Entrainment rates and behavioral patterns of fish can be detected using individual transmitting tags (e.g., radio and acoustic) (Figure 11) or transponding tags (e.g., passive integrated transponder [PIT]) (Figure 12). Transponding tags require an external energy source to activate the tag for data retrieval, and are able to provide information on rate of entrainment and passage route selection. Transmitting tags operate by sending either pulsed or coded signals that can be detected with tracking devices, and are also able to provide information on specific behaviors such as delay and structure avoidance in addition to rate of entrainment and passage route taken. The following reference provides a detailed comparison of various tagging methods:
Nielsen, L. A., and D. L. Johnson. 1983. Fisheries techniques. American Fisheries Society, Bethesda, Maryland.
4.3.3.1 Advantages and disadvantages of approach
Use of individual tags to measure entrainment has advantages and disadvantages relative to the other approaches evaluated, as discussed below:
Advantages
- PIT tags are not dependent on batteries, and can remain inert inside a fish for the duration of its life.
- PIT tags are small (typically 11–28 mm in length and 2.1–3.5 mm in diameter), and can thus be used on juvenile fish.
- PIT tags are relatively inexpensive, and can provide a large sample size.
- Transmitting tags have a relatively large detection range (generally > 1 km).
- Transmitting tags can be used to study impingement rates.
- Transmitting tags can be used at sites where fish recovery is difficult.
- Transmitting tags can provide precise data on the behavior of individual fish, and is not limited by waiting for fish to pass detectors.
- Often multiple evaluations can be conducted from one group of tagged fish, including travel time, movement trajectories, forebay residency time, survival, and habitat use.
- When there are multiple passage routes, it can be determined which route fish used.
- Precision of data is conducive to statistical analysis.
Disadvantages
- PIT-tags have a very limited detection range (approximately 20 cm).
- Transmitting tags are large, expensive, and require extensive handling of fish, thus often limiting sample size. Often only a sub-sample of the population can effectively be tagged, potentially biasing results.
- Transmitting tags are relatively large, and cannot be used on small or juvenile fish.
- Sampling duration using transmitting tags is limited by the battery life.
- In some cases, handling and tagging of fish leads to aberrant behavior.
- Data obtained for tagged fish may not apply to untagged fish.
4.3.3.2 Site-specific considerations and applicability
Many of the advantages and disadvantages of this approach will depend on site-specific considerations, as discussed below:
- Tag type will be dictated by fish size and species, type of data to be collected, habitat utilization, and structure characteristics.
- Acoustic tag detections can be affected by thermal stratification, vegetation, boat noise, and high levels of suspended sediment, and turbulence.
- Radio tags become less effective when fish utilize shallow habitats >5 m deep, or when water conductivity is high.
- In systems with multiple species of interest, often only a few species can be effectively tagged and monitored. However, all tagged individuals provide species-specific data.
- When multiple passage routes are available, the small sample sizes can become highly partitioned, decreasing the power of the analysis.
- Has been applied at numerous hydropower projects 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 Upper Skagit River Hydroelectric Project (FERC Project No. 553), on the Skagit River, Washington; and at the Alabama Power Company Coosa River and Warrior River Hydroelectric Projects (FERC Project Nos. 2146, 2165), on the Coosa and Warrior rivers.
4.3.3.3 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.
Ploskey, G. R., C. R. Schilt, J. Kim, C. W. Escher, and J. R. Skalski. 2003. Hydroacoustic evaluation of fish passage through Bonneville Dam in 2002. Final report PNNL-14356. Prepared by Pacific Northwest National Laboratory, Richland, Washington for U. S. Army Corps of Engineers, Portland, Oregon.Hedgepeth, J., D. Fuhriman and W. Acker. 1999. Fish behavior measured by a tracking radar-type acoustic transducer near hydroelectric dams. Pages 155–171 in M. Odeh, editor. Innovations in fish passage technology. American Fisheries Society, Bethesda, Maryland.
MacLennan, D. N., and E. J. Simmonds. 1992. Fisheries acoustics. Chapman and Hall, London.
Hedgepeth, J. B., D. Fuhriman, G. M. W. Cronkite, Y. Xie, and T. J. Mulligan. 2000. A tracking transducer for following fish movement in shallow water and at close range. Aquatic Living Resources 13: doi:10.1016/S0990-7440(00)01089-5.
Kleinschmidt Associates. 2002. Alabama Power Company Coosa and Warrior River projects. E11 - impingement, entrainment, and turbine mortality study progress report III. Draft report. Prepared by Kleinschmidt Associates Energy and Water Resource Consultants.
Voegeli, F. A., and D. G. Pincock. 1996. Overview of underwater acoustics as it applies to telemetry. E. Baras and J. C. Philippart, editor. Underwater Biotelemetry.
