St. Johns, Flagler, & Volusia counties 1991-1993 Manatee Distribution Survey Theoretical Flight Path

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. Surveys are flown along a standardized, theoretical flight route, which was designed to cover all likely manatee habitats in the study area. This "theoretical flight path" indicates the area that was covered during each survey, but it may not be the actual flight route flown on every survey. GPS tracklines recorded during surveys may be available for some flights. The survey area includes the coastal, estuarine, and riverine waters of St. Johns, Flagler and Volusia counties. The St. Johns River or tributaries were not included. The survey extended from the Duval-St. Johns county line south to Mosquito Lagoon at the Volusia-Brevard county line. The water bodies included in the survey are Tolomato, Guana, Matanzas, San Sebastian, Tomoka and Halifax rivers; Turnbull Bay; Salt Run; Spruce Creek and Palm Coast canal systems.美国鱼类与野生动物保护局（FWC）及其他机构的海洋哺乳动物生物学家，会借助航空分布调查（aerial distribution surveys）来确定海牛（manatee）的季节性分布范围。绝大多数调查采用四座小型上单翼飞机（塞斯纳（Cessna）172或182）开展，飞行高度为500至1000英尺，航速控制在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（fixed wing aircraft）。调查按照标准化的理论航线执行，该航线的设计目标是覆盖研究区域内所有潜在的海牛栖息地。这条“理论飞行路径”标明了每次调查所覆盖的水域范围，但实际执行的飞行航线未必与理论航线完全一致。部分航班会留存调查期间记录的GPS航迹数据。本次调查区域涵盖圣约翰斯（St. Johns）、弗莱格勒（Flagler）与沃卢西亚（Volusia）三县的沿岸、河口及河流水域，但圣约翰斯河及其支流不在调查范围内。调查范围北起杜瓦尔-圣约翰斯县界，南至沃卢西亚-布雷瓦德（Brevard）县界的蚊子泻湖（Mosquito Lagoon）。本次调查涵盖的水体包括托洛马托河（Tolomato）、瓜纳河（Guana）、马坦萨斯河（Matanzas）、圣塞瓦斯蒂安河（San Sebastian）、托莫卡河（Tomoka）与哈利法克斯河（Halifax）；特恩布尔湾（Turnbull Bay）；盐溪（Salt Run）；云杉溪（Spruce Creek）以及棕榈海岸运河系统（Palm Coast canal systems）。