Flagler & St. Johns counties 2005-2007 Manatee Distribution Survey Observations

Aerial distribution surveys are used by marine mammal biologists from FWC and other agencies to determine the seasonable 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 knots. 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 3 to 5 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 not usually 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. Surveys of Flagler and St. Johns Counties were flown twice a month from October 2005 to September 2007. FWC and St. Johns County Habitat Conservation Plan staff members were observers for these flights. The survey area included the Bulow Creek in Volusia County, Atlantic Coast, Intracoastal Waterway of Flagler and St. Johns Counties.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，开展航空分布调查以明确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，飞行高度设定为500至1000英尺，航速保持在70至90节。在城市区域或水体浑浊、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3至5小时，调查频次多为每两周一次，持续两年。本调查聚焦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，以最大化海牛的统计数量。飞行航线沿海岸线呈平行弯曲布局，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。远海水域通常不在本次调查的覆盖范围内。调查过程中会顺带记录偶遇的海豚及海龟观测记录。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。2005年10月至2007年9月期间，针对弗莱格勒县与圣约翰斯县的调查频次调整为每月两次。本次飞行的观测员由FWC及圣约翰斯县栖息地保护计划的工作人员担任。调查区域涵盖沃卢西亚县的布卢湾溪、大西洋沿岸，以及弗莱格勒县与圣约翰斯县的沿岸内陆航道 (Intracoastal Waterway)。