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. Small watershed (75km 2 ) 23km of stream accessible to anadromous fish “native” resident fish above barriers Small hatchery Dynamic flow regime (28m 3 s -1 to 0.1m 3 s -1 ) Small Estuary (closes seasonally) Scott Creek Map: Rob Schick, NMFS

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

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

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

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

7. Genotype distribution in upper watershed 0.00 0.10 0.20 0.30 0.40 507090 110 130 150 170 190 210 230250 270 Fork length Frequency Resident (n=128) Anadromous (n=209)

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 0.00 2.00 4.00 6.00 8.00 024681012 Month ATPase Resident Anadromous Na + K + -ATPase Physiology 0 2 4 6 0246810121416 ATPase Frequency Resident Anadromous

11. Why do wild fish migrate at such small sizes? 0 0.04 0.08 0.12 0.16 507090 110130150170190210230250 Fork Length (mm) Frequency Typical steelhead smolt size distribution

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

13. Is the estuary a nursery? Ocean upper watershedestuary/lagoon 85% of returning adults use estuary pathway Size threshold for ocean survival

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

15. Size of recaps at smolt trap in spring 0 2 4 6 8 10 12 14 16 18 20 6080100120140160180200220240260280300 Fork Length Frequency Upstream Estuary (previous summer) X

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

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. Estuary Environmental Conditions “Lethal” levels

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

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

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

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

25. Density-dependent Estuary Growth in Steelhead

26. 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?

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

28. Escapement  Early 20th century spawning population was 4-10 times larger

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

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

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

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