title: Estimating upper bounds for occupancy and number of manatees in areas potentially affected by oil from the Deepwater Horizon oil spill.
abstract: The explosion of the Deepwater Horizon drilling platform created the largest marine oil spill in U.S. history. As part of the Natural Resource Damage Assessment process, we applied an innovative modeling approach to obtain upper estimates for occupancy and for number of manatees in areas potentially affected by the oil spill. Our data consisted of aerial survey counts in waters of the Florida Panhandle, Alabama and Mississippi. Our method, which uses a Bayesian approach, allows for the propagation of uncertainty associated with estimates from empirical data and from the published literature. We illustrate that it is possible to derive estimates of occupancy rate and upper estimates of the number of manatees present at the time of sampling, even when no manatees were observed in our sampled plots during surveys. We estimated that fewer than 2.4% of potentially affected manatee habitat in our Florida study area may have been occupied by manatees. The upper estimate for the number of manatees present in potentially impacted areas (within our study area) was estimated with our model to be 74 (95%CI 46 to 107). This upper estimate for the number of manatees was conditioned on the upper 95%CI value of the occupancy rate. In other words, based on our estimates, it is highly probable that there were 107 or fewer manatees in our study area during the time of our surveys. Because our analyses apply to habitats considered likely manatee habitats, our inference is restricted to these sites and to the time frame of our surveys. Given that manatees may be hard to see during aerial surveys, it was important to account for imperfect detection. The approach that we described can be useful for determining the best allocation of resources for monitoring and conservation.
authors.affiliation: Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, St Petersburg, Florida, United States of America.
authors.forename: Julien
authors.initials: J
authors.lastname: Martin
authors.affiliation: Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, St Petersburg, Florida, United States of America.
authors.forename: Holly H
authors.initials: HH
authors.lastname: Edwards
authors.affiliation: Patuxent Wildlife Research Center, United States Geological Survey, Laurel, Maryland, United States of America; Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado, United States of America.
authors.forename: Florent
authors.initials: F
authors.lastname: Bled
authors.affiliation: Department of Biostatistics, Vanderbilt University, Nashville, Tennessee, United States of America.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Fonnesbeck
authors.affiliation: Laboratoire de Statistique et Probabilités, Université Paul Sabatier, Toulouse, France.
authors.forename: Jérôme A
authors.initials: JA
authors.lastname: Dupuis
authors.affiliation: Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina, United States of America.
authors.forename: Beth
authors.initials: B
authors.lastname: Gardner
authors.affiliation: Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, St Petersburg, Florida, United States of America.
authors.forename: Stacie M
authors.initials: SM
authors.lastname: Koslovsky
authors.affiliation: Dauphin Island Sea Lab, Dauphin Island, Alabama, United States of America; University of South Alabama, Mobile, Alabama, United States of America.
authors.forename: Allen M
authors.initials: AM
authors.lastname: Aven
authors.affiliation: Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, St Petersburg, Florida, United States of America.
authors.forename: Leslie I
authors.initials: LI
authors.lastname: Ward-Geiger
authors.affiliation: Dauphin Island Sea Lab, Dauphin Island, Alabama, United States of America; University of South Alabama, Mobile, Alabama, United States of America.
authors.forename: Ruth H
authors.initials: RH
authors.lastname: Carmichael
authors.affiliation: Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, St Petersburg, Florida, United States of America.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Fagan
authors.affiliation: Sea to Shore Alliance, 4411, Sarasota, Florida, United States of America.
authors.forename: Monica A
authors.initials: MA
authors.lastname: Ross
authors.affiliation: Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, St Petersburg, Florida, United States of America.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Reinert
mesh_terms: D000407:Alabama; D000818:Animals; D017753:Ecosystem; D004784:Environmental Monitoring; D005431:Florida; D005843:Geography; D008922:Mississippi; D059392:Petroleum Pollution; D011795:Surveys and Questionnaires; D020455:Trichechus / Q000502:physiology*