James D. Kieffer

Limits to exhaustive exercise in fish

Exercise to exhaustion leads to severe metabolic, acid-base and ionic changes in fish. It has been shown that several abiotic and biotic factors can limit burst exercise performance and the recovery process in fish. This article reviews the importance of body size, temperature, fasting/starvation and training on the ability of fish to perform and recover from exhaustive exercise. It is concluded that the constraints placed on a fish prior to and following exercise reflects the large intra-specific variability in the physiological response to exercise in fish.

Physiological Significance of the Weigh-In during Live-Release Angling Tournaments for Largemouth Bass

Abstract In the current study, we simulated different components of a live-release angling tournament (angling, live-well confinement, and weigh-in) to determine the relative physiological significance of these tournament components for largemouth bass Micropterus salmoides. Our results indicated that depletions of white muscle energy stores and accumulations of muscle lactate (i.e., a large metabolic disturbance) are the most important consequences of live-release angling tournaments for largemouth bass. This study also showed that there are two distinct components of a live-release tournament that cause a metabolic disturbance in largemouth bass: angling and the weigh-in. While the physiological consequences of angling are already well understood, this is the first study to show that the weigh-in portion of a live-release tournament also causes a large anaerobic disturbance in largemouth bass. In our simulation, the weigh-in resulted in a 75% decrease in white muscle phosphocreatine, a 46% decrease in A...

Perspective--Exercise in fish: 50+years and going strong.

Swimming in fish has garnered the attention of researchers for more than 50years. Research has focused on the mechanisms that fish utilize during exercise, fuel use patterns, recovery dynamics and the effects of abiotic and biotic factors on fish exercise physiology. Research direction has been influenced both by technology (e.g., availability of telemetry devices and access to swim flumes) and environmental changes (e.g., global warming and pollution). In addition, researchers have begun to examine the interplay between swimming physiology and behaviour. As part of the 50th Anniversary of Comparative Physiology and Biochemistry, this perspective examines the history of fish exercise research, and some of the individuals who have made significant contributions.

The physiological response of diploid and triploid brook trout to exhaustive exercise

Using triploidy as an experimental model, we examined whether cell size limits the post-exercise recovery process in fish. Because triploids generally possess larger cells, which could affect many physiological and biochemical processes, we hypothesized that triploids would take longer to recover from exhaustive exercise compared to diploids. To test this, we measured plasma lactate, glucose and osmolality, and white muscle energy stores (glycogen, phosphocreatine and ATP) and lactate before and immediately following exhaustive exercise and during recovery at 2 and 4 h post-exercise. In addition, oxygen consumption and ammonia excretion rates were determined before and after exhaustive exercise. Overall, diploid and triploid brook trout showed similar metabolic responses exercise, but plasma osmolality, white muscle lactate, white muscle ATP and post-exercise oxygen consumption rates recovered earlier in triploids compared to diploids. The results of this study suggest that the characteristic larger cell size of triploidy does not limit the physiological response to, or recovery from, exhaustive exercise.

Physiology and survival of triploid brook trout following exhaustive exercise in warm water

We investigated the effects of chronic high temperature (19 °C) on the post-exercise recovery processes in diploid and triploid brook trout. For these experiments, we measured the metabolic fuels glycogen, phosphocreatine (PCr) and ATP in the white muscle, and the muscle [lactate], plasma [lactate], plasma [glucose], plasma osmolality and blood hemoglobin levels before, following, and during recovery from exhaustive exercise. Although both diploids and triploids responded metabolically to exercise, the magnitude of the response was different between ploidies. In particular, triploids used less PCr and more glycogen than diploids. Also, the patterns of metabolic recovery were different between diploids and triploids. In addition to triploid trout having difficulty utilizing anaerobic pathways, these fish took longer to recover from the metabolic disturbance. This lack of recovery of the metabolites at warmer temperatures in triploids might be a contributing factor to the increased mortality of these fish: 9 of 10 triploids died within 4 h of exposure to 19 °C, whereas none of the diploids died.

The Effects of an Acute Temperature Change on the Metabolic Recovery from Exhaustive Exercise in Juvenile Atlantic Salmon (Salmo salar)

This research examined the influence of acute changes of water temperature on the recovery processes following exhaustive exercise in juvenile Atlantic salmon (Salmo salar). White muscle phosphocreatine (PCr), ATP, lactate, glycogen, glucose, pyruvate, plasma lactate, and plasma osmolality were measured during rest and at 0, 1, 2, and 4 h following exhaustive exercise in fish acclimated and exercised at 12°C and acutely exposed to either 6°C or 18°C water during recovery. An acute exposure to 6°C water during the recovery period resulted in a severe reduction of metabolic recovery in salmon. However, metabolites such as muscle PCr and ATP and plasma lactate recovered very quickly (2–4 h) in fish acutely exposed to 18°C during recovery. Overall, differences exist when postexercise metabolite levels are compared between acclimated fish and those fish acutely exposed to different water temperatures (either higher or lower). Taken together, the findings of the acute experiments suggest that at some point following exercise fish may seek warmer environments to speed the recovery process. However, the relationship between behavioural thermoregulation and recovery following exhaustive exercise in fish is not well understood.

Juvenile atlantic and shortnose sturgeons (family: Acipenseridae) have different hematological responses to acute environmental hypoxia.

Experiments were conducted to determine the behavioral and physiological responses to acute hypoxic challenges in Atlantic (Acipenser oxyrinchus) and shortnose (Acipenser brevirostrum) sturgeons. We measured the ventilatory rate following a 45‐mmHg hypoxic challenge, as well as a variety of hematological parameters, including O2 transport and hormonal, ionic, and metabolic variables, following a 1‐h exposure to either 75‐ or 30‐mmHg hypoxic challenges. Compared to fish in normoxic conditions (Pwo2 150 mmHg), juveniles of both species increased their ventilatory rate by approximately 40% when exposed to a 1‐h challenge at 45 mmHg Pwo2. Hematological variables (e.g., hematocrit, hemoglobin, and Na+ and Cl− levels) did not change substantially following a 1‐h challenge at 75 mmHg Pwo2. Conversely, a severe hypoxic challenge of 30 mmHg caused changes in several hematological variables (e.g., whole blood glucose and plasma cortisol and lactate levels). Most of these hematological parameters returned to prehypoxic levels within 2 h. Severe environmental hypoxia elicited the same basic pattern of response in both species; however, maximal plasma lactate levels were higher in Atlantic sturgeons, and maximal cortisol levels were higher in shortnose sturgeons. Whether these species differences are related to dissimilar hypoxia‐tolerance, ecological, and/or endocrinological characteristics between these two species is not entirely clear.

The Effect of Capture, Handling, and Tagging on Hematological Variables in Wild Adult Lake Sturgeon

Abstract We measured hematocrit and plasma osmolality, cortisol, lactate, glucose, and chloride in wild lake sturgeon Acipenser fulvescens after gill-net capture (24-h sets) and multiple bouts of brief (2–3-min) air exposure during removal from nets and again during measurement and tagging procedures. Our objective was to evaluate the physiological consequences associated with capture, handling, and tagging activities commonly employed during mark–recapture studies and to determine whether blood chemistry values moved toward a resting state after a 3-d recovery period. Lake sturgeon that were caught during spring tagging activities showed plasma cortisol, glucose, lactate, osmolality, and chloride levels similar to those exhibited by maximally stressed lake sturgeon in published laboratory studies. After the 3-d recovery period, all physiological stress indicators had approached a nonstressed state and the values were similar to those previously reported for resting lake sturgeon. It appears that capture–...

The influence of flume length and group size on swimming performance in shortnose sturgeon Acipenser brevirostrum

The main objectives of this study were to determine optimal methodologies to assess the general swimming performance of juvenile shortnose sturgeon Acipenser brevirostrum. Swimming densities (group v. individual swimming) and flume length (2 v. 1 m) were altered to verify if any of those variables affected performance (i.e. time to fatigue) during critical swimming (U(crit)) and endurance tests. Results for both U(crit) and endurance swimming were not significantly different between fish swum in groups of five or fish swum individually. The U(crit) values, however, were c. 22% higher for fish swum in a longer flume. Although swimming fish in groups did not improve swimming performance, group swimming lowered the variance of the data. Results also reveal that juvenile A. brevirostrum may not possess an ability to swim at high speeds (i.e. burst phase) for long periods.

The Effects of Temperature and Swimming Speed on Instantaneous Fuel Use and Nitrogenous Waste Excretion of the Nile Tilapia

The effects of acclimation temperature (30°, 20°, and 15°C) and swimming speed on the aerobic fuel use of the Nile tilapia (Oreochromis niloticus; 8–10 g, 8–9‐cm fork length) were investigated using a respirometric approach. As acclimation temperature was decreased from 30°C to 15°C, resting oxygen consumption (Mo2) and carbon dioxide excretion (Mo2) decreased approximately twofold, while nitrogenous waste excretion (ammonia‐N plus urea‐N) decreased approximately fourfold. Instantaneous aerobic fuel usage was calculated from respiratory gas exchange. At 30°C, resting Mo2 was fueled by 42% lipids, 27% carbohydrates, and 31% protein. At 15°C, lipid use decreased to 21%, carbohydrate use increased greatly to 63%, and protein use decreased to 16%. These patterns at 30°C and 15°C in tilapia paralleled fuel use previously reported in rainbow trout acclimated to 15°C and 5°C, respectively. Temperature also had a pronounced effect on critical swimming speed (UCrit). Tilapia acclimated to 30°C had a UCrit of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape