Mike Chotkowski, Ph.D. Field Supervisor USFWS Bay Delta Fish and Wildlife Office. *With a few comments on longfin smelt

Transcription

1 Mike Chotkowski, Ph.D. Field Supervisor USFWS Bay Delta Fish and Wildlife Office *With a few comments on longfin smelt

2 Evolution: freshwater derivative of surf smelt Life span: annual Life history: opportunistic, estuarine dependent Adult size: ~ 3 inches

3 Abundance index Decline noted in early 1980s Listed as threatened in 1993 Abruptly declined again after 1999 Series of new record low indices Significant rebound in 2011 Fall Midwater Trawl Year

4 TOP-DOWN Prior Fish Abundance Water Diversions FISH ABUNDANCE Food availability Predation Food quality PHYSICAL & CHEMICAL FISH HABITAT Temperature Turbidity Salinity Contaminants Disease Toxic algae BOTTOM-UP

5 D E L T A Summer Clams and Limnoithona Reduced Food in LSZ Increased Predation Loss (?) Fall Reduced Outflow Reduced Habitat Area Reduced Size & Egg Supply S M E L T Improved Survival Late Growth Start High Entrainment of Adults and Early Larvae Decreased Number Survive to 2 Years Old Spring VAMP Winter Jan-Mar Exports

6 Litigation by DWR and water users RPA Implementation success Litigation effects on collaborative science

7 Needed to avoid jeopardy or adverse modification of delta smelt critical habitat Elements OMR flow Fall Delta outflow Tidal marsh habitat

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10 Delta smelt risk entrainment while migrating, spawning, or rearing in the southern half of the Delta The fish use hydrodynamic and other habitat cues to decide whether to move or stay OMR is the best indicator of age-0 smelt entrainment The Projects affect OMR and thus contribute to entrainment risk Most entrainment is not detected

11 Objective: Protection from entrainment Timing: December through June Potential actions: to OMR Technical issues: distribution, turbidity, flow

12 Number of Smelt Working Group meetings BiOp default (-5000 cfs), VAMP, or NMFS BiOp 30 FWS action taken

13 Fall X2 issue is analogous to base flow issues for salmonid streams Fall X2 issue is about habitat, not entrainment Fish catch indicates habitat suitability [?] Distribution correlated with water quality Water quality changes have restricted smelt spatial distribution Restricted distribution limits viability Projects influence water quality via Delta outflow

14 Habitat index Mean September-December X2 (km)

15 During September and October set X2 position at an average of 74 km following wet years 81 km following above normal years During November pass inflow through reservoirs to augment outflow up to the target Use adaptive management to review and modify

16 Abundance index Fall Midwater Trawl Year

17 ESA listing warranted but precluded (2012)

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19 Delta smelt growth rate is food-limited and habitatlimited Longfin smelt population growth rate is food-limited and flow-limited The two biggest contributors to food limitation: Overbite clam (Potamocorbula amurensis) Eats prey that larval smelt eat Suppresses supporting open-water food web Limits scope for growth Water temperature Forces longfin smelt seaward Limits scope for growth

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21 Source: Cloern and Jassby (in press)

22 Knocked out diatom standing stock in the late spring-summer (Alpine and Cloern 1992; Jassby et al. 2002) Smaller diatom standing stock less able to metabolize NH x load (expectation based on biochemistry) Reductions in some zooplankton spp and changes in spp composition (facilitated introductions) (Kimmerer and Orsi 1996; Winder and Jassby 2011) Lower fish carrying capacities (Kimmerer et al. 2000; Kimmerer 2002) Slower delta smelt growth rates (Sweetnam 1999; Bennett 2005)

23 Source: Dettinger (2005)

24 Current growth rates are lower than years ago Delta smelt will need more food in the future just to maintain current growth rates Fish lose competitive abilities at lower water temperatures than temps that will kill them (Taniguchi et al. 1998; Marine and Cech 2004)

25 Managing water project effects on delta smelt Addressing Food web issues and climate change