Earl F. Prentice’s research while affiliated with Oregon State University and other places

A novel application of full-duplex passive integrated transponder (PIT) tag technology was used to investigate movements of individual subyearling Chinook salmon (Oncorhynchus tshawytscha fork length 60mm) into and out of tidally flooded salt marsh habitat in the Salmon River estuary, Oregon, USA. PIT interrogation was effective, with mean tag detection 92%. Salmon movement peaked late during both flood and ebb tide periods, indicating that salmon did not drift passively. Most movements were in the direction of tidal currents, but 20% of individuals entered the channel against the ebbing tide. Individuals occupied the intertidal channel for a median 4.9h and as long as 8.9h per tidal cycle, and few were detected moving when water depth was<0.4m. Some individuals used the channel on multiple successive tidal cycles, and others entered intermittently over periods of up to 109days. Using an individual-based approach, we characterized diversity of juvenile Chinook salmon behavior within a marsh channel, providing insight into the value of such habitats for conservation and restoration of salmon populations.

Since 1984, the National Marine Fisheries Service (NMFS) in cooperation with the Bonneville Power Administration (BPA) has conducted a research project to develop and evaluate technology for passive-integrated-transponder tags (PIT tags) throughout the Columbia River Basin (CRB). Work conducted as part of this project between October 2000 and September 2002 (FY01 and FY02) was divided into seven individual elements, which are covered separately in this report. The efforts by personnel associated with this project have produced and will continue to produce products that aid resource stakeholders in assessing the effectiveness of actions taken to enhance the survival of juvenile and adult salmonids. These products and their uses include: (1) Survival and migration timing information on stocks to evaluate water management strategies and fish passage/collection facilities; (2) Data needed for the management and restoration of salmonids and other fish stocks listed under the Endangered Species Act (ESA); (3) Information required for the management of multiple species in a variety of habitats; and (4) Tools that enable fisheries researchers and managers to address previously unanswerable questions and critical uncertainties These products are also used in genetic, physiology, behavior, and captive broodstock research on endangered species. The continued development of PIT-tag technology will enable researchers and fisheries managers to address issues expressed in both of NMFS biological opinions for operation of the Federal Columbia River Power System (FCRPS)(NMFS 1995a, 2000) and the proposed Snake River Recovery Plan (NMFS 1995b; tasks 2.1.d, 2.3.b.4, 2.4.a, 2.6.c.2, and 2.9.d).

To evaluate whether stress-response indicators in blood plasma (BP) are similarly reflected in the peritoneal fluid (PF) white sturgeon Acipenser transmontanus were stressed by a 30 min air exposure and pH, PCO2, osmolality, cortisol, glucose and lactate levels measured. Changes in certain stress indicators in the BP (pH, PCO2, osmolality and glucose) also occurred in the PF, while stressor-induced changes in cortisol and lactate were restricted to the BP. Data suggest that PF is a modified ultrafiltrate of the blood and potentially a useful indicator of animal stress.

We tested the performance of two stationary interrogation systems designed for detecting the movement of fish with passive integrated transponder (PIT) tags. These systems allowed us to determine the direction of fish movement with high detection efficiency and high precision in a dynamic stream environment. We describe an indirect method for deriving an estimate for detection efficiency and the associated variance that does not rely on a known number of fish passing the system. By using six antennas arranged in a longitudinal series of three arrays, we attained detection efficiencies for downstream- and upstream-moving fish exceeding 96% during high-flow periods and approached 100% during low-flow periods for the two interrogation systems we tested. Because these systems did not rely on structural components, such as bridges or culverts, they were readily adaptable to remote, natural stream sites. Because of built-in redundancy, these systems were able to perform even with a loss of one or more antennas owing to dislodgement or electrical failure. However, the reduction in redundancy resulted in decreased efficiency and precision and the potential loss of ability to determine the direction of fish movement. What we learned about these systems should be applicable to a wide variety of other antenna configurations and to other types of PIT tags and transceivers.

We developed a prototype detection system with increased reading range for passive integrated transponder (PIT) tags. The system eliminates the need to route juvenile salmonids to sampling and collection facilities for detection and allows fisheries management greater flexibility in safely bypassing juvenile salmonids at dams. This technology can be applied to PIT-tag studies elsewhere, especially those directed at recovery of threatened and endangered salmonid populations. The system exceeded the intended goal of 95% tag-reading efficiency and yielded reading efficiencies near 100% for the four antennas combined. In tests using juvenile steelhead Oncorhynchus mykiss and subyearling Chinook salmon O. tshawytscha, the system worked as designed under a variety of release times and densities. Both direct and indirect methods were used to evaluate the system. The direct method used a known number of tagged fish released at a specific location and compared that number to the number of unique tag codes read. Using this method, over 98% reading efficiency was obtained under all test conditions. The indirect method relied upon a statistical comparison of reading performance between antennas during the juvenile migration season. This method showed that the system efficiency ranged between 99.5% and 100%.

During winter 2001, the U.S. Army Corps of Engineers (Corps) and Bonneville Power Administration (BPA) installed a prototype orifice-based PIT-tag interrogation system into the Washington Shore Ladder at Bonneville Dam (BWSL). Detectors were installed into 12 weirs: 4 downstream (Weirs 334-337) and 8 upstream (Weirs 352-359) from the fish release point (i.e., the exit ladder for the Adult Fish Facility). NOAA Fisheries (National Marine Fisheries Service--NMFS) tagged and released salmonids during 2001 to determine tag-reading efficiencies for different salmonid populations. Data analyses focused on the upper eight weirs. The 2001 tagging results for spring chinook salmon indicated that having detectors in four consecutive weirs would have been sufficient to yield a reading efficiency of 95%. The BWSL orifice-based system performed well until the coho and fall chinook salmon migrations began. Coho and fall chinook salmon appeared to use the weir overflows, and thus avoid detection, at much higher rates than biologists expected. During 2001, technology advances led to the development of significantly larger antennas than had been available earlier, and thus it was possible to build antennas of approximately 2 x 6 ft. Consequently, it became feasible to design interrogation systems for ladder locations where all fish would have to go through the antennas and thus could not avoid detection by using the weir overflows (Fig. 1). Destron Technologies by Digital Angel designed a prototype interrogation system with two antennas that was installed into the counting-window area in the Oregon Ladder at McNary Dam, where its performance could then be directly compared to that of the orifice-based system in the same ladder. Although the orifice-based systems appeared less effective than the fisheries community wanted for fall chinook and coho salmon, the decision was made to proceed with installations planned for Bonneville and McNary Dams because valuable data would still be collected. During the winter of 2002, the Corps and BPA installed PIT-tag interrogation systems into the Bradford Island and Cascades Island Fish Ladders at Bonneville Dam and into the Washington and Oregon Ladders at McNary Dam. Like BWSL in 2001, these ladders had eight weirs (16 orifices) outfitted with fiberglass antennas. Douglas County Public Utility District also installed an orifice-based system into its ladders at Wells Dam, but they were able to use weirs with no overflow sections wherein all fish had to swim through the orifice antennas. Thus, 2002 was the first year that the fisheries community had PIT-tag detection of adult salmonids at Bonneville, McNary, Wells, and Lower Granite Dams (Fig. 2). This overview will provide information on how well the systems at Bonneville and McNary Dams performed.

Data collected on juvenile salmonids tagged with passive integrated transponder (PIT) tags as they migrate seaward through the Columbia River Basin provide fisheries managers and resource agencies with valuable information to evaluate the effectiveness of current management actions and restoration strategies. The development of new technology to route PIT-tagged fish through multiple alternative pathways as they pass through the interrogation systems at the fish bypass/monitoring facilities at hydroelectric dams provides another valuable real-time tool to monitor and evaluate the migration, passage, and survival of PIT-tagged juvenile salmonids in the basin. The authors describe the current computer program and gate-control technology for routing fish, and provide detailed descriptions of three new types of fish-diversion gates. The comparative advantages and disadvantages of each gate are discussed. The prototype of a fourth diversion gate, with only one moving part, is also described.

A multiyear program to evaluate the technical and biological feasibility of a new identification system for salmonids established between the Bonneville Power Administration (BPA) and the National Marine Fisheries Service (NMFS) in 1983.

In the spring of 1996 and 1997, a prototype 400 kHz flat-plate (pass-by) passive integrated transponder tag interrogation (PIT tag) system was installed at the terminus of the downstream migrant (DSM) channel of the Bonneville Dam First Powerhouse, located on the Columbia River. The system was designed to interrogate previously PIT tagged juvenile salmonids migrating down the Columbia River without interfering with the traditional subsampling of fish passing through the facility. In addition, the design enables fish of virtually any size, and debris, to pass over the system's antennas without the port restrictions imposed by traditional pass-through PIT tag interrogation systems. We describe the fish facility in addition to the flat-plate system and its operation. The system tag reading efficiency was evaluated during 1996 and 1997 using a direct method based on the release of known numbers of tagged test fish and an indirect statistical procedure based on tagged run-at-large fish. The results showed that PIT tag reading efficiency during both years using the direct method averaged 97%, while that using the statistical procedure averaged 99% for the dual multiplexed antenna array. During the 1996 and 1997 field seasons 4371 and 14 733 fish, respectively, were recorded. Daily system functionality was monitored using stick tests (i.e., the passing of PIT tagged sticks across the antenna array).

The assumption that marking does not alter the vulnerability of fish to a visual predator was examined. Similar numbers of age-0 steelhead Oncorhynchus mykiss were tagged with binary-coded-wires, tagged with passive integrated transponders, freeze branded, marked with fingerling tags, or left unmarked. All were subjected to age-1 steelhead predators for 24 h in 2.4-m-diameter circular tanks filled with clear well water. Twice as many marked as unmarked age-0 steelhead prey were eaten. There was no significant survival difference among the four marked treatment groups, which suggested that in the laboratory the trauma associated with marking is more important than mark type. We conclude that marking may effect postrelease survival and recommend that mark–recapture experiments be used to empirically determine and correct for differences in survival of marked and unmarked fish.