TY - JOUR
T1 - Population-level impacts of natural and anthropogenic causes-of-death for Hawaiian monk seals in the main Hawaiian Islands
AU - Harting, Albert L.
AU - Barbieri, Michelle M.
AU - Baker, Jason D.
AU - Mercer, Tracy A.
AU - Johanos, Thea C.
AU - Robinson, Stacie J.
AU - Littnan, Charles L.
AU - Colegrove, Katie M.
AU - Rotstein, Dave S.
N1 - Funding Information:
Observational data for seals in the main Hawaiian Islands were collected by a large contingent of dedicated and skilled observers, including both agency and citizen collaborators. While far too numerous to list, their efforts are greatly appreciated by researchers such as ourselves who are able to harvest the fruit of their work to undertake analyses like the one described herein. Multiple institutions and agencies assisted with the retrieval and transport of seal carcasses reviewed for this project, including The Marine Mammal Center, Ke Kai Ola, the U.S. Coast Guard, the U.S. Navy, and the Hawaii Department of Land and Natural Resources. We also thank the additional biologists and veterinarians who conducted or provided essential assistance in seal necropsies: Dr. Alonso Aguirre, Dr. Robert Braun, Dr. Frances Gulland, Angie Kaufman, Dr. Gregg Levine, and Dr. Mimi Olry. All work undertaken for this project was completed pursuant to permits #16632 and #18786.
Publisher Copyright:
© 2020 Society for Marine Mammalogy.
PY - 2021/1
Y1 - 2021/1
N2 - Identifying, assessing, and ranking the impact of individual threats is fundamental to the conservation and recovery of rare and endangered species. In this analysis, we quantify not only the frequency of specific causes-of-death (CODs) among Main Hawaiian Island (MHI) monk seals, but also assess the impact of individual CODs on the intrinsic growth rate, λ, of the MHI population. We used gross necropsy results, histopathology, and other evidence to assign probabilities of 11 COD types to each mortality and then used Monte Carlo sampling to evaluate the influence of each COD on λ. By right censoring realizations involving specific CODs, we were able to estimate λ (and its associated uncertainty) when CODs were selectively removed from influencing survival. Applying the analysis to all known and inferred deaths believed to have occurred 2004–2019, the CODs with the largest influence on λ were anthropogenic trauma, anthropogenic drowning, and protozoal disease. In aggregate, anthropogenic CODs had a larger effect on the growth rate than either natural or disease CODs. Possible bias associated with differential carcass detection, recovery, and COD classification are discussed.
AB - Identifying, assessing, and ranking the impact of individual threats is fundamental to the conservation and recovery of rare and endangered species. In this analysis, we quantify not only the frequency of specific causes-of-death (CODs) among Main Hawaiian Island (MHI) monk seals, but also assess the impact of individual CODs on the intrinsic growth rate, λ, of the MHI population. We used gross necropsy results, histopathology, and other evidence to assign probabilities of 11 COD types to each mortality and then used Monte Carlo sampling to evaluate the influence of each COD on λ. By right censoring realizations involving specific CODs, we were able to estimate λ (and its associated uncertainty) when CODs were selectively removed from influencing survival. Applying the analysis to all known and inferred deaths believed to have occurred 2004–2019, the CODs with the largest influence on λ were anthropogenic trauma, anthropogenic drowning, and protozoal disease. In aggregate, anthropogenic CODs had a larger effect on the growth rate than either natural or disease CODs. Possible bias associated with differential carcass detection, recovery, and COD classification are discussed.
KW - Hawaiian monk seal (Neomonachus schauinslandi)
KW - anthropogenic impacts
KW - cause-of-death (COD)
KW - lifetable analysis
KW - population growth rate
KW - toxoplasmosis
KW - undetected mortality
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U2 - 10.1111/mms.12742
DO - 10.1111/mms.12742
M3 - Article
AN - SCOPUS:85090941579
VL - 37
SP - 235
EP - 250
JO - Marine Mammal Science
JF - Marine Mammal Science
SN - 0824-0469
IS - 1
ER -