Fyke traps have been used around the globe for centuries to catch a variety of aquatic species. These traps have funnel-shaped openings that narrow toward the interior of the structure. Fish follow the funnel into the trap and, once inside, have difficulty finding the opening to escape because they tend to stay near the outer walls of the trap. Fyke traps have been used on the Sacramento River since the 1950s to estimate salmon and steelhead runs, and later to estimate striped bass populations. More recently, FISHBIO has fabricated and deployed fyke traps for multiple research projects, including monitoring striped bass and other non-native fishes on the San Joaquin River.
We construct fyke traps as large cylinders of steel pipe and cyclone fencing that typically measure 10 ft. in diameter and 20 ft. in length. The design includes two fykes that feed one into the other, with the innermost funnel leading to the trap livewell. Access doors near the rear of the trap make it possible to remove fish for sampling while keeping the trap partially submerged. The traps are mounted on cables attached to levees alongside the river, and can be easily deployed and retrieved using a trailer-mounted winch to raise and lower the trap to its ideal fishing position. We have also incorporated a PIT tag antenna into a fyke trap design to passively monitor for tagged fish when water temperatures or other conditions prohibit handling fish directly.