Tidal delta restoration for the recovery of wild Skagit River Chinook salmon: linking estuary restoration to wild Chinook salmon populations

Transcription

1 Tidal delta restoration for the recovery of wild Skagit River Chinook salmon: linking estuary restoration to wild Chinook salmon populations Eric Beamer Skagit River System Cooperative February 2009

2 Acknowledgements Aundrea McBride, Rich Henderson, and Karen Wolf (SRSC) for fieldwork, analysis, and conceptual ideas Kurt Fresh, Casey Rice, and Correigh Greene (NOAA Fisheries) for fieldwork, analysis, and conceptual ideas Kim Larsen (USGS) for Chinook life history research Brian Collins (UW) for historical reconstruction of the delta NW Indian Fisheries Commission, Seattle City Light, ACOE for funding

3 Why do we need estuary restoration for Chinook Salmon? Do Skagit Chinook use the tidal delta? Do Skagit Chinook depend on tidal delta habitat? How has delta habitat changed? Do current habitat conditions in the delta influence the current Chinook population? How are juvenile Chinook migration pathways impacted? Answers leads to importance of tidal delta restoration

4 Skagit: Scale of the Chinook problem in Largest source of wild salmon and freshwater in Puget Sound 6 out of 22 Chinook salmon spawning populations Puget Sound

5 The Skagit Watershed, its historic delta, and the spawning ranges of 6 wild Chinook salmon populations

6 Relative juvenile abundance 50% 40% 30% 20% 10% Wild Skagit Chinook Salmon Ocean-type Chinook are present in the delta for 6-8 months each year Lower River Tidal Delta Bay Nearshore Bay Offshore 0% J F M A M J J A S O N D Month

7 Do Skagit Chinook depend on the delta? Known Skagit River Chinook salmon life history types: Fry migrants Tidal delta rearing migrants Parr migrants Yearling migrants

8 All 6 Chinook populations have delta rearing fish 100% N=33 N=33 N=14 N=16 80% 60% 40% 20% Upper Sauk Suiattle Cascade River Upper Skagit Low er Skagit Low er Sauk 0% fry migrants delta users parr migrants yearlings

9 Delta Habitat

10 Skagit Estuary Habitat Change Skagit tidal delta habitats smaller and more fragmented. Rearing opportunity of tidal delta rearing Chinook reduced 88% Restoration opportunities exist at historic delta sites.

11 How are Skagit Chinook influenced by current habitat conditions?

12 Season Average Fork Length of fish in blind channel habitat (mm) Season Average Fish/ha of blind channel Density dependence in the tidal delta 16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000 0 A - Wild Subyearling Chinook in Skagit Delta R 2 = 0.76 p = ,000,000 4,000,000 6,000,000 8,000,000 Freshwater Outmigration Population B - Wild Subyearling Chinook in Skagit Delta R 2 = 0.82 p = ,000,000 4,000,000 6,000,000 8,000,000 Freshw ater Outm igration Population Freshwater outmigrant population estimates from Seiler et al. 2002

13 % Fry migrant in Skagit Bay catch Nearshore density dependent movement response observed downstream C - Wild Subyearling Chinook in Skagit Bay Nearshore 50% 40% 30% 20% 10% 0% R 2 = 0.91 p = ,000,000 4,000,000 6,000,000 8,000,000 Freshwater Outmigration Population Where do they go downstream? Non-natal pocket estuaries early in the year increased growth refuge from predators

14 Habitat Connectivity (how easily can fish find available habitat?) Local and landscape scales Function of distance traveled and complexity of pathway delta channel branching in tidal habitats - depth

15 Ln Juvenile Chinook/ha Local scale connectivity matters Varies by Site Varies by Tide High Tide Level Relationship between Fish Use and Access Opportunity Depth y = x R 2 = Depth of water (ft) at channel entrance at High Tide before sampling

16 Wild subyearling Chinook density (fish/ha) Landscape connectivity matters Skagit estuary sites in ,000 12,000 10,000 8,000 6,000 4,000 2,000 R 2 = R 2 = Connectivity Index

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18 Potential Tidal Delta Restoration Fisher Slough

19 Project design matters Site specific constraints Project objectives/goals fit into a larger picture (e.g., Chinook recovery) Example: Tide gates v. dike removal what are the juvenile Chinook salmon results?

20 Juvenile Chinook density (fish/ha) Wild juvenile Chinook salmon per hectare Wild juvenile Chinook salmon per hectare Wild juvenile Chinook salmon per hectare Wild juvenile Chinook salmon per hectare Wild juvenile Chinook salmon per hectare Wild juvenile Chinook salmon per hectare Deepwater Slough (Dike Removal) Blind Channel A - Blind Channel Habitat, 2001 Distributary Channel D - Distributary Channel Habitat, ,000 35,000 30,000 30,000 25,000 20,000 15,000 Reference Treatment 25,000 20,000 15,000 Reference Treatment ,000 10,000 5,000 5,000 0 March April May June July 0 Mar Apr May Jun Jul B - Blind Channel Habitat, 2002 E - Distributary Channel Habitat, ,000 35,000 30,000 30,000 25,000 20,000 15,000 Reference Treatment 25,000 20,000 15,000 Reference Treatment ,000 10,000 5,000 5,000 0 March April May June July 0 Mar Apr May Jun Jul C - Blind Channel Habitat, 2003 F - Distributary Channel Habitat, ,000 35,000 30,000 30,000 25,000 20,000 15,000 Reference Treatment 25,000 20,000 15,000 Reference Treatment ,000 10,000 5,000 5,000 0 March April May June July 0 Mar Apr May Jun

21 Average fish per set Juvenile Chinook per set Average fish per set Average fish per set Juvenile Chinook salmon, Upstream TG Downstream TG Fornsby Self Regulating Month Tidegate (opened in 2006) Juvenile Chinook salmon, Upstream TG Downstream TG Month Juvenile Chinook salmon, Upstream TG Downstream TG Month SRT

22 How effective is delta restoration for ESA Chinook Recovery? It s not just about acres restored It s about achieving Chinook population recovery goals Successes and failures of restoration need to be integrated with other H s

23 Photo by Todd Bennett The End