Interagency Ecological Program San Francisco Estuary Smelt Larva Survey 2009 – 2022

The Interagency Ecological Program San Francisco Estuary Smelt Larva Survey was initiated by the California Department of Fish and Wildlife (CDFW) in 2009 to monitor the distribution and abundance of newly-hatched Longfin Smelt (Spirinchus thaleichthys) in the San Francisco Estuary. Surveys are conducted bi-weekly and sampling begins in December, and continues through March. The surveys sample at fixed locations, stations, from Carquinez Strait through Suisun Bay and into the Sacramento-San Joaquin River Delta. Napa River stations were added in 2014.Each survey consists of 44 stations. At each station, one 10 minute stepped-oblique (bottom to top) tow is made following a prescribed tow schedule. The net is a conical 505 µm mesh lashed to a D shaped frame mounted on skis. Larval fish samples are preserved in the field in 10% Formalin and brought back to the CDFW Stockton Lab for identification to species and enumeration under a microscope. Several types of data are collected at each station in addition to the larval fish sample, including the volume of water sampled by the net, surface water temperature, surface and bottom specific conductance (EC normalized at 25˚C), Secchi disk depth, tow duration, tidal condition, and surface water turbidity.

跨机构生态项目旧金山河口长鳍胡瓜鱼幼体调查（Interagency Ecological Program San Francisco Estuary Smelt Larva Survey）由加利福尼亚州鱼类与野生动物部（California Department of Fish and Wildlife, CDFW）于2009年启动，旨在监测旧金山河口新孵化的长鳍胡瓜鱼（Longfin Smelt，*Spirinchus thaleichthys*）的分布与种群丰度。该调查每两周开展一次，采样工作于每年12月启动，持续至次年3月。采样站位固定，覆盖范围从卡奎内兹海峡（Carquinez Strait）经苏桑湾（Suisun Bay）延伸至萨克拉门托-圣华金河三角洲（Sacramento-San Joaquin River Delta），2014年新增纳帕河（Napa River）站位。单次调查共设置44个采样站位，每个站位均按照既定拖网规程完成一次10分钟的斜向步进拖网（从水底至水面）。拖网为锥形结构，网目尺寸505微米，固定于安装在滑雪板式支架上的D形框架上。幼鱼样本在野外采用10%福尔马林溶液固定，随后送至加利福尼亚州鱼类与野生动物部斯托克顿实验室，在显微镜下开展物种鉴定与个体计数工作。除幼鱼样本外，每个站位还会采集多项配套环境数据，包括网具采水量、表层水温、表层与底层比电导率（25℃下标准化的EC值）、塞氏盘深度、拖网时长、潮汐状况以及表层水体浊度。