East Bay Municipal Utility District Project Research Project

Movement of hatchery and wild Mokelumne River steelhead through the Central Valley, California

We will examine the gross movement patterns of Mokelumne River steelhead trout (O. mykiss), of hatchery and river origin, through the lower Mokelumne River and Delta system using ultrasonic telemetry. Ten receiver stations have been set up from the base of Camanche Dam through tidal water of the Mokelumne River delta. The stations are meant to augment the station grid already put in place through the Sacramento San Joaquin river system to help understand habitat use and movement of various steelhead life histories as well as the differences between hatchery and river fish.

To compare and contrast movement and gross habitat use of hatchery and river steelhead of various live stages. The data gathered from this project will be used to:

  1. Describe reach-specific rates of movement of hatchery and river steelhead from the lower Mokelumne River to the coastal ocean.
  2. Explain some of the variation in reach-specific movement by examining life stage (parr; silvery parr; smolt; adult; post spawn adult), fish origin (hatchery –vs- river) and time of year.

We surgically implanted Vemco V9 tags into the peritoneal cavity of 57 steelhead smolts raised at the Mokelumne River Fish Hatchery (MRFH), 2 post-yearling hatchery steelhead that had residualized in the river ,2 MRFH kelts, and 54 river-produced steelhead (often referred to as “wild”) of various lifestages (>160 mm FL); and Vemco V13 tags into 5 post-spawn MRFH steelhead (kelt) during February and March 2007, and one V13 into a wild adult steelhead. Tagged fish were held for one week. Hatchery smolts were transported by tank to tidal water and released adjacent to hatchery release locations. River fish and post-yearling residual hatchery steelhead were released at original capture locations throughout the non-tidal Mokelumne River (within 20 km of Camanche Dam). Kelts were released to the river adjacent to the MRFH.

By networking with other monitoring programs, we can gain a better understanding of migratory timing and routes of hatchery and river steelhead of various life stages.

With the support of UC Davis, we have deployed all 10 monitors from Camanche Dam to the mouth of the Mokelumne River. This includes lower Georgiana Slough; the mouth of Little Potato Slough at Tower Park, the entrance of Snodgrass Slough, and the mouth of the Cosumnes River. Steelhead tagging has been completed for the 2007 season with the exception of approximately 5 – 8 steelhead to be tagged later in Spring 2007. We have downloaded all stages once so far and are presently working with UC Davis to integrate our databases. We are supporting a UC Santa Cruz doctoral candidate in a manual tracking study of these fish.