Temperature effects on swimming performance, energetics, and aerobic capacities of mature adult pink salmon (Oncorhynchus gorbuscha) compared with those of sockeye salmon (Oncorhynchus nerka)

Abstract

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.

Exceptional aerobic scope and cardiovascular performance of pink salmon (Oncorhynchus gorbuscha) may underlie resilience in a warming climate

“…Corroborating previous studies (Williams et al, 1986;MacNutt et al, 2006), the results presented here dispel the historic contention that pink salmon are poor swimmers in comparison with other Pacific salmonids (Heard, 1991). Thus, Harrison River pink salmon should possess the swimming capacity to migrate to more distant freshwater spawning grounds than the Harrison River, including past Hell's Gate, a major hydraulic barrier ~200km upriver of the Fraser River mouth (Hinch and Bratty, 2000).…”

Aerobic scope increases throughout an ecologically relevant temperature range in coho salmon

“…Selong et al, 2001;Martins et al, 2011;Jeffries et al, 2012a,b;Vornanen et al, 2014). Across taxa, we need to understand why limitations to oxygen transport capacity (specifically AS) appear to align with temperature-specific fitness outcomes in some studies (Pörtner and Knust, 2007;Eliason et al, 2011;Martins et al, 2011;Khan et al, 2014;Chen et al, 2015) but not in others (MacNutt et al, 2006;Clark et al, 2011;Overgaard et al, 2012;Ern et al, 2014;Gräns et al, 2014;Norin et al, 2014). Improving our understanding of how AS changes across life stages (e.g.…”

“…Fangue et al, 2006;Healy and Schulte, 2012;Ferreira et al, 2014). Furthermore, some populations of Fraser River salmon clearly appear to either maintain or even increase AS at temperatures well beyond the mode for the historically experienced river temperatures during their adult river migration (MacNutt et al, 2006;Clark et al, 2011;Eliason et al, 2013). Indeed, AS in some fish species exhibits a steady increase until near-lethal temperatures are reached (e.g.…”

Potential effects of global climate change on National Fish Hatchery operations in the Pacific Northwest, USA

“…Across the terminal portion of the migration, fish face thermal stress in the freshwater environment that can lead to delays in migration and/or premature mortality and migration failure (Salinger & Anderson 2006). During aerobic swimming that is required for migration, aerobic scope for activity (the difference between basal and maximum metabolic rates), which constrains sustained and maximum swimming speeds, has been shown to have an optimum temperature in Pacific salmonids (Lee et al 2003, MacNutt et al 2006. Temperatures above this optimum cause inadequate blood flow to tissues resulting in anaerobic respiration and, ultimately, energy depletion, physiological dysfunction, and premature mortality prior to salmon reaching their spawning grounds (Pörtner & Knust 2007, Clark et al 2008.…”

“…Increases in stress hormone concentrations (principally blood cortisol) related to thermal stress lead to decreases in immune function and an increase in infection-and disease-related mortality (Barton & Iwama 1991, Barton 2002. Decreased aerobic scope could directly lead to decreased swimming performance that is vital to surviving predator/prey interactions, navigating complex river flows, and avoidance of any hydropower infrastructure along the migration route (Lee et al 2003, MacNutt et al 2006. The interplay of changing hydrological and thermal patterns in major rivers and the influence of hydropower infrastructure may lead to alteration of behaviorally optimal emigration timing (which also typically coincide with juvenile bypass practices at hydropower facilities) related to high smolt to adult survival (Beckman et al 2000, Scheuerell et al 2009).…”