Aerial Surveys of Juvenile Herring, Prince William Sound, 2010-2024, EVOS Herring Program

These data are part of the Herring Program of the Exxon Valdez Oil Spill Trustee Council (EVOSTC), which is a multi-faceted study to determine why herring populations in Prince William Sound (PWS) remain depressed since the early 1990s. Aerial surveys were conducted from 2010 to 2012 during the months of June, July, and August as part of the PWS Herring Survey program by Evelyn Brown (EVOSTC project number 10100132-F). Beginning in 2013 (under EVOSTC projects 12120111-O, 14120111-R, and 16120111-O) surveys have been conducted in June focused on age-1 herring and in July in support of the project entitled Forage Fish Distribution, Abundance, and Body Condition in Prince William Sound, 2012-2015: Gulf Watch Alaska Pelagic Component (EVOSTC projects 12120114-O, 14120114-O, and 16120114-O). Since 2018 the surveys have been supported by the Prince William Sound Regional Citizens' Advisory Council. Flying 1000 feet in the air, following the contours of the Prince William Sound shoreline, schools of juvenile herring are easily identified and measured during the long summer days. Surveying from the air has the benefit of covering a large geographic area while minimizing the disturbance of herring. Aerial surveys cover waters that are too shallow for acoustic survey vessels to access. Each monthly survey takes about 10 to 12 days, 3 to 5 hours each day, in a Cessna 185 float plane. During the course of the survey, the aerial flight tracks, numbers of fish schools, species of fish, school size, marine mammals, marine birds, and notes about unusual oceanographic sightings were recorded electronically and on paper. The fully processed dataset is a comma-separated value (csv) file containing the total number of age-1 herring schools by size (small, medium, large, and x-large) as determined from the 2010-2021 aerial surveys, with a school-size weighted index produced as well. When multiple surveys of an area were conducted only the first set of observations were used in the calculation of numbers of schools. The raw aerial survey data files (csvs, gpx flightlogs, shapefile flightlogs, text notes and photos) are available from the Principal Investigator upon request. Formats of the raw datasets changed over the years of the survey (refer to Usability Report section) and include related files containing time, location, school extent, number of schools, species, herring estimated age, and observations of whales (orca, humpback, minke, grey, and fin). GIS software is necessary to view raw data from all years.

本数据集隶属于埃克森·瓦尔迪兹漏油事件信托理事会（Exxon Valdez Oil Spill Trustee Council, EVOSTC）的鲱鱼研究计划，该项目为多维度系统性研究，旨在探明1990年代初以来威廉王子湾（Prince William Sound, PWS）鲱鱼种群持续衰退的成因。
2010至2012年，由伊夫林·布朗（Evelyn Brown）负责的威廉王子湾鲱鱼调查项目（EVOSTC项目编号：10100132-F）于每年6、7、8月开展航空调查。2013年起，在EVOSTC项目12120111-O、14120111-R及16120111-O支持下，调查调整为每年6月聚焦1龄鲱鱼，7月则服务于题为《2012-2015年威廉王子湾饵料鱼分布、丰度与身体状况：海湾观察阿拉斯加远洋组分》的研究项目（对应EVOSTC项目：12120114-O、14120114-O及16120114-O）。2018年至今，该调查由威廉王子湾区域公民咨询委员会提供资助。
调查人员搭乘塞斯纳185型水上飞机，以1000英尺的高度沿威廉王子湾海岸线轮廓巡航，在夏季昼长时段可便捷识别并计量幼年鲱鱼鱼群。航空调查的优势在于可覆盖广阔地理范围，同时最大限度降低对鲱鱼的惊扰，还能抵达声学调查船无法进入的浅水环境区域。
单次月度调查周期约为10至12天，每日作业时长3至5小时。调查过程中，航空飞行轨迹、鱼群数量、鱼类物种、鱼群规模、海洋哺乳动物、海鸟观测记录及异常海洋学现象备注，均以电子与纸质双渠道留存归档。
经完整处理后的数据集为逗号分隔值（comma-separated value, CSV）文件，包含2010至2021年航空调查中按规模（小型、中型、大型、超大型）划分的1龄鲱鱼鱼群总数，同时附带鱼群规模加权指数。若同一区域开展过多次调查，仅取首次观测结果用于鱼群数量的统计计算。
原始航空调查数据文件（含CSV格式文件、GPX飞行日志、SHP格式飞行日志、文本笔记及影像照片）可向项目首席研究员申请获取。原始数据集的格式在调查周期内历经调整（详见《可用性报告》章节），包含时间戳、地理位置、鱼群范围、鱼群数量、物种、鲱鱼估计年龄以及鲸类观测记录（涵盖虎鲸、座头鲸、小须鲸、灰鲸及长须鲸）。需使用地理信息系统（GIS）软件方可查看所有年份的原始数据。