Volusia County 2023-2024 Manatee Distribution Survey Observations

Aerial distribution surveys are used by marine mammal biologists from Florida Fish & Wildlife Conservation Commission-Fish and Wildlife Research Institute (FWC-FWRI) and other agencies to determine the seasonal distribution of manatees. Most surveys are conducted from small, four-seat, high-winged airplanes (Cessna 172 or 182) flying at a height of 500-1000 ft at a speed of 70-90 kts. This survey was conducted by one aircraft mostly following historical flight paths used for past county-wide distribution surveys. However, some changes were made to shorten the flight route or to cover areas not flown in previous paths. See trackline metadata for details of flight path modifications. Flight paths generally curved parallel to the shoreline, and the airplane circled when manatees were spotted until a count of the number of animals in each group was obtained. Circling was limited to 3 passes unless a group was unusually large and aerial photos were used in some cases to confirm counts. Sightings data were recorded on paper maps and entered into a GIS shapefile for spatial analysis using NAIP 2021 - 2023 imagery and recorded flight paths as a reference. GIS is a computer software system for representing data spatially and for conducting spatial analyses. Counts presented in this dataset have not been corrected for detection bias (either perception or availability) and the absence of sightings in an area does not mean that no animals were present. This dataset includes recorded manatee sightings from 21 surveys flown on the following dates: 2 and 23 August 2023; 1 and 25 September 2023; 18 and 26 October 2023; 21 and 30 November 2023; 19 December 2023; 10 and 23 January 2024; 22 and 27 February 2024; 1 and 18 April 2024; 2 and 24 May 2024; 17 and 26 June 2024; 11 and 26 July 2024. FWC staff members were primary observers for these flights, and dual observers (two observers, one in the front seat and one in the rear seat) were present on some or all of survey flights. The survey area includes coastal areas of Volusia County, Florida from the Flagler-Volusia County line to the Volusia-Brevard County line at the southern end of Mosquito Lagoon. Some areas along the planned flight path may have been partially surveyed or not surveyed at all due to air traffic, weather, or other constraints present during individual surveys.佛罗里达鱼类与野生动物保护委员会-鱼类与野生动物研究所（FWC-FWRI）及其他机构的海洋哺乳动物生物学家，会借助航空普查确定海牛的季节性分布。绝大多数普查任务采用小型四座上单翼飞机（塞斯纳172或182）执行，飞行高度为500-1000英尺，航速70-90节。本次普查由单架飞机执行，航线主要沿用过往全县范围分布普查的历史飞行路径，但为缩短航程或覆盖以往航线未涉及的区域，对部分航线进行了调整，具体航线修改细节请参阅航线元数据。 飞行航线通常与海岸线平行弯曲，当发现海牛群时，飞机将盘旋直至完成该群动物数量的计数。除非群体规模异常庞大，否则盘旋次数限制为3次；部分场景下会使用航空照片辅助确认计数结果。 目击数据首先记录于纸质地图，之后导入地理信息系统（GIS）形状文件，以2021-2023年NAIP（National Agriculture Imagery Program）影像及记录的飞行航线为参考开展空间分析。地理信息系统是一类用于空间化呈现数据并开展空间分析的计算机软件系统。 本数据集所呈现的海牛计数结果，未针对检测偏差（包括感知偏差与可获得性偏差）进行校正；某一区域未出现目击记录，并不代表该区域不存在海牛。 本数据集包含21次飞行普查的海牛目击记录，对应的飞行日期分别为：2023年8月2日、23日；2023年9月1日、25日；2023年10月18日、26日；2023年11月21日、30日；2023年12月19日；2024年1月10日、23日；2024年2月22日、27日；2024年4月1日、18日；2024年5月2日、24日；2024年6月17日、26日；2024年7月11日、26日。 本次飞行的主要观察员均来自FWC工作人员，部分或全部普查航班采用双观察员配置（即前排座位与后排座位各一名观察员）。 普查区域涵盖佛罗里达州沃卢西亚县的沿海海域，北至弗莱格勒-沃卢西亚县界，南至蚊子泻湖南端的沃卢西亚-布雷瓦德县界。由于单次普查期间遭遇空中交通、恶劣天气或其他限制因素，规划航线中的部分区域可能仅完成部分普查，或完全未开展普查。