925;2150-8925;
Format:
PDF
Publisher:
Wiley
Document Type:
Journal Article
License:
https://creativecommons.org/licenses/by/4.0/
Rights Information:
CC BY
Compliance:
Submitted
Main Document Checksum:
[+]
urn:sha256:4a14fcc6dcfdd884f01a9963074c40fa086940d89c8475541e9115b0a77bc074
Download URL:
https://repository.library.noaa.gov/view/noaa/50993/noaa_50993_DS1.pdf
File Type:

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