Publication Date:
2022-05-26
Description:
© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Boys, R. M., Oliveira, C., Perez-Jorgeo, S., Prieto, R., Steiner, L., & Silva, M. A. Multi-state open robust design applied to opportunistic data reveals dynamics of wide-ranging taxa: The sperm whale case. Ecosphere, 10(3), (2019):e02610, doi:10.1002/ecs2.2610.
Description:
Capture–mark–recapture methods have been extensively used to estimate abundance, demography, and life history parameters of populations of several taxa. However, the high mobility of many species means that dedicated surveys are logistically complicated and expensive. Use of opportunistic data may be an alternative, if modeling takes into account the inevitable heterogeneity in capture probability from imperfect detection and incomplete sampling, which can produce significant bias in parameter estimates. Here, we compare covariate‐based open Jolly‐Seber models (POPAN) and multi‐state open robust design (MSORD) models to estimate demographic parameters of the sperm whale population summering in the Azores, from photo‐identification data collected opportunistically by whale‐watching operators and researchers. The structure of the MSORD also allows for extra information to be obtained, estimating temporary emigration and improving precision of estimated parameters. Estimates of survival from both POPAN and MSORD were high, constant, and very similar. The POPAN model, which partially accounted for heterogeneity in capture probabilities, estimated an unbiased super‐population of ~1470 whales, with annual abundance showing a positive trend from 351 individuals (95% CI: 234–526) in 2010 to 718 (95% CI: 477–1082) in 2015. In contrast, estimates of abundance from MSORD models that explicitly incorporated imperfect detection due to temporary emigration were less biased, more precise, and showed no trend over years, from 275 individuals (95% CI: 188–404) in 2014 to 367 (95% CI: 248–542) in 2012. The MSORD estimated short residence time and an even‐flow temporary emigration, meaning that the probability of whales emigrating from and immigrating to the area was equal. Our results illustrate how failure to account for transience and temporary emigration can lead to biased estimates and trends in abundance, compromising our ability to detect true population changes. MSORD models should improve inferences of population dynamics, especially when capture probability is low and highly variable, due to wide‐ranging behavior of individuals or to non‐standardized sampling. Therefore, these models should provide less biased estimates and more accurate assessments of uncertainty that can inform management and conservation measures.
Description:
We acknowledge IFAW for providing photo‐identification data from the early period of the study (1987–1993), Biosphere Expeditions and clients of Whale Watch Azores for making data collection possible. We thank Sara Magalhães, Tiago Sá, João Medeiros, Yves Cuenot, Pablo Chevallard Navarro, and numerous volunteers that over the years helped with data collection and organization of the photo‐identification catalogue. We are deeply grateful to Gary White, Bill Kendall, Jim Hines, James Nichols, Paul Conn, and Olivier Gimenez for offering guidance and advice on CMR modeling. We thank Jonathan Gordon for his comments on an earlier version of the manuscript. We are thankful to the three anonymous reviewers for providing very helpful comments.
This work was supported by Fundação para a Ciência e Tecnologia (FCT), Azores 2020 Operational Programme, and Fundo Regional da Ciência e Tecnologia (FRCT) through research projects FCT‐Exploratory project (IF/00943/2013/CP1199/CT0001), WATCH IT (Acores‐01‐0145‐FEDER‐000057), and MISTIC SEAS II (GA11.0661/2017/750679/SUB/ENV.C2) co‐funded by FEDER, COMPETE, QREN, POPH, ESF, Portuguese Ministry for Science and Education, and EU‐DG/ENV. The Azores 2020 Operational Programme is funded by the community structural funds ERDF and ESF. We also acknowledge funds provided by FCT to MARE, through the strategic project UID/MAR/04292/2013. Rebecca M Boys is supported by an Estagiar L scholarship, Cláudia Oliveira by a research assistant contract from WATCH IT and Mónica A Silva by an FCT‐Investigator contract (IF/00943/2013), and Rui Prieto by an FCT postdoctoral grant (SFRH/BPD/108007/2015).
Mónica A Silva conceptualized the project, acquired funding, administered, and supervised the project. Lisa Steiner, Cláudia Oliveira, Rebecca M Boys, and Mónica A Silva involved in data curation. Rebecca M Boys, Mónica A Silva, Sergi Pérez‐Jorge, and Cláudia Oliveira involved in formal analysis, investigation, and methodology. Rebecca M Boys preparation and visualization of the data. Rebecca M Boys, Mónica A Silva, Sergi Pérez‐Jorge, Rui Prieto wrote the original draft of the manuscript. Rebecca M Boys, Mónica A Silva, Rui Prieto, Sergi Pérez‐Jorge, Cláudia Oliveira, and Lisa Steiner wrote, reviewed, and edited the manuscript.
Keywords:
abundance
;
capture–mark–recapture
;
mobile taxa
;
multi‐state open robust design model
;
opportunistic data
;
photo‐identification
;
POPAN model
;
population dynamics
;
sperm whales (Physeter macrocephalus)
;
survival
;
temporary emigration
;
transients
Repository Name:
Woods Hole Open Access Server
Type:
Article
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