Martin and St Lucie counties 2010-2012 Manatee Distribution Survey Observations

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 five 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 Martin and St. Lucie County were flown twice a month from August 2010 to July 2012. FWC staff members were observers for these flights. The survey area includes Ft. Pierce Inlet, Indian River, St. Lucie Inlet, St. Lucie River (North and South Fork), North Fork, Loxahatchee River, Jupiter Sound, and Hobe Sound.来自佛罗里达鱼类与野生动物保护委员会（FWC）及其他机构的海洋哺乳动物生物学家，借助航空分布调查确定海牛的季节分布范围。 多数调查采用小型四座高翼飞机（赛斯纳172或182）开展，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5小时，调查周期普遍为两年，且飞行频次为每两周一次。本次调查的设计目标是最大化海牛的统计数量，因此重点覆盖全州范围内的浅海近岸水域——这里是海牛及其主要食物来源海草的栖息区域。 飞行轨迹呈与海岸线平行的弧形，当发现海牛时，飞机会盘旋直至完成对该群体内所有个体的计数。远海海域通常不纳入调查范围。调查过程中若偶遇海豚与海龟，也会对其目击情况进行记录。 所有航空调查数据均会先记录于纸质地图，随后录入地理信息系统（GIS）的形状文件（shapefile）以开展空间分析。地理信息系统（GIS）是一类用于以空间形式呈现数据并开展空间分析的计算机软件系统。 2010年8月至2012年7月期间，针对马丁县与圣卢西县的调查每月开展两次飞行，任务观测员均为FWC工作人员。本次调查区域涵盖皮尔斯堡水道（Ft. Pierce Inlet）、印第安河（Indian River）、圣卢西水道（St. Lucie Inlet）、圣卢西河（南北支流）、北支流、洛哈奇河（Loxahatchee River）、朱庇特湾（Jupiter Sound）以及霍比湾（Hobe Sound）。