Changes in Production of one and two year old Steelhead Trout Smolts during Drought Conditions in a Northern California Stream Michael D. Sparkman (CDFW) Fisheries Biologist / Environmental Scientist Phillip Bairrington (CDFW)

Acknowledgements Funding provided by: Funding provided by: CDFW AFRAMP CDFW AFRAMP CDFW SRRCP CDFW SRRCP FRGP FRGP SFRA SFRA My field crews (too many to list) My field crews (too many to list)

Introduction Long term studies are needed to address biological and environmental variability. Long term studies are needed to address biological and environmental variability. Recent drought in CA, beginning 2012 to at least Recent drought in CA, beginning 2012 to at least Drought in 2014 was the worst in the past 1,200 years. Drought in 2014 was the worst in the past 1,200 years. Griffin D, and KJ Anchukaitis How unusual is the California drought? Geophysical Research Letters, 41,

Focus 1+ Steelhead smolt abundance in Steelhead smolt abundance in 2015 Age-0 in 2014 Age-0 in 2014 Emigrated as age-1 in 2015 Emigrated as age-1 in Steelhead smolt abundance in Steelhead smolt abundance in 2015 Age-0 in 2013 Age-0 in 2013 Age-1 in 2014 Age-1 in 2014 Emigrated as age-2 in 2015 Emigrated as age-2 in 2015

Why more smolts in 2015? Brood year (cohort) relationships Brood year (cohort) relationships Environmental variables during summer months Environmental variables during summer months Stream Flow (cfs) Stream Flow (cfs) Stream Temperature (C) Stream Temperature (C)

Redwood Creek (RC) 7 th order stream 7 th order stream Sediment and Temperature Impaired Sediment and Temperature Impaired Intensively monitored watershed Intensively monitored watershed Supports runs of Steelhead Trout*, Chinook Salmon*, Coho Salmon*, Cutthroat Trout, Pink Salmon Supports runs of Steelhead Trout*, Chinook Salmon*, Coho Salmon*, Cutthroat Trout, Pink Salmon

RC Watershed

Methods Modified rotary screw traps to capture juvenile Steelhead Trout. Modified rotary screw traps to capture juvenile Steelhead Trout. 24 hrs/d, 7 d/wk 24 hrs/d, 7 d/wk Mark/recapture to determine population abundances. Mark/recapture to determine population abundances. 3 – 4 efficiency trials per week 3 – 4 efficiency trials per week Carlson et al. population model Carlson et al. population model Tested in field for accuracy with counting fence Tested in field for accuracy with counting fence

Modified RST

Lower RC RST

End of Season

Juvenile SH Age Classes

0+ Chinook Salmon Catch (1 d)

1+ SH Smolt

2 + SH Smolt

Percent > in 2015

Summer Conditions in 2013 Stream flows (cfs) in June-August 2013 Stream flows (cfs) in June-August 2013 Upper RC: Avg = 11 cfs or 69% < Average ( ) Upper RC: Avg = 11 cfs or 69% < Average ( ) Lower RC: Avg = 54 cfs or 64% < Average ( ) Lower RC: Avg = 54 cfs or 64% < Average ( ) Stream temperature (C) in June-July 2013 Stream temperature (C) in June-July 2013 Upper RC: Avg. = 19.1 C, or 6.6% > Avg ( ) Upper RC: Avg. = 19.1 C, or 6.6% > Avg ( ) Lower RC: Avg. = 17.2 C, or 3.3% > Avg ( ) Lower RC: Avg. = 17.2 C, or 3.3% > Avg ( )

Summer Conditions in 2014 Stream flows (cfs) in June-August 2014 Stream flows (cfs) in June-August 2014 Upper RC: Avg = 11 cfs or 67% < Average ( ) Upper RC: Avg = 11 cfs or 67% < Average ( ) Lower RC: Avg = 54 cfs or 61% < Average ( ) Lower RC: Avg = 54 cfs or 61% < Average ( ) Stream temperature (C) in June-July 2014 Stream temperature (C) in June-July 2014 Upper RC: Avg. = 19.1 C, or 6.1% > Avg ( ) Upper RC: Avg. = 19.1 C, or 6.1% > Avg ( ) Lower RC: Avg. = 18.0 C, or 5.8% > Avg ( ) Lower RC: Avg. = 18.0 C, or 5.8% > Avg ( )

Environmental Conditions June – Aug. stream flows were similar in 2013 and 2014 for both locations, and 61 – 69% lower than previous year’s average. June – Aug. stream flows were similar in 2013 and 2014 for both locations, and 61 – 69% lower than previous year’s average. June / July Stream Temperatures were similar in 2013 and 2014 for both locations, and 3 – 6% higher than the previous year’s average. June / July Stream Temperatures were similar in 2013 and 2014 for both locations, and 3 – 6% higher than the previous year’s average.

1 + Steelhead Trout

Brood Year Relationships

Additional Evidence? 0 + SH catch in 2014 was 1.5 times greater than average of 2003 – SH catch in 2014 was 1.5 times greater than average of 2003 – SH abundance in 2015 was 1.6 times greater than average of 2003 – SH abundance in 2015 was 1.6 times greater than average of 2003 – Nearly same increase for Brood Year when age- 0 and age-1 Nearly same increase for Brood Year when age- 0 and age-1

Summer CFS on 1 + SH Abundance

Abiotic Variables and 1 + SH No relationship between summer low flows that age-0 fish experienced before migrating as age-1 smolts the next year (p > 0.05). No relationship between summer low flows that age-0 fish experienced before migrating as age-1 smolts the next year (p > 0.05). Applies to winter flows as well (p > 0.05). Applies to winter flows as well (p > 0.05). No relationship between summer stream temperatures that age-0 fish experienced before migrating as age-1 smolts the next year (p > 0.05). No relationship between summer stream temperatures that age-0 fish experienced before migrating as age-1 smolts the next year (p > 0.05).

2 + Steelhead Trout

0 + SH (x) on 2 + SH (x+2)

1 + SH (x) on 2 + SH (x+1)

Up. RC 1 + SH (x) on Up. RC 2 + SH (x+1)

Upper RC 2 + SH on Lower RC 2 + SH

1 + SH and 2 + SH (same year)

Summer cfs on 2 + SH

Abiotic Variables on 2 + SH No relationship between stream flows that 0+ or 1 + SH experienced before out-migrating as 2 + SH (p > 0.05 for each test). No relationship between stream flows that 0+ or 1 + SH experienced before out-migrating as 2 + SH (p > 0.05 for each test). No relationship between stream temperatures that 0 + or 1 + SH experienced before out- migrating as 2 + SH (p > 0.05 for each test). No relationship between stream temperatures that 0 + or 1 + SH experienced before out- migrating as 2 + SH (p > 0.05 for each test).

Conclusions 1 + SH increase in abundance in 2015 most likely due to brood year strength in SH increase in abundance in 2015 most likely due to brood year strength in No relationships with summer low flows and summer stream temperatures at either location in basin. No relationships with summer low flows and summer stream temperatures at either location in basin.

Conclusions (2 + SH) 2 + SH abundances in lower RC were not related to 0 + SH or 1 + SH in previous years. 2 + SH abundances in lower RC were not related to 0 + SH or 1 + SH in previous years. No Brood Year influences were detected. No Brood Year influences were detected. 2 + SH abundances in upper basin were positively related to 1 + SH in upper basin in previous years. 2 + SH abundances in upper basin were positively related to 1 + SH in upper basin in previous years. Brood Year influence for upper basin populations. Brood Year influence for upper basin populations.

2 + Steelhead Trout 2 + SH abundances in lower RC were positively correlated with 2 + SH abundances in the upper basin in a given year. 2 + SH abundances in lower RC were positively correlated with 2 + SH abundances in the upper basin in a given year. When 2 + SH in upper basin do well, so do the 2 + SH passing through the lower basin. When 2 + SH in upper basin do well, so do the 2 + SH passing through the lower basin.

2 + SH continued 2 + SH abundances in lower basin were positively correlated with 1+ SH abundances in the same years. 2 + SH abundances in lower basin were positively correlated with 1+ SH abundances in the same years. When 1 + SH do well in a given year, so do the 2 + SH. When 1 + SH do well in a given year, so do the 2 + SH.

Why more 2 + SH in 2015? Relatively strong Brood Year for 1 + SH (upper RC) in 2014 lead to more 2 + SH in upper basin in Relatively strong Brood Year for 1 + SH (upper RC) in 2014 lead to more 2 + SH in upper basin in When we have more 2 + SH in the upper basin, we have more 2 + SH in the lower basin. When we have more 2 + SH in the upper basin, we have more 2 + SH in the lower basin.

Environmental Conditions and 2 + SH abundance in lower RC in 2015 “Best Guess”: Since cfs in 2014 was 60 + % less than previous years, there was less space for prey items when 2 + SH were yearlings. “Best Guess”: Since cfs in 2014 was 60 + % less than previous years, there was less space for prey items when 2 + SH were yearlings. We speculate that 2 + SH (when a 1 + SH) had an easier time feeding upon 0 + SH, 0 + Chinook, and aquatic invertebrates due to less space. We speculate that 2 + SH (when a 1 + SH) had an easier time feeding upon 0 + SH, 0 + Chinook, and aquatic invertebrates due to less space. Avg. FL (mm) in 2015 was the highest of record, and 14 mm > average ( ). Avg. FL (mm) in 2015 was the highest of record, and 14 mm > average ( ).

Conclusions Steelhead Trout are a resilient fish, and we observed that the recent drought conditions in RC did not overly impact survival to smolting in Steelhead Trout are a resilient fish, and we observed that the recent drought conditions in RC did not overly impact survival to smolting in However, drought conditions in RC were not as severe as streams in other parts of the state. However, drought conditions in RC were not as severe as streams in other parts of the state.

Conclusions Long term data sets at multiple locations within the RC watershed were required to answer specific questions regarding increases in Steelhead Trout smolt abundances we observed Long term data sets at multiple locations within the RC watershed were required to answer specific questions regarding increases in Steelhead Trout smolt abundances we observed 2015.

Concerns Long term studies are increasingly becoming harder to fund. Long term studies are increasingly becoming harder to fund. All studies in RC will not be funded in 2017 and in the foreseeable future. All studies in RC will not be funded in 2017 and in the foreseeable future. Steelhead Trout smolts (age-2) are difficult to capture/recapture, and the by-product in RC is capturing large numbers of 0+ Chinook and 0+ Steelhead Trout. Steelhead Trout smolts (age-2) are difficult to capture/recapture, and the by-product in RC is capturing large numbers of 0+ Chinook and 0+ Steelhead Trout. Recent 4d Rule Take limitations (capture/handle/release) on Chinook Salmon may make it impossible to get good estimates for 2 + SH smolts. Recent 4d Rule Take limitations (capture/handle/release) on Chinook Salmon may make it impossible to get good estimates for 2 + SH smolts.

Thank You