The influence of variable marine survival on fishery management objectives for wild steelhead Dan Rawding & Charlie Cochran

Population Monitoring Program Adult and smolt population estimated using mark-recapture or mark-resight Trout Creek adult census or trap count except 1995,96,& 97 -timing & redd surveys Precision of mark-recapture population estimates (95%CI) > + 20% Wild Spawner equivalents –Reproductive success of hatchery steelhead to the smolt stage ~ 30% (Kostow 2003) –Reproductive success of hatchery steelhead to the adult stage ~ 12% (Leider et al & Hulett et al. 1996)

Wind River Steelhead Biological Information ~95% summer and ~5% winter steelhead Segregation of race is due to Shipherd Falls –4 falls/cascades from 2 to 4 meters Summer steelhead sex ratio ~2:1 (F:M) Repeat spawner rate ~ 6% Repeats both spawners & recruits Spawner-Recruit modeling assumes steelhead are semelparous –therefore Smolt to Adult Survival (SAS) includes repeats

Out of Subbasin Information Unaccounted for loss between BON and Shipherd Falls is ~17% and assumed to be harvest from Zone 6 and sport fishing Mortality not accounted for –BON Adults 1.4% & Smolts 13.4% –Caspian Terns (Rice & Sand Islands)~10% –Cormorants ~2% –Marine Mammals Predation (2%) –Mainstem fishing below BON (2%?) –Northern Pikeminnow predation ?

Terms Spawner-Recuit (SR) or Spawner-Recuit-Relationship (SRR) SRR –Assume lognormal errors –Beverton-Holt (BH) –Ricker (R) –Hockeystick (HS) –Quadratic & Logistical Hockeystick(QHS,LHS)

SRR Reference Points

Fishery Management Is there a relationship between spawners & recruits? Would more data help? What is wrong?

No, No, It’s the ocean Smolt to adult survival ranged from 1% to 10%, or by a factor of 10

Possible Solutions Annual recruitment adjustment based on marine survival index (climate, hatchery steelhead survival, wild steelhead survival) Covariate (climate, hatchery or wild steelhead survival) into SRR –Two Stage SRR R = aS/(1+ aS/B) * MS - Hatchery smolt survival R = aS/(1+ aS/B) * (HS) c

Possible Solutions (continued) PDO or other ocean/climate index PDO adjusted for smolt outmigration year

Fishery Management Objectives Maximize Harvest? –Maximum Sustainable Yield (MSY) –MSY as lower bound Maximize fishing opportunity (C&R)? Maximize/maintain Freshwater Production? –S* = minimum escapement to maximize smolt yield –½ K = freshwater 50% of capacity Maintain Genetic Diversity? –500 spawners –WSP / average maturity (600 spawners)

Wind River MSY objectives

Summary MSY goals for low (3%)ocean survival MSY goals for hi (6%) ocean survival MSY goals for avg(4.5%)ocean survival MSY goals are highly variable depending on SAS (1%) to 1192(10%) Precautionary approach suggest MSY as lower bound MSY goals for small steelhead populations may compromise genetic diversity

Summary Current Wind River escapement goal 1,000 to 1,300 based on habitat model with good marine survival MSY goals for 4.5% SAS Minimum genetic goal spawners SRR goals freshwater productivity (517 – 729) –Beverton-HoltHockeystick ½ K = 729 S* = 532, S* for QHS = 517

Fishery Management Wind River Steelhead are listed under ESA Currently, WDFW manages steelhead commercial & recreational fishery impacts in the Wind River and other Lower Columbia River populations for less than 10% Fishery management and escapement objectives for Wind River will be a compromise of science and policy Recovery planners advocate “extra spawners” (above MSY) to take advantage of habitat restoration or lessen extinction risk

Fishery Management When fisheries are managed for fixed escapement goals, they are more likely to meet escapement objectives When fisheries are managed for fixed harvest rates, they are more likely to meet fishing objectives If we desire more precise management, a fishery management with multiple thresholds or controls between 300 and 800 adults could be developed for this population (BC approach with conservation and target reference points)