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The Problem Pacific lampreys (Lampetra tridentata) in the Columbia River Basin have declined to only a remnant of their pre-1940's populations. One factor that could be detrimental to lamprey production is the amount
Pacific lampreys enter streams over extended periods as much as 12 months before they spawn and, because feeding ceases when they enter freshwater, have a finite amount of energy reserves with which to migrate upstream, produce gametes, and complete their life history. An excessive use of energy in negotiating fishways during their upstream migration could limit or stop the complex physiological processes necessary for sexual maturation and successful reproduction. This research is funded under Military Interdepartmental Purchase Request (MIPR) W66QKZ20162191 with the Corps of Engineers (COE). Objectives
Methodology
Objective 1. Determine the critical swimming speed and prolonged swimming performance of radio-tagged and untagged Pacific lamprey at different temperatures and fish sizes. We will first determine the critical swimming speed (Ucrit) of radio-tagged and untagged lampreys following methods originally described by Brett (1964). This will allow us to examine the effects of surgery and tagging on swimming performance and will also provide estimates of the swimming capabilities of these fish. We will assess the effects of different water temperatures and fish sizes on prolonged swimming using a natural range of conditions normally found in the Columbia River. Objective 2. Examine the relationship between telemetered electromyograms (EMG's), oxygen consumption, and physiological indicators of stress in Pacific lampreys during prolonged swimming. We will use swimming respirometry to determine the relationship between metabolic rate (i.e., oxygen consumption) and EMG's (see Lucas et al. (1993) for a complete review of methodology). Experiments will be carried out over a range of temperatures likely to be experienced by these fish in the wild. Data will be analyzed to determine the nature of the relationship between oxygen consumption and the EMG's. Blood samples will be assayed for various indicators of stress, including but not limited to such factors as pH, hematocrit, plasma lactate, glucose, and ions. We will also assess the relationship between classical indicators of stress and metabolic rate. Objective 3. Using telemetered electromyograms and laboratory-derived information, assess the condition and metabolic costs of wild Pacific lampreys as they move through the upstream fish passage facilities at Bonneville Dam. We will monitor physiological function and movement of EMG-tagged fish as they negotiate the fishway. Telemetered physiological data, in conjunction with our laboratory-derived relationships, will be used to estimate oxygen consumption of fish swimming up the fishway. We will then compare oxygen consumption of fish swimming up the passage facility to that of resting laboratory fish and those subjected to our respirometry trials to determine the metabolic cost (i.e., the stressful effects) of negotiating upstream fishway passage. Objective 4. Document sex steroid and other physiological profiles for Pacific lampreys on an annual basis. To describe physiological profiles of Pacific lampreys on an annual basis, we will hold a group of lampreys for one year under ambient conditions in the laboratory and sample them repeatedly for blood and morphological indicators of reproductive development. Certain steroids and other plasma constituents will be assayed and levels plotted over time to assess the changes during a one-year period. In addition, we will sample blood from lampreys migrating upstream through the fish passage facilities at Bonneville Dam. We hope to obtain samples from fish that successfully passed the dam and those that did not. Highlights and Key Findings
To date, we have: (1) documented consistent and distinct EMG output from resting lampreys and those swimming at defined speeds using externally attached and surgically implanted EMG radio transmitters; (2) using Blazka-type swimming respirometers, we estimated the critical swimming speed (Ucrit) of Pacific lampreys with a mean total length of about 63 cm to be (mean ± SD) 1.4 ± 0.1 body lengths·s-1 (86.2 ± 7.5 cm·s-1 ) at 15ºC; (3) documented physiological responses of Pacific lampreys to exhaustive exercise, including decreases in blood pH and muscle glycogen and increases in hematocrit and plasma and muscle lactate; (4) estimated the active rates of oxygen consumption for lampreys swimming at defined speeds at three temeperatures; and (5) completed one year of assessing annual physiological and morphological changes in lampreys held in the lab. Physiological factors assayed included the sex steroids estradiol and progesterone, thyroxine, plasma protein, glucose, and triglycerides. These data are currently being analyzed. The EMG data from Pacific lampreys indicate that this technology has promise for evaluating energy use of lampreys in the wild. Our estimates of Ucrit for these fish are the first reported for this species and substantiate the notion that lampreys are poor swimmers compared to many teleosts. Our physiological results indicate that Pacific lampreys show metabolic dysfunction after exhaustive exercise, but recover quickly from a single exposure to such a stressor. However, questions regarding the responses of lampreys to multiple bouts of exhaustive stress, which seems likely to occur during passage at dams, remain unanswered. Where Are We Headed In 2003 For FY03, we will conduct the final analysis of our data collected in FY 2002 and will continue work to describe sex steroid and other physiological profiles of Pacific lampreys. This research is useful to resource managers and others involved in efforts aimed at improving Pacific lamprey production in the Columbia River Basin. Evaluating the metabolic costs to Pacific lampreys of migrating through fishways is a critical step in the overall rehabilitation of this important species. Assessment of the potential detrimental effects of exhaustive stress on reproductive performance of Pacific lampreys will be an important ecological aspect of stress in fish. Collectively, our results should allow managers to make more informed decisions regarding if and how fishways will have to be modified to accommodate migrating Pacific lampreys. Project Contact Jennifer Bayer Email: jennifer_bayer@usgs.gov Publications |
