In 2023, FISHBIO designed, fabricated, and installed the first Incline Plane Trap (IPT) in California. This custom trap was built for use in a fish reintroduction study implemented by the California Department of Water Resources, ICF, and the Pacific States Marine Fisheries Commission, and was intended for trapping and monitoring out-migration juvenile spring run Chinook salmon (Oncorhynchus tshawytscha). Project partners commissioned the fabrication of the Incline Plane trap to provide alternative options for catching juvenile salmon at various flow conditions, particularly during low flow periods when RST operation can be inefficient or impossible.
FISHBIO Staff and project partner staff working together to install the incline plane trap.
Utilizing information from a 1994 Alaska Fishery Research Bulletin, and insight from discussions with a fisheries management group using an IPT in Alaska, FISHBIO designed an aluminum and stainless steel IPT for capturing out-migrating juvenile salmonids. An IPT can be suspended between two pontoons in a barge-like structure (much like a RST) or may be set on the stream bed and anchored to shore with cable in shallow water. The trap functions best in streams with slow water velocity, which acts to gently direct downstream migrating fish up a stainless steel mesh ramp, and then guides them over an adjustable weir plate and into a live-box. Fish are held safely in the live box until project staff can retrieve them for processing and release. FISHBIO also constructed steel guide panels to use in tandem with the IPT to help funnel fish from a wider area into the trap. While the panels were developed for the Incline Plane Trap, they can also be used with RSTs, demonstrating their versatility in various applications. The design approach used by the FISHBIO FABLAB tailored the trap to project needs, and construction of the trap itself took approximately six weeks.
With assistance from project partners, FISHBIO successfully installed the IPT on the North Fork of the Feather River below Chester Diversion Dam. FISHBIO staff also trained on-site staff on trap installation, operation, maintenance, and removal. The IPT represents a useful tool for monitoring juvenile salmon numbers in systems where other gears may not be feasible, and traps similar to this one may have useful applications in many streams throughout California and beyond.
Header image: An Incline Plane Trap and a RST next to each other.
