Wetland Recovery and Salmon Population Resilience: A Case Study in Estuary Ecosystem Restoration Daniel L. Bottom NOAA NW Fisheries Science Center, Newport, OR Kim K. Jones, Trevan J. Cornwell, Staci Stein Oregon Department of Fish and Wildlife, Corvallis, OR Lance A. Campbell Washington Department of Fish and Wildlife, Olympia, WA Photo: Carey Smith, Pacific Coast Joint Venture, Vancouver, WA
Life history diversity in Chinook salmon Fry migrants Subyearling migrants Yearling migrants Subyearling migrants (mid summer) Subyearling migrants (late summer/fall) From Reimers 1973
Conventional life history of Coho salmon Stream rearing (~1 ½ years) Ocean rearing (~1 ½ years)
Resilience of Salmon with Diverse Life Histories High Diversity Environmental variability Reduced Diversity Salmonid Response
Objective Determine whether recovery of tidal wetlands in Salmon River estuary has benefited Chinook and coho salmon, as indicated by: Juvenile habitat use and performance within the estuary (residency, foraging success, growth) Population response within the basin (life history diversity, production, resilience) Salmon River Research Chinook salmon study (1998 2005) Coho salmon study (2008 2011) Pre-hatchery survey (1975-77) Photo: Carey Smith, Pacific Coast Joint Venture, Vancouver, WA
Salmon River Basin 195 km 2 watershed Estuary area 800 ha Head of tide ~ Rkm 6.5 Fish hatchery at Rkm 8 Estuary protection: Cascade Head Scenic Research Area (1974)
Salmon River Estuary Marsh Restoration >175 ha restored 1978 1987 Reference 1996 2011
Life-cycle perspective: Juvenile abundance in streams (coho) Migration from watershed Estuary habitat use, movement, timing and CPUE, growth Adult returns (spawner surveys) Life history reconstruction: juv, adult otoliths PIT tags (coho) Survival (coho)
Life History Variation in Juvenile Salmon Sampling at estuary mouth to collect oceanbound juveniles Reconstruct life histories of juveniles and adults from otolith chemistry Strontium indicator of salt-water entry Back-calculated size at estuary entry based on otolith:fish size relationship Growth rates from daily increments
Chinook life history diversity has expanded with increased estuary rearing opportunity 100 80 60 Lower estuary Mid estuary Upper estuary 2000 100 80 60 Lower estuary Mid estuary Upper estuary 75' seine (1977) Upper estuary 125' seine (1977) 1975 40 40 20 20 CPUE (number/seine haul) 0 100 80 60 40 20 0 100 80 2001 2002 CPUE (number/seine haul) 0 100 80 60 40 20 0 100 80 1976 1977 60 60 40 40 20 20 0 0 Mar May Jul Sep Nov Mar May Jul Sep Nov
Life histories of outmigrating juvenile Chinook Summer Fall Early Fry Spring Summer E Fry ER<30d E Fry ER>30d Spring Migrant ER<30d Spring Migrant ER> 30d Summer Migrant ER<30d Summer Migrant ER>30d Fall Migrant ER< 30d Fall Migrant ER> 30d (adapted from Volk et al. 2010) Size at Estuary Entry (mm) Emergent Fry < 45 Spring (MAM) 47 64 Summer (JJA) 55 96 Fall (SON) 97 109
Juvenile Life Histories of Returning Adult Chinook All 4 migrant types contributed to surviving adults 25 40% of spawners were spring fry migrants that were rare or absent when the marshes were diked Run Year 2004 (n=145) Run Year 2005 (n=85) Size at Estuary Entry (mm FL) (L. Campbell unpubl. data)
Coho Population Studies Salmon River 2008-2011 Jones et al. 2014 PIT Array, Smolt Trap
Juvenile coho use of upper estuary and wetlands Yearlings in upper estuary in the spring 27% of tagged yearlings used 96 Marsh (2010) Contrary to the conventional coho life history, subyearlings reared in estuary wetlands Fry entered in spring; parr were present late fall and winter CPUE upper Salmon R. estuary yearling subyearling
Diverse juvenile coho life histories in Salmon River (Jones et al. 2014) Rearing Environment Stream and Tidal Fresh Estuary Ocean Yearling Fry Nomad Parr Juvenile Migrant Type
Juvenile Life Histories of Returning Adult Coho (Jones et al. 2014) Estuary rearing types Yearling Fry Nomad Parr 20-35% of returning adults had reared in the estuary Estuary life histories were absent when marshes were diked Estuary restoration has increased coho life history diversity as well as production
Coho life history diversity has expanded with increased estuary rearing opportunity (Jones et al. 2014)
Lessons from Salmon River Restoring estuary habitat has enhanced life history expression in both Chinook and coho salmon Coho that leave natal streams as subyearlings are not lost to the population but use the estuary Estuary life histories linked to restored wetlands contributed 25-40% of adult Chinook and 20-35% of adult Coho produced in Salmon River Life history diversity (and the habitat opportunities that support it) is fundamental to the productivity as well as the resilience of salmon populations
Case Studies in Salmon Resilience