Monitoring juvenile Chinook salmon outmigration using rotary screw traps on Butte Creek

The California Department of Fish and Wildlife (CDFW) conducts
juvenile salmonid emigration monitoring on Butte Creek at the
Parrot-Phelan Diversion Dam near Chico, California. Monitoring is
conducted annually from October through June utilizing an 8-ft
diameter rotary screw trap (RST) and a diversion screen trap (DST).
Data from this monitoring is used to estimate juvenile spring-run
Chinook salmon (Oncorhynchus tshawytscha) abundance and passage,
identify alevin emergence timing, document juvenile size at
emigration, and document rearing and emigration patterns. This data
will also be used to inform the development of a juvenile production
estimate (JPE) for spring-run Chinook salmon in the Sacramento River
Watershed as required by Condition of Approval 7.5.2 of Incidental
Take Permit No. 2081-2019-006-00 (ITP) issued by CDFW to California
Department of Water Resources (DWR) for the long-term operation of
the State Water Project. Salmonid data collected from the Butte
Creek RST, among other datasets, is also used by the Salmon
Monitoring Team (SaMT) to understand the movement of juvenile salmon
in the Sacramento River Watershed to estimate the number of
winter-run and spring-run Chinook salmon that have entered the
Sacramento-San Joaquin Delta (Delta). SaMT is a real-time operations
monitoring team required by Condition of Approval 8.1.2 of the ITP
which meets weekly from October through June, to provide advice for
real-time management of SWP operations to DWR, CDFW, and the Water
Operation Management Team (WOMT) to minimize take of winter-run and
spring-run Chinook salmon in the Delta.

Note: data within the current year’s monitoring season are
considered provisional.

加利福尼亚州鱼类与野生动物局（California Department of Fish and Wildlife, CDFW）在加利福尼亚州奇科市附近的帕罗特-费伦分水坝（Parrot-Phelan Diversion Dam）的比尤特溪（Butte Creek）开展幼年鲑科鱼类洄游监测。该监测每年10月至次年6月开展，采用直径8英尺的旋转式螺杆诱捕器（rotary screw trap, RST）与分水屏诱捕器（diversion screen trap, DST）进行数据采集。

本次监测所获数据可实现多项研究目标：一是估算春季洄游型奇努克鲑（Oncorhynchus tshawytscha）的种群丰度与过坝通过率；二是确定其鱼卵孵化出苗的时间节点；三是记录洄游幼体的体型规格；四是梳理其育幼与洄游的行为模式。此外，该数据还将用于支撑萨克拉门托河流域春季洄游型奇努克鲑幼体产量估算（juvenile production estimate, JPE）模型的开发工作，以满足加利福尼亚州鱼类与野生动物局向加利福尼亚州水资源部（California Department of Water Resources, DWR）签发的第2081-2019-006-00号附带捕捞许可（Incidental Take Permit, ITP）中第7.5.2条审批条件的相关要求，该许可用于州水资源工程（State Water Project, SWP）的长期运营管理。

比尤特溪旋转式螺杆诱捕器采集的鲑科鱼类数据，与其他多套数据集一同被鲑鱼监测团队（Salmon Monitoring Team, SaMT）用于分析萨克拉门托河流域幼鲑的移动规律，进而估算进入萨克拉门托-圣华金河三角洲（Delta）的冬季洄游型与春季洄游型奇努克鲑的种群数量。鲑鱼监测团队是依据上述附带捕捞许可第8.1.2条审批条件设立的实时运营监测团队，于每年10月至次年6月每周召开工作会议，为加利福尼亚州水资源部、加利福尼亚州鱼类与野生动物局及水资源运营管理团队（Water Operation Management Team, WOMT）提供州水资源工程实时运营的决策建议，以最大限度降低萨克拉门托-圣华金河三角洲内冬季、春季洄游型奇努克鲑的意外捕捞损失。

备注：本年度监测季内的相关数据均视为临时数据。