Interagency Ecological Program: Zooplankton and water quality data in the San Francisco Estuary collected by the Summer Townet and Fall Midwater Trawl monitoring programs.

The Interagency Ecological Program’s (IEP) Summer Townet Survey (STN) and Fall Midwater Trawl (FMWT) are two long-term monitoring projects conducted by the California Department of Fish and Wildlife (CDFW) to monitor fish abundance and distribution trends in the San Francisco Estuary (SFE) since 1959 and 1967, respectively. Starting in 2005, zooplankton monitoring was added and paired with fish tows to investigate food availability for young fishes. Food limitation has been a long-term issue and a focus of the Pelagic Organism Decline (POD) studies that began in 2005. By 2011, STN routinely conducted zooplankton monitoring at 40 stations, and FMWT at 32 stations in the upper SFE from Carquinez Strait to the Sacramento Deep Water Ship Channel and into the South Delta. STN samples every other week from June to August and FMWT samples once monthly from September to December. Both projects collect mesozooplankton samples using a modified Clarke-Bumpus (CB) net to target copepods and cladocerans, and FMWT also samples macrozooplankton (i.e. mysids and amphipods) using a mysid net. Flowmeters are used to measure the volume sampled to determine zooplankton catch per unit effort. Environmental variables such as water temperature, turbidity, secchi, and electrical conductivity are collected with each zooplankton sample. Concurrent fish and zooplankton tows conducted by STN and FMWT have allowed for comparisons of fish diet to the available zooplankton prey at the time of collection.

跨机构生态项目（Interagency Ecological Program, IEP）的夏季托网调查（Summer Townet Survey, STN）与秋季中层拖网调查（Fall Midwater Trawl, FMWT）是由加利福尼亚州鱼类与野生动物局（California Department of Fish and Wildlife, CDFW）开展的两项长期监测项目，分别自1959年和1967年起持续监测旧金山河口（San Francisco Estuary, SFE）内的鱼类丰度与分布趋势。2005年起，两项监测均新增浮游动物监测环节，并与鱼类拖网采样配对开展，以探究幼鱼的食物可获得性。食物限制问题长期存在，亦是2005年启动的浮游生物衰退（Pelagic Organism Decline, POD）研究的核心议题。截至2011年，夏季托网调查在旧金山河口上游区域（从卡奎内兹海峡至萨克拉门托深水航道并延伸至南三角洲）的40个站位常规开展浮游动物监测，秋季中层拖网调查则在该区域的32个站位开展此项工作。夏季托网调查的采样周期为每两周一次，采样时段为6月至8月；秋季中层拖网调查则为每月一次，采样时段为9月至12月。两项项目均使用改良型克拉克-邦普斯（Clarke-Bumpus, CB）网采集中型浮游动物样本，以桡足类与枝角类为目标类群；此外秋季中层拖网调查还使用糠虾网采集大型浮游动物（即糠虾与端足类）。采样过程中使用流量计记录采样体积，以计算单位捕捞努力量下的浮游动物捕获量。每次采集浮游动物样本的同时，还会记录水温、浊度、塞氏盘透明度与电导率等环境变量。夏季托网调查与秋季中层拖网调查同步开展的鱼类与浮游动物拖网采样，使得研究人员能够将鱼类食谱与采样时刻的可获取浮游动物猎物进行比对分析。