Port of the Islands 1986-1990 Manatee Distribution Survey Observations

For a full FGDC compliant metadata record, please click here. Aerial distribution surveys are used by marine mammal biologists from FWC 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. Small helicopters may be used instead of fixed wing aircraft in urban areas or where waters are particularly opaque and hovering may be required. Flights are usually six hours long and are most commonly flown every two weeks for two years. The surveys are designed to maximize the manatee counts by concentrating on shallow nearshore waters around the state where manatees and their primary food source, sea grasses, are located. Flight paths curve parallel to the shoreline, and the airplane circles when manatees are spotted until a count of the number of animals in each group is obtained. Offshore waters are usually not surveyed. Dolphin and sea turtle sightings are recorded opportunistically. All aerial data are recorded on paper maps and entered into a GIS shapefile for spatial analysis. GIS is a computer software system for representing data spatially and for conducting spatial analyses. Surveys of Collier County (Port of the Islands) were flown twice a month from January 1986 to December 1990. FWC staff members were observers for these flights. The survey area is divided into three zones: the main basin, Faka Union Canal, and the Channel to the Gulf of Mexico. The main basin consists of ten dredged finger canals and a wider marina area. The Faka Union Canal is a dredged canal that connects the Port of the Islands basin to Faka Union Bay and the Ten Thousand Islands. The Channel to the Gulf of Mexico follows a marked navigation channel that leads approximately 8 km through numerous mangrove islands from the mouth of Faka Union Canal, south across Faka Union Bay to the Gulf of Mexico.若需完整符合FGDC（Federal Geographic Data Committee）规范的元数据记录，请点击此处。美国鱼类与野生动物保护委员会（Florida Fish and Wildlife Conservation Commission, FWC）及其他机构的海洋哺乳动物生物学家会通过航空分布调查确定海牛的季节性分布范围。多数调查采用小型四座高翼飞机（赛斯纳172或182型）执行，飞行高度为500至1000英尺，飞行速度为70至90节。在城市区域或水体透明度极低、需要悬停作业的场景中，可使用小型直升机替代固定翼飞机。单次飞行时长通常为6小时，调查周期一般为两年，且每两周开展一次飞行任务。本调查聚焦于该州内海牛及其主要食物来源海草栖息的浅海近岸水域，以尽可能全面统计海牛种群数量。飞行轨迹沿与海岸线平行的方向弯曲布设，当发现海牛时，飞机会盘旋直至完成对每一群海牛的个体计数。通常不会对远海海域开展调查。调查过程中会对偶遇的海豚与海龟进行记录。所有航空调查数据均先记录于纸质地图，之后录入地理信息系统（Geographic Information System, GIS）的形状文件（shapefile）以开展空间分析。地理信息系统是一种可实现数据空间可视化并开展空间分析的计算机软件系统。1986年1月至1990年12月期间，针对科利尔县（岛屿港）的调查每月开展两次飞行任务，本次飞行的观测员均为FWC工作人员。调查区域划分为三个分区：主盆地、法卡尤恩运河（Faka Union Canal）以及通往墨西哥湾的航道。主盆地包含10条疏浚形成的指状运河及一片更宽阔的游艇码头区域。法卡尤恩运河为一条疏浚运河，连接岛屿港盆地、法卡尤恩湾与万岛群。通往墨西哥湾的航道沿预设导航航线延伸，总长约8公里，途经众多红树林岛屿，从法卡尤恩运河河口向南横跨法卡尤恩湾，最终抵达墨西哥湾。