Injury and mortality rates through a specified structure can be determined by experimentally releasing a batch of fish through a given structure and then recovering these fish at the outlet of the structure. Experimental fish may be released either with or without a tag; however, tags such as balloon and transponding tags (e.g., radio and acoustic) will increase the probability for recovery. The HI-Z Turb’N Tag is a “balloon tag” consisting of small deflated plastic balloons that are externally mounted to test fish (Figure 13). After the fish are released, the balloons will inflate after a predetermined time period, which will bring the fish to the surface where they can be recaptured. Other types of batch marks (e.g. fin-clips, dye, inkjet, or coded wire tags) are also useful for denoting individuals for test releases, although they do not allow as precise of an analysis as individual tags.

4.3.4.1 Advantages and disadvantages of approach

Use of experimental releases of fish to measure entrainment has advantages and disadvantages relative to the other approaches evaluated, as discussed below:

Advantages

• Balloon tags can be used on fish that are sensitive to handling.
• Assessment of delayed mortality is possible.
• Ability to recapture nearly all fish released provides a statistically rigorous estimate of entrainment mortality and injury rate.
• Multiple trials using different passage routes, species, size classes, and project operations can be used to test differences in injury and mortality rates.

Disadvantages

• Testing wild fish is often not possible, limiting analysis to surrogates, usually hatchery fish.
• Sample sizes required for adequate statistics may limit the number of trails conducted.

4.3.4.2 Site-specific considerations and applicability

Many of the advantages and disadvantages of this approach will depend on site-specific considerations, as discussed below:

• Recovery of fish may be difficult in tailraces where boat access is limited or unsafe.
• Has been applied at numerous dams on the Columbia River, including the Bonneville Hydroelectric Project (owned by the USACE, Portland District) and the Dalles Hydroelectric Project (FERC Project No. 7076); and at the Willamette Hydroelectric Project (FERC Project No. 2233) on the Willamette River.

4.3.4.3 Selected references

EPRI (Electric Power Research Institute). 1992. Fish entrainment and turbine mortality review and guidelines. Final Report. Research Project 2694-01; EPRI TR-101231. Palo Alto, California.

Ferguson, J. W., G. M. Matthews, R. L. McComas, R. F. Absolon, D. A. Brege, M. H. Gessel, and L. G. Gilbreath. 2004. Passage of adult and juvenile salmon through federal Columbia River power system dams. NOAA Technical Memorandum. NOAA Fisheries, Fish Ecology Division, Fish Ecology Division, Northwest Fisheries Science Center.

Normandeau Associates. 2001. Fall 2000 evaluation of juvenile spring chinook salmon downstream migration at the Willamette Falls Project under two passage scenarios. Final Report. Prepared for Portland General Electric Company, Portland, Oregon, Blue Heron Paper Company, Oregon City, Oregon, and Willamette Falls Project Fisheries, Aquatics, and Terrestrial Workgroup.

Normandeau Associates. 2001. Feasibility of estimating direct mortality and injury on juvenile salmonids passing the Dalles Dam Spillway during high discharge. Contract No. DACW68-96-D-0003, Task Order DT04.

Normandeau Associates, Inc., J. R. Skalski, and Mid Columbia Consulting, Inc. 1996.Potential effects of spillway flow deflectors on fish condition and survival at the
Bonneville Dam, Columbia River. Report to U.S. Army Corps of Engineers, Portland District, Portland, Oregon.

4.3.3 Individual tagging

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4.3.5 Sensor fish device