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Small watershed (75km 2 ) 23km of stream accessible to anadromous fish

Emigration behavior of resident and anadromous juvenile O. mykiss : exploring the interaction among genetics, physiology and habitat Sean Hayes, Chad Hanson, Morgan Bond, Devon Pearse, Andrew Jones, Carlos Garza, Bruce MacFarlane. Scott Creek. Small watershed (75km 2 )

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Small watershed (75km 2 ) 23km of stream accessible to anadromous fish

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  1. Emigration behavior of resident and anadromous juvenile O. mykiss:exploring the interaction among genetics, physiology and habitat Sean Hayes, Chad Hanson, Morgan Bond, Devon Pearse, Andrew Jones, Carlos Garza, Bruce MacFarlane

  2. Scott Creek • Small watershed (75km2) • 23km of stream accessible to anadromous fish • “native” resident fish above barriers • Small hatchery • Dynamic flow regime (28m3 s-1 to 0.1m3 s-1) • Small Estuary (closes seasonally) Map: Rob Schick, NMFS

  3. Upstream resident Mature in estuary (never enter ocean) Ocean upper watershed estuary/lagoon Scott Creek O. mykisslife history strategies

  4. Instream PIT tag readers x x Smolt trap x 3 km Adult weir Seine, hook & line, and electrofishing Scott Creek X= barrier

  5. Resident populations “diverged” >100 yrs ago Do rainbow trout and steelhead differ? Big Creek Above Big Creek, Boyer Scott Creek Above Mill Above 68 63 92 76 Big Creek Adults 60 Scott Creek Adults Weir Adults Hatchery Juveniles Lagoon Juveniles Neighbor-Joining distance tree, with bootstrap values for supported nodes

  6. ? x x x Proportion of fish assigned to Resident or Anadromous ancestry by habitat 100% 90% 80% 70% Anadromous 60% Resident 50% 40% 30% 20% 10% 0% Above Barrier Upstream Smolt trap Estuary

  7. Genotype distribution in upper watershed 0.40 0.30 Resident (n=128) Frequency Anadromous (n=209) 0.20 0.10 0.00 50 70 90 130 190 170 230 250 110 150 210 270 Fork length

  8. Emigration rate from above anadromy barrier • 400 fish PIT tagged above • 2.3 % over the falls • 1.8 % detected at smolt trap

  9. ? Na+ K+-ATPase Physiology

  10. Upstream samples 8.00 Resident 6.00 Anadromous ATPase 4.00 2.00 0.00 0 2 4 6 8 10 12 Month Na+ K+-ATPase Physiology Resident 6 Anadromous Frequency 4 2 0 0 2 4 6 8 10 12 14 16 ATPase

  11. Typical steelhead smolt size distribution Why do wild fish migrate at such small sizes? 0.16 0.12 Frequency 0.08 0.04 0 50 70 90 110 130 150 170 190 210 230 250 Fork Length (mm)

  12. Estuary- Open to Ocean (Jan.-June) Lagoon- Sand Bar Closed (July-Dec.) Does estuary serve as nursery habitat?(Morgan Bond’s thesis)

  13. Black lines indicate upper watershed growth Blue lines indicate migration to estuary and growth 250 200 Size threshold for ocean survival 150 Fork Length (mm) 100 Mean 5th % 95th % 50 YOY 1+ 2+ 3+ 0 Jan Jul Jan Jul Jan Jul Jan Jul Jan 85% of returning adults use estuary pathway Ocean upper watershed estuary/lagoon Is the estuary a nursery?

  14. What happens when water quality degrades? >45% detected moving Upstream each fall (probably >90%) 3 km

  15. X Size of recaps at smolt trap in spring 20 18 16 Upstream Estuary (previous summer) 14 12 Frequency 10 8 6 4 2 0 60 80 100 120 140 160 180 200 220 240 260 280 300 Fork Length

  16. Year 2 Year 3 Year 2 Year 3 A tale of two watersheds No estuary available (in Central California…) Year 1 Functional estuary present Year 1

  17. Acknowledgements • Funding • NMFS • DFG FRGP • NURP • California Sea Grant • Land Owner support • Big Creek Lumber Company • The Wilson Family • Monterey Bay Salmon and Trout Project • Cal Poly Swanton Ranch • Lockheed Martin

  18. Implications of resident trout studies • Should residents be counted in steelhead populations for delisting criteria? • Residents may become steelhead, but this probably happens at low frequencies • Results of resident contribution to anadromous breeding pending

  19. “Lethal” levels Estuary Environmental Conditions

  20. To sea or not to sea? Genotype Frequencies 1 Resident Anadromous 0.8 0.6 Frequency 0.4 0.2 0 Upstream Smolt trap Influence of genotype on migration behavior

  21. After 5-6 months rearing in estuary Steelhead in Scott Creek Typical spring downstream migrant (smolt?) 85% of returning adults use estuary pathway 100mm

  22. Big smolts are less likely to stay Probability of recapture < Fork Length (mm) at Trap

  23. Conclusions Central Coast steelhead adapt for estuarine use Steelhead strategies without estuary • Longer upstream rearing • Fewer smolts, reduced anadromy?

  24. Density-dependent Estuary Growth in Steelhead

  25. Implications for Local Rivers • Larger river- may have more rearing capacity= larger smolts upstream • BUT… is there enough water? • Estuary issues • Breaching • Estuary size reduced? • Enough flow to connect with watershed?

  26. >45% lagoon fish detected moving upstream Lagoon fish move upstream in the fall and then back down in spring

  27. Early 20th century spawning population was 4-10 times larger Escapement ­ ??

  28. Lots of food! Diet consists of Corophium and Eogammarus sp. Why is estuary growth so good?(Jeff Harding’s diet studies)

  29. But where does food come from? • Upper watershed growth poor • Insect diet • Low flow • Low light • low nutrient input into estuary

  30. Hypothesis- Nutrient flow from marine derived nutrients (kelp) enhances productivity (Alison Collins senior thesis) 13C and 15N from Juvenile Steelhead Marine 16 14 12 d15 N (0/00) +/- SD 10 8 Juv. Steelhead - Lagoon Juv. Steelhead - Above Fall 6 Adult Steelhead -26 -24 -22 -20 -18 -16 -14 Coastal Marine Fish d13C (0/00) +/- SD Terrestrial Marine

  31. Why don’t all fish recruit to the estuary?

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