California Department of Fish and Wildlife Enhanced Large Fish Study, San Francisco Estuary, California, 2023 Gillnet Survey

The Enhanced Large Fish Study (ELFS) was established and included in the Interagency Ecological Program (IEP) work plan in 2023 to fill some of the monitoring gap of fishes in the San Francisco Estuary (SFE), California. The fish monitoring of the IEP prior to ELFS primarily consisted of trawl- and seine-based surveys, which generally capture small and/or juvenile fishes due to survey gear and methodologies. In order to more effectively sample the large/adult fish portion of SFE fish communities, the ELFS uses American Fisheries Society experimental gillnets, plus the inclusion of the optional "large fish panel," to sample the waters of the SFE. The experimental gillnets measure 24.4m in length, 1.8m in depth, and includes eight 3m length panels with stretch mesh measurements of 76.2mm, 114.3mm, 50.8mm, 88.9mm, 38.1mm, 127.0mm, 63.5mm, and 101.6mm. The optional large fish panel measures 9.1m by 1.8m in depth and includes three 3m length panels with stretch mesh measurements of 152.4, 177.8, and 203.2mm. The ELFS conducted its first year of sampling in the North Delta, California, in 2023, and will be expanded to the greater Delta and Suisun Bay and Marsh in future sampling years. The ELFS is currently funded as a special study to inform future monitoring, with funding contracted through fiscal year 2026-2027.

增强型大型鱼类研究（Enhanced Large Fish Study，ELFS）于2023年设立并纳入跨机构生态项目（Interagency Ecological Program，IEP）工作计划，旨在填补加利福尼亚州旧金山河口（San Francisco Estuary，SFE）鱼类监测的部分空白。在ELFS启动前，IEP的鱼类监测主要采用拖网和围网调查法，但受调查工具和方法所限，这类调查通常仅能捕获小型及/或幼鱼。为更有效地采集SFE鱼类群落中的大型/成鱼样本，ELFS采用美国渔业学会（American Fisheries Society）的实验性刺网，并可选用‘大型鱼类面板’（large fish panel）对SFE水域进行采样。实验性刺网长24.4米、深1.8米，包含8个3米长的网片，其拉伸网眼尺寸分别为76.2毫米、114.3毫米、50.8毫米、88.9毫米、38.1毫米、127.0毫米、63.5毫米及101.6毫米。可选的大型鱼类面板长9.1米、深1.8米，包含3个3米长的网片，拉伸网眼尺寸分别为152.4毫米、177.8毫米及203.2毫米。ELFS于2023年在加利福尼亚州北三角洲完成了首年采样，并计划在未来采样年度将范围扩展至大三角洲、苏森湾及苏森沼泽。ELFS目前作为专项研究获得资助，旨在为未来监测提供数据支持，资助合同期限至2026-2027财年。