Broward and Miami-Dade counties 1988-1990 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 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 Broward and northern Dade County were flown twice a month from January 1988 to March 1990. FWC staff members were observers for these flights. The survey area includes the southern portion of Palm Beach County, the length of Broward County and the northern half of Dade County. The survey followed the Intracoastal Waterway (ICW) from Lake Boca Raton in southern Palm Beach County, southward along the ICW in Broward County and ended at Kings Bay on the northwestern shore of Biscayne Bay in Dade County.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，通过航空分布调查确定海牛的季节性分布格局。绝大多数调查采用四座上单翼小型飞机（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。在城区水域、水体透明度极低且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，常规调查周期为两年，调查频次为每两周一次。 本次调查以最大化海牛计数准确性为核心目标，重点覆盖全州范围内海牛及其主要食物来源海草栖息的浅海近岸水域。飞行轨迹沿海岸线平行弯曲布设，当观测到海牛群时，飞机将盘旋直至完成该群体个体数量的完整统计。远海海域通常不在调查覆盖范围内。 调查过程中偶遇的海豚与海龟观测记录将被机会性收录。所有航空调查数据均先记录于纸质地图，随后录入地理信息系统（GIS）形状文件（shapefile）以开展空间分析。地理信息系统（GIS）是一类可实现数据空间可视化与空间分析的计算机软件系统。 1988年1月至1990年3月期间，针对布劳沃德县与戴德县北部的调查飞行频次为每月两次，本次调查的观测员均为FWC工作人员。 调查范围涵盖棕榈滩县南部区域、布劳沃德县全域以及戴德县北部半区。本次调查沿内陆水道（ICW）布设航线：从棕榈滩县南部的博卡拉顿湖出发，沿布劳沃德县境内的内陆水道向南行进，最终终止于戴德县比斯坎湾西北岸的金斯湾。