USGS is working with partners to understand how the federally protected Florida manatee population changes over time and responds to threats.
The Science Issue and Relevance: Understanding how the federally threatened Florida manatee population changes over time and responds to threats is important for managers of state and federal management agencies, particularly U.S. Fish and Wildlife Service (USFWS) and the Florida Fish and Wildlife Conservation Commission (FWC).
Methodology for Addressing the Issue: We have developed several estimators of abundance that use aerial count data from aircraft and unmanned aerial systems surveys and account for observation errors during surveys. USGS Patuxent (in collaboration with USGS WARC, Florida Fish and Wildlife Conservation Commission (FWC), and US Fish and Wildlife Service (USFWS)) is leading the development of a population projection model, the Core Biological Model (CBM), which was developed to project manatee abundance, the probability of quasi extinction, and evaluate threats in the long term (e.g., 60 years). It is an important tool for managers to assess the status of the manatee population and major threats. However, this model was not designed to quantify the effect of specific events (e.g., red tide event of 2013 or cold mortality events of 2010), it is also not suited to make inference about historic trends. Therefore, we are working on developing an integrated population model (IPM) that would provide critical information that is complementary to the CBM. This IPM model is led by FWC (in collaboration with USGS WARC and USGS Patuxent).
Future Steps:
The IPM model would allow managers to (1) better understand the impact of specific events on the population; (2) track historical changes in the population; (3) set up a framework to increase accuracy and precision of key parameters used in the CBM; (4) evaluate scientific hypotheses relevant to the population dynamics of manatees; and (5) could ultimately help with the prioritization of monitoring information (e.g., establish frequency and intensity of monitoring).
Related Products:
Martin, J., Royle, J. A., MacKenzie, D.I., H. H. Edwards, M. Kery, Gardner, B. (2011) Accounting for non- independent detection when estimating abundance of organisms with a hierarchical Bayesian approach. Methods in Ecology and Evolution, 2, 595–601.
Dorazio, R.M., Martin, J., Edwards, H.H. (2013) Estimating abundance while accounting for rarity, correlated behavior, and other sources of variation in counts. Ecology, 94, 1472-1478.
Martin, J., Edwards, H.H., Bled, F., Fonnesbeck, C.J., Dupuis, J.A., Gardner, B. (2014) Estimating upper bounds for occupancy and number of manatees in areas potentially affected by oil from the Deepwater Horizon oil spill. PLoS ONE 9, e91683.
Martin, J., Edwards, H.H., Fonnesbeck, C.J., Koslovsky, S.M., Harmak, C, Dane, T. (2015). Combining information for monitoring at large spatial scales: first statewide abundance estimate of the Florida manatee. Biological Conservation, 186, 44-51.
Martin, Julien, Runge, M.C., Flewelling, L.J., Deutsch, C.J., and Landsberg, J.H., 2017, An expert elicitation process to project the frequency and magnitude of Florida manatee mortality events caused by red tide (Karenia brevis): U.S. Geological Survey Open-File Report 2017–1132, 17 p., https://doi.org/10.3133/ofr20171132.
Runge, M.C., Sanders-Reed, C.A., Langtimm, C.A., Hostetler, J.A., Martin, J., Deutsch, C.J., Ward-Geiger, L.I., and Mahon, G.L., 2017, Status and threats analysis for the Florida manatee (Trichechus manatus latirostris), 2016: U.S. Geological Survey Scientific Investigation Report 2017–5030, 40 p., https://doi.org/10.3133/sir20175030.
Hostetler, J. A., Edwards, H. H., Martin, J., and Schueller, P. 2018. Updated Statewide Abundance Estimates for the Florida Manatee. Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute Technical Report No. 23.
Demographic and Population Models to Assess Recovery and Status of the Endangered Florida Manatee
Below are publications associated with this project.
Updated statewide abundance estimates for the Florida manatee
An expert elicitation process to project the frequency and magnitude of Florida manatee mortality events caused by red tide (Karenia brevis)
Status and threats analysis for the Florida manatee (Trichechus manatus latirostris), 2016
Estimating abundance while accounting for rarity, correlated behavior, and other sources of variation in counts
Below are partners associated with this project.
- Overview
USGS is working with partners to understand how the federally protected Florida manatee population changes over time and responds to threats.
Manatee and calf (Public domain.) The Science Issue and Relevance: Understanding how the federally threatened Florida manatee population changes over time and responds to threats is important for managers of state and federal management agencies, particularly U.S. Fish and Wildlife Service (USFWS) and the Florida Fish and Wildlife Conservation Commission (FWC).
West Indian manatees congregate around a warm-water source in Florida. (Public Domain) Methodology for Addressing the Issue: We have developed several estimators of abundance that use aerial count data from aircraft and unmanned aerial systems surveys and account for observation errors during surveys. USGS Patuxent (in collaboration with USGS WARC, Florida Fish and Wildlife Conservation Commission (FWC), and US Fish and Wildlife Service (USFWS)) is leading the development of a population projection model, the Core Biological Model (CBM), which was developed to project manatee abundance, the probability of quasi extinction, and evaluate threats in the long term (e.g., 60 years). It is an important tool for managers to assess the status of the manatee population and major threats. However, this model was not designed to quantify the effect of specific events (e.g., red tide event of 2013 or cold mortality events of 2010), it is also not suited to make inference about historic trends. Therefore, we are working on developing an integrated population model (IPM) that would provide critical information that is complementary to the CBM. This IPM model is led by FWC (in collaboration with USGS WARC and USGS Patuxent).
Future Steps:
The IPM model would allow managers to (1) better understand the impact of specific events on the population; (2) track historical changes in the population; (3) set up a framework to increase accuracy and precision of key parameters used in the CBM; (4) evaluate scientific hypotheses relevant to the population dynamics of manatees; and (5) could ultimately help with the prioritization of monitoring information (e.g., establish frequency and intensity of monitoring).
Related Products:
Martin, J., Royle, J. A., MacKenzie, D.I., H. H. Edwards, M. Kery, Gardner, B. (2011) Accounting for non- independent detection when estimating abundance of organisms with a hierarchical Bayesian approach. Methods in Ecology and Evolution, 2, 595–601.
Dorazio, R.M., Martin, J., Edwards, H.H. (2013) Estimating abundance while accounting for rarity, correlated behavior, and other sources of variation in counts. Ecology, 94, 1472-1478.
Martin, J., Edwards, H.H., Bled, F., Fonnesbeck, C.J., Dupuis, J.A., Gardner, B. (2014) Estimating upper bounds for occupancy and number of manatees in areas potentially affected by oil from the Deepwater Horizon oil spill. PLoS ONE 9, e91683.
Martin, J., Edwards, H.H., Fonnesbeck, C.J., Koslovsky, S.M., Harmak, C, Dane, T. (2015). Combining information for monitoring at large spatial scales: first statewide abundance estimate of the Florida manatee. Biological Conservation, 186, 44-51.
Martin, Julien, Runge, M.C., Flewelling, L.J., Deutsch, C.J., and Landsberg, J.H., 2017, An expert elicitation process to project the frequency and magnitude of Florida manatee mortality events caused by red tide (Karenia brevis): U.S. Geological Survey Open-File Report 2017–1132, 17 p., https://doi.org/10.3133/ofr20171132.
Runge, M.C., Sanders-Reed, C.A., Langtimm, C.A., Hostetler, J.A., Martin, J., Deutsch, C.J., Ward-Geiger, L.I., and Mahon, G.L., 2017, Status and threats analysis for the Florida manatee (Trichechus manatus latirostris), 2016: U.S. Geological Survey Scientific Investigation Report 2017–5030, 40 p., https://doi.org/10.3133/sir20175030.
Hostetler, J. A., Edwards, H. H., Martin, J., and Schueller, P. 2018. Updated Statewide Abundance Estimates for the Florida Manatee. Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute Technical Report No. 23.
- Science
Demographic and Population Models to Assess Recovery and Status of the Endangered Florida Manatee
Population models developed by USGS are the primary decision-support tools used for status assessments, and rely on estimates of adult survival and reproduction rates from mark-recapture studies. - Publications
Below are publications associated with this project.
Updated statewide abundance estimates for the Florida manatee
Knowing how many manatees live in Florida is critical for conservation and management of this threatened species. Martin et al. (2015) flew aerial surveys in 2011–2012 and estimated abundance in those years using advanced techniques that incorporated multiple data sources. We flew additional aerial surveys in 2015–2016 to count manatees and again applied advanced statistical techniques to estimateAuthorsJeffrey A. Hostetler, Holly H. Edwards, Julien Martin, Paul SchuellerAn expert elicitation process to project the frequency and magnitude of Florida manatee mortality events caused by red tide (Karenia brevis)
Red tides (blooms of the harmful alga Karenia brevis) are one of the major sources of mortality for the Florida manatee (Trichechus manatus latirostris), especially in southwest Florida. It has been hypothesized that the frequency and severity of red tides may increase in the future because of global climate change and other factors. To improve our ecological forecast for the effects of red tidesAuthorsJulien Martin, Michael C. Runge, Leanne J. Flewelling, Charles J. Deutsch, Jan H. LandsbergStatus and threats analysis for the Florida manatee (Trichechus manatus latirostris), 2016
Trichechus manatus (West Indian manatee), especially T. m. latirostris, the Florida subspecies, has been the focus of conservation efforts and extensive research since its listing under the Endangered Species Act of 1973. To determine the status of, and severity of threats to, the Florida manatee, a comprehensive revision and update of the manatee Core Biological Model was completed and used to peAuthorsMichael C. Runge, Carol A. Sanders-Reed, Catherine A. Langtimm, Jeffrey A. Hostetler, Julien Martin, Charles J. Deutsch, Leslie I. Ward-Geiger, Gary L. MahonEstimating abundance while accounting for rarity, correlated behavior, and other sources of variation in counts
The class of N-mixture models allows abundance to be estimated from repeated, point count surveys while adjusting for imperfect detection of individuals. We developed an extension of N-mixture models to account for two commonly observed phenomena in point count surveys: rarity and lack of independence induced by unmeasurable sources of variation in the detectability of individuals. Rarity increaseAuthorsRobert M. Dorazio, Juulien Martin, Holly H. Edwards - Partners
Below are partners associated with this project.