Tony Farrell Zoology Department & Faculty of Land and Food Systems University of British Columbia, Canada Adult salmon in hot water Outline 1. Fraser River adult sockeye salmon migrations & temperature changes 2. Aerobic metabolic scope - a predictive tool for temperature effects? 3. Broader applications in aquatic ecosystems?

Sockeye salmon: post-glaciation invaders British Columbia Vancouver Fraser River Watershed Pacific Ocean CANADA 130 Fraser River sockeye salmon populations Return every 4 years in mid/late summer ~30-day to migrate upriver & spawn

QCI POST detection array JS Fraser River JDFS Acoustic biotelemetry of migration behaviour: individuals vary in marine migration route & speed ? A caveat when predicting population behaviours

Fish temperature increases abruptly on river entry Avoidance behaviours provide only temporary temperature relief Fraser R. gradually cools after the August peak temperature Lower Fraser River Shuswap Lake Data from an I-button temperature logger for an individual sockeye approaching the Fraser R. & during its ~30 day upstream migration

Source: Pacific Salmon Commission min average max Date River temperature, o C Based on historical data (60 years to 2003) from temperature loggers in lower mainstem Fraser River near Mission 2004 Fraser River temperature during sockeye upriver migration

Salmon are facing increasingly warmer temperatures as the spawning dates of sockeye are unchanged (genetically determined) Massive in-river sockeye mortality in particularly hot summers, e.g Hypothesis: High water temperature  en-route deaths Peak river temperature has increased ~1.8 o C during past 55 years Climate change for the lower Fraser River Temp, o C

Percentage of fish encountering a river temperature (up to 2003) Derived by combining historical river temperature data & migration data (~60/10 years) What river temperatures have been experienced? Depends on salmon population & timing of river entry

Summary so far … 1.Sockeye have been in the Fraser R. for last 10,000 years, exploiting the habitat revealed by retreating glaciers. 2.Sockeye spend 2 years growing in cool Pacific Ocean, but must migrate up the warmer Fraser R. in the summer to spawn once. 3.Peak summer Fraser R. temperatures have increased ~2 o C over the past ~50 years & now exceed 20 o C. 4.Recent river temperature exposures during migration can be estimated for salmon populations from historical data.

Temperature ( o C) Resting MR Q 10 -driven increase in resting MR Maximum MR Q 10 -driven increase in maximum MR up until T opt T opt Why is temperature so important for salmon? = aerobic scope, the energy available for activity Temperature controls metabolic rate Metabolic rate

Temperature ( o C) T opt Temperature determines aerobic scope T crit Metabolic rate T crit = no aerobic scope T crit Temperature ( o C) T opt Aerobic scope T opt = max aerobic scope

How is aerobic scope measured in adult salmon? Aerobic scope = (maximum Mo 2 while swimming - routine Mo 2 ) Perform experiments at different water temperatures T opt Aerobic Scope T crit Temp. Mobile swim tunnel respirometry Measure a fish’s oxygen consumption (Mo 2 )

Aerobic scope vs. temperature profiles for three Fraser R. salmon populations Solid line = interpolated from field data (N>30) Broken line = extrapolation to T crit (Lee et al. 2003) Gates sockeye Chehalis coho Weaver sockeye T opt Gates Creek Sockeye T opt = 16.3 o C Scope = 10.7 mg O 2 kg -1 min -1 T crit = 24.4 o C Weaver Creek Sockeye T opt = 14.3 o C Scope = 7.9 mg O 2 kg -1 min -1 T crit = 20.4 o C Chehalis River Coho T opt = 8.1 o C Scope = 7.5 mg O 2 kg -1 min -1 T crit = 17.0 o C

Temperature (°C) Temperature frequency distribution 0% 4% 8% 12% 16% Aerobic scope (mg O 2 kg -1 min -1 ) Gates Creek Sockeye Temperature (°C) % 4% 8% 12% 16% Chehalis Coho Aerobic scope (mg O 2 kg -1 min -1 ) Temperature frequency distribution Key points Populations vary in their: - absolute aerobic scope, - T opt (= max scope) - T crit (= no scope) As little as 6 o C between T opt and T crit Population variability appears to match their experiences Lee et al Temperature (°C) % 4% 8% 12% 16% Weaver Creek Sockeye Aerobic scope (mg O 2 kg -1 min -1 ) Temperature frequency distribution Hell’s Gate

Does an abnormally warm year matter for salmon migration? 2004 = Red temperature data Farrell et al. 2008

Survival to spawning area of 2004 Weaver sockeye Biotelemetry on 5 different dates during seasonal river cooling T crit =20.4 o C T opt = 14.3 o C Todd Mathes M.Sc. thesis N = # of individual fish

Summary so far … 1.Sockeye metabolism & aerobic scope are temperature-dependent. 2.Aerobic scope is the energy available above routine needs & has a T opt & T crit. 3.Peak summer river temperatures have exceeded T crit for some sockeye salmon populations & these periods are associated with “missing salmon”. 4.T opt & T crit are likely to be stock-dependent. Thus, predictions using aerobic scope data should be done at the population level.

Heart can no longer pump enough blood = Resting fish = Swimming fish (70% U crit ) Temperature (ºC) Recovery a bf c d de e f a bf cg de e fg * * * * * * 15 Heart rate (beats min -1 ) Steinhausen et al Acute  T o C: sockeye resting or swimming at a constant ~70% U crit Why don’t sockeye salmon like it hot?

Cardiac arrhythmias develop at high temperature Cardiac output (ml min -1 kg -1 ) Clark et al Acute  T o C: resting chinook salmon

Can aerobic scope provide a broader conceptual framework for predicting climate change impacts in aquatic ecosystems? Pros: - Metabolism of most aquatic vertebrates, all invertebrates & all phytoplankton is governed by temperature - Metabolic rate is key to growth & survival behaviours - Growth and population measure reflect aerobic performance Cons: - Necessary data base is largely lacking - Examples limited to Pacific salmon (our work), Atlantic cod, & ocean pout (Hans P ö rtner et al.) Possibly salmon sharks & tuna (Barbara Block et al.) Pörtner and Farrell (2008)

Conceptual framework beyond aerobic scope- growth & abundance?

Conceptual framework for species interactions? Under the warming scenario the “reds” could: - Dominate over the “blues” - Be resource-limited by the “blues”

Temperature ( o C) Aerobic thermal window Eggs, early larvae Juveniles Growing adults Spawners Some life stages will be the most temperature-sensitive A series of aerobic scope curves during growth Scope for performance Sequence of life stages

Conclusions Tim Clark (UBC); Karl English (LGL); David Welch (Kintama) Aerobic scope holds promise for predicting the effects of temperature change on Pacific salmon populations. Potential exists for a broader conceptual application to aquatic ecosystems, but more data are needed. Scott Hinch, UBC David Patterson, DFO MariaLinda Erika