10,000 Islands 1991-1993 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 Collier County (Ten Thousand Islands) were flown twice a month from January 1991 to November 1993. FWC staff members were observers for these flights. The survey area is part of the Ten Thousand Islands National Wildlife Refuge, Collier-Seminole State Park, Cape Romano-Ten Thousand Islands State Aquatic Preserve and Everglades National Park. There are only two towns within the Ten Thousand Islands: Everglades City and Chokoloskee. The area is a complex landscape of numerous mangrove islands, oyster bars and sand spits separated by tidal creeks and passes. Most of the area is estaurine, with strong tidal influence and freshwater input from numerous creeks and drainage canals.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，会通过航空分布调查来确定海牛的季节性分布范围。多数调查使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，调查周期多为两年，且每两周开展一次飞行。本次调查的设计目标是最大化海牛的统计数量，因此会重点关注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。飞行航线呈与海岸线平行的曲线状，当发现海牛时，飞机会盘旋直至完成对每一群海牛的个体数量统计。远海海域通常不会纳入调查范围。偶遇海豚与海龟的观测记录会被顺带收录。所有航空调查数据都会先记录在纸质地图上，之后录入地理信息系统（GIS）的形状文件（shapefile）中以开展空间分析。地理信息系统（GIS）是一类可对数据进行空间可视化并开展空间分析的计算机软件系统。1991年1月至1993年11月期间，对科利尔县（万岛群岛，Ten Thousand Islands）的调查每月开展两次飞行。本次飞行的观测员均为FWC工作人员。本次调查区域涵盖万岛群岛（Ten Thousand Islands）国家野生动物保护区、科利尔-塞米诺尔州立公园、卡普罗马诺-万岛群岛州级水生保护区以及大沼泽地国家公园的部分区域。万岛群岛范围内仅设有两座城镇：大沼泽地市（Everglades City）与乔科洛斯基（Chokoloskee）。该区域地貌复杂，分布着大量红树林岛屿、牡蛎礁与沙嘴，其间被潮汐水道与航道分隔。区域内大部分为河口生境，受潮汐作用影响显著，同时有众多溪流与排水渠为其注入淡水。