. (2003). The effect of temperature on swimming performance and oxygen consumption in adult sockeye (Oncorhynchus nerka) and coho (O. kisutch) salmon stocks. J. Exp. Biol. 206,[3239][3240][3241][3242][3243][3244][3245][3246][3247][3248][3249][3250][3251] In both the on-line and printed versions of this paper, some of the equations in the legends to Figs 2-4 were printed incorrectly.On page 3245, in the legend to Fig.·2, the two equations should read:M O 2 routine =2.12+0.09e 0.18t (ambient; broken line) and M O 2 routine =1.39+0.54e 0.08t (adjusted; solid line).On page 3246, in the legend to Fig.·3 The authors apologise for any inconvenience these errors may have caused.Temperature has been coined the 'ecological master factor' for fish (Brett, 1971), and important physiological functions such as growth, swimming performance and active metabolic rate can have species-specific temperature optima that are near a species-preferred or acclimated temperature (Fry, 1947;Brett, 1971;Dickson and Kramer, 1971;Beamish, 1978;Houston, 1982;Bernatchez and Dodson, 1985;Johnston and Temple, 2002). Thus, when fish are exposed to temperature changes, they can obtain optimal performance by altering either their behaviour (preference/avoidance) or their physiology (adaptation and acclimation), when the temperature change is sufficiently long. Certain short-term variations in temperature may be unavoidable, however, and this is particularly the case for adult migratory salmon that are returning to their natal streams to spawn. For example, water temperatures in one of the world's greatest salmon-bearing rivers, the Fraser River, BC, Canada, may vary annually on a given date by as much as 6°C. Furthermore, the river temperatures encountered by the Early Stuart stock of Fraser River sockeye salmon Oncorhynchus nerka during its 25-day migration can vary by as much as 10.5°C (Idler and Clemens, 1959) and reach up to 22°C .Given the adult salmon's short migration window and its exposure to a wide variation in temperature, it is possible that acclimation mechanisms that would normally compensate for temperature change may be incomplete. Conversely, Guderley and Blier (1988) suggest that swimming performance and most of its components demonstrate thermal compensation on an evolutionary time scale (i.e. adaptation) such that optimal performance and lowest thermal sensitivity are typically within the temperature range most frequently encountered by the organism. In the case of adult salmon stock, the prediction is that they would retain sufficient physiological flexibility to accommodate the range of temperatures most frequently Our knowledge of the swimming capabilities and metabolic rates of adult salmon, and particularly the influence of temperature on them, is extremely limited, and yet this information is critical to understanding the remarkable upstream migrations that these fish can make. To remedy this situation, we examined the effects of temperature on swimming performance and metabolic rates of 107 adult fish taken from three sto...

We evaluated the effects of past and future trends in temperature and discharge in the Fraser River on the migratory performance of the early Stuart population of sockeye salmon Oncorhynchus nerka. Fish of lower condition exhibited disproportionately higher mortality during the spawning run, elucidating a critical link between energetic condition and a fish's ability to reach the spawning grounds. We simulated spawning migrations by accounting for energetic demands for an average individual in the population from the time of entry into the Fraser River estuary to arrival on the spawning grounds (about 1,200 km upstream) and estimated energy expenditures for the average migrant during 1950-2001. The model output indicates relatively high interannual variability in migration energy use and a marked increase in energy demands in recent years related to unusually high discharges (e.g., 1997) and warmer than average water temperature (e.g., 1998). We examined how global climate change might effect discharge, water temperature, and the energy used by sockeye salmon during their spawning migration. Expected future reductions in peak flows during freshets markedly reduced transit time to the spawning ground, representing a substantial energy [Article] savings that compensated for the effect of the increased metabolic rate resulting from exposure to warmer river temperatures. We suggest that such watershed-scale compensatory mechanisms may be critical to the long-term sustainability of Pacific salmon, given expected changes in climate. However, such compensation will probably only be applicable to some stocks and may be limited under extremely high temperatures where nonenergetic factors such as disease and stress may play a more dominant role in defining mortality. Our results further indicate that a long-term decline in the mean mass of adult sockeye salmon completing their marine residency could erode their migratory fitness during the river migration and hence jeopardize the sustainability of sockeye salmon and the fishery that targets them. 656 RAND ET AL.

We hypothesized that resting and exercise ventilatory chemosensitivity would be augmented in women when estrogen and progesterone levels are highest during the luteal phase of the menstrual cycle. Healthy, young females (n = 10; age = 23 ± 5 yrs) were assessed across one complete cycle: during early follicular (EF), late follicular (LF), early luteal, and mid-luteal (ML) phases. We measured urinary conjugates of estrogen and progesterone daily. To compare values of ventilatory chemosensitivity and day-to-day variability of measures between sexes, males (n = 10; age = 26 ± 7 yrs) were assessed on 5 nonconsecutive days during a 1-mo period. Resting ventilation was measured and hypoxic chemosensitivity assessed using an isocapnic hypoxic ventilatory response (iHVR) test. The hypercapnic ventilatory response was assessed using the Read rebreathing protocol and modified rebreathing tests. Participants completed submaximal cycle exercise in normoxia and hypoxia. We observed a significant effect of menstrual-cycle phase on resting minute ventilation, which was elevated in the ML phase relative to the EF and LF phases. Compared with males, resting end-tidal CO(2) was reduced in females during the EF and ML phases but not in the LF phase. We found that iHVR was unaffected by menstrual-cycle phase and was not different between males and females. The sensitivity to chemical stimuli was unaffected by menstrual-cycle phase, meaning that any hormone-mediated effect is of insufficient magnitude to exceed the inherent variation in these chemosensitivity measures. The ventilatory recruitment threshold for CO(2) was generally lower in women, which is suggestive of a hormonally related lowering of the ventilatory recruitment threshold. We detected no effect of menstrual-cycle phase on submaximal exercise ventilation and found that the ventilatory response to normoxic and hypoxic exercise was quantitatively similar between males and females. This suggests that feed-forward and feed-back influences during exercise over-ride the effects of naturally occurring changes in sex hormones.

Hatchery cutthroat trout Oncorhynchus clarki clarki were used to examine the effects of 48 h and 3 week temperature acclimation periods on critical swimming speed (U crit ). The U crit was determined for fish at acclimation temperatures of 7, 14 and 18 C using two consecutive ramp-U crit tests in mobile Brett-type swim tunnels. An additional group was tested at the stock's ambient rearing temperature of 10 C. The length of the temperature acclimation period had no significant effect on either the first or the second U crit (U crit-1 and U crit-2 , respectively) or on the recovery ratio (the quotient of U crit-2 U crit-1 À1 ). As anticipated, there was a significant positive relationship between U crit-1 and temperature (P < 0Á01) for both acclimation periods, and an increasing, though non-significant, trend between U crit-2 and temperature (P ¼ 0Á10). Acclimation temperature had no significant effect (P ¼ 0Á71) on the recovery ratio. These results indicate that a 48 h acclimation to experimental temperatures within the range of À3 to þ8 C of the acclimation temperature may be sufficient in studies of swimming performance with this species. This ability to acclimate rapidly is probably adaptive for cutthroat trout and other species that occupy thermally variable environments. # 2004 The Fisheries Society of the British Isles

We assessed the prolonged swimming performance (Ucrit), metabolic rate (M-dotO2-min and M-dotO2-max), and oxygen cost of transport (COT) for upper Fraser River pink salmon (Oncorhynchus gorbuscha (Walbaum, 1792); 53.5 ± 0.7 cm FL) and sockeye salmon (Oncorhynchus nerka (Walbaum, 1792); 59.3 ± 0.8 cm FL) across a range of naturally occurring river temperatures using large Brett-type swim tunnel respirometers. Pink salmon were capable of similar relative critical swimming speeds (Ucrit) as sockeye salmon (2.25 FL·s–1), but sockeye salmon swam to a higher absolute Ucrit (125.9 cm·s–1) than pink salmon (116.4 cm·s–1) because of their larger size. Nevertheless, three individual pink salmon (Ucrit-max = 173.6 cm·s–1) swam faster than any sockeye salmon (Ucrit-max = 157.0 cm·s–1), indicating that pink salmon are far better swimmers than has been previously assumed. Metabolic rate increased exponentially with swimming speed in both species and was highest for pink salmon, but swimming efficiency (i.e., COT) did not differ between species at their optimal swimming speeds. The upper and lower limits of metabolism did not differ between species and both M-dotO2-min and M-dotO2-max increased exponentially with temperature, but aerobic costs of transport were independent of temperature in both species. Strong thermal dependence of both swimming performance and COT were expected but not demonstrated in either species. Overall, a higher degree of inter-individual variability in pink salmon swim performance and capacity suggests that this species might not be as locally adapted to particular river migration conditions as are sockeye salmon.