Fish Counting in the Yakima River System

Bill Bosch, Data Manager

Yakima Klickitat Fisheries Project

Fish counts at Prosser, Roza, and Cowiche Dams in the Yakima River Basin are maintained by the Yakama Nation under the Yakima Klickitat Fisheries Project contract with the Bonneville Power Administration.

Prosser Dam

Fish counting at Prosser is not done in real time 24-hours per day using hired fish counters or automated equipment as it is at many mainstem Columbia River projects. Instead VHS video recording equipment is used at each of the three ladders. Video tapes are collected at least once daily and brought back to Toppenish for viewing and enumeration. The technicians who read the tapes must classify fish by species and try to note whether fish are moving up or back in the ladder so that the same fish are not counted multiple times. The images on the video are not always the best. While it may sound like an easy task, lighting, debris, the way the fish move through the ladder - all of these factors combine to make it more challenging and cumbersome than it sounds. In addition, a portion of the fish on video are sampled for length (the tape is paused and the fish on the screen is measured). This is done so that counts of adults and jacks can be adjusted if necessary post-season. Accurate accounting of the number of jacks in a run is important for historical biological analyses and for forecasting. Once a tape has been viewed and all of the fish on it have been enumerated, the counts for this tape are entered into the video fish count database. In the fall, a portion of the fish pass through the right bank denil trap for sampling. Trapped fish are enumerated in a local database at the trap and later integrated with the video fish count database. The database is queried regularly to produce a report of daily passage and this report is posted to the ykfp.org web site. We try to post updated counts to the web at least twice weekly. Please note that counts for the most recent days in this report may be partial counts as tapes are likely still being read and enumerated for these days. In addition, equipment failures or water conditions may preclude video counting at times during the year. In these cases, available data are reviewed and extrapolations are made to account for video data gaps.

We recognize the desire of the public to have up to date, timely, and accurate fish counts. During times of anticipated heavy fish passage, we try to keep 3 to 4 tape readers on staff and have them work evenings and Saturdays as necessary. In summary, we make every effort to keep fish counts as up to date as possible. Still, events such as very heavy fish counts (it takes longer to process video tapes with more fish on them) or time off for sickness, emergencies, etc. may cause us to fall behind. In these cases, we ask for your patience.

We are continuing to explore other options for more timely fish counting at Prosser such as expanding daily adult PIT detections at Prosser into reasonably accurate total daily counts, sonar devices, and other methods.

Roza Dam

In the spring, all fish are diverted through a trap at Roza to be sampled. A representative portion of the wild/natural return is taken for broodstock to the Cle Elum Supplementation and Research Facility (CESRF) according to a weekly schedule based on expected passage for that week of the run. The remaining wild/natural fish are passed directly back to the river. All returning CESRF fish are externally marked (no adipose fin) and all of these fish are sampled for other marks, lengths, and weight. These data are recorded in a database for research purposes. Fish are then placed in recovery tanks for a short time and returned to the river.

Since all fish at Roza must pass through the trap, they are enumerated and daily counts are entered into a database at the trap. At least once a week, the database is queried to produce a report of daily passage and this report is posted to the ykfp.org web site. During the fall, a combination of video and some occasional trapping is used to produce counts as described above for Prosser Dam counting operations.

Cowiche Dam

The ladder at Cowiche Dam is not ideal for maintaining fish counts. A video system is in place, but due to its configuration, only partial counts are possible. Video counts at Cowiche Dam are maintained in the video fish count database on a lower priority basis.