Priority Questions of TID/MID/CCSF Regarding Tuolumne River Salmonids & Macroinvertebrates

1. Priority Questions of TID/MID/CCSF Regarding Tuolumne River Salmonids & Macroinvertebrates

2. Chinook salmon spawning Are population levels constrained by available spawning habitat? Relevance: a) Overall spawning area was reduced by 1997 flood; b) Increased superimposition may result in lower production per female spawner due to mortality of displaced eggs; c) Later emergence timing of superimposed redds may result in later emergence, fry and smolt development resulting in increased mortality risks (e.g., predation, temps, Delta pump direct and indirect losses) during outmigration.

3. Chinook salmon fry/juvenile • Does available physical habitat limit juvenile production? • Relevance: High quality rearing habitat leads directly to higher smolt production

4. Chinook salmon fry/juvenile Do early migrating fry contribute substantially to subsequent escapement? Relevance: Prior seine and RST monitoring suggests flood years with large and early-season fry dispersal are associated with higher subsequent cohort production.

5. Chinook salmon fry/juvenile Does predation of fry/juvenile life-stage within Tuolumne River substantially reduce subsequent cohort production? Relevance: Excessive losses of fry/juvenile life stage will limit subsequent production

6. Chinook salmon smolt outmigration • What level or range of managed flows within existing flow allocations achieves high smolt production at Tuolumne River mouth? • Relevance: Presumptive relationship between smolt production and subsequent escapement.

7. Chinook salmon smolt outmigration In what Tuolumne River locations and under what conditions is predation a significant source of mortality on smolt life stage? Relevance: Presumptive relationship between Tuolumne River smolt production and subsequent escapement. Although presence and absence of predators under several water year types has been documented, few direct predator surveys during smolt outmigration have been conducted to assess impacts.

8. Chinook salmon smolt outmigration How do Delta conditions affect subsequent cohort production from Tuolumne River smolt outmigrants? Relevance: Presumptive relationship between Tuolumne River smolt production and subsequent escapement. Current Delta management (i.e. VAMP) may limit survivable outmigration “window” to smolt outmigration period, which increases relative contribution of smolt vs. fry outmigrants.

9. Oncorhynchus mykiss (rainbow trout/steelhead) Fry/Juvenile What is the distribution of suitable juvenile habitat during summer conditions? Relevance: Bioenergetic and survival limitations may constrain carrying capacity of suitable cool water habitat.

10. Oncorhynchus mykiss (rainbow trout/steelhead) Fry/Juvenile What is the relative abundance of juvenile O. mykiss by habitat type? Relevance: Bioenergetic and survival limitations may constrain carrying capacity of suitable cool water habitat. Limited knowledge of habitat use relative to existing and restored habitats.

11. Benthic Macroinvertebrate Community • Does relative abundance and diversity of Tuolumne River invertebrates indicate suitable conditions of instream productivity? • Relevance: Provides independent measure of ecosystem health and indicator of fish food resource.