Acoustic Telemetry and Benthic Video Lander Studies of Dungeness Crab in the Columbia River Estuary and Nearshore Zone

The Columbia River estuary and the adjacent nearshore zone are important habitat for Dungeness crab (Cancer magister), and these areas support valuable commercial and recreational fisheries. The estuary sustains high densities of juvenile crabs and is thought to function as a nursery, while larger crabs and especially females are believed to migrate to more saline nearshore habitat to mate and release brooded larvae. However, little is documented about these crab migrations or indeed crab distributions or movements between habitats in general. One possible impact on crab populations is dredge operations in the mouth of the Columbia and sediment deposition events in the nearshore designed to aid beach nourishment. To learn more about crab movements and the effects of dredge depositions, we have been using acoustic telemetry to investigate Dungeness crab movements in Baker Bay, a large lateral bay near the mouth of the Columbia River. Additionally, we are using acoustic tracking and benthic video imagery to investigate effects of dredge deposition events on crabs in the nearshore zone. This presentation will report methods and results from some of the acoustic tracking and video experiments.