reduced recruitment performance in natural populations of anadromous salmonids associated with...
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Reduced Recruitment Performance in Natural
Populations of Anadromous Salmonids Associated with
Hatchery-reared Fish
Pacific Coast Steelhead Meeting – March 14, 2012
Mark Chilcote (USFS), Kevin Goodson (ODFW), Matthew Falcy (ODFW)
Oregon Recovery Planning
Quantitatively describe threat impacts to viability
Hatchery threat difficult to describe
Literature review of limited help
Studies of Reproductive Success (RSh)
Number of offspring produced per hatchery spawner relative to number produced per wild spawner
Evidence from 3 studies (all steelhead): Leider et al 1990 (Kalama River) McLean et al 2003 (Forks Crk,
Washington) Araki et al 2007 (Hood River)
RSh averaged about 0.10 for segregated stocks and 0.60 for integrated stocks
Supposition
IF reproductive success of hatchery fish (RSh) spawning in the wild is low,
THEN, should see evidence of this from recruitment performance
Relationship from Chilcote 2003*
y = -1.97x + 1.41R2 = 0.70
-0.50
0.00
0.50
1.00
1.50
0.00 0.25 0.50 0.75 1.00
Ph
Intr
insi
c P
rod ..
* Chilcote, M.W. 2003. Relationship between natural productivity and the frequency of wild fish in mixed spawning populations of wild and hatchery steelhead (Oncorhynchus mykiss). Can. J. Fish. Aquat. Sci. 60: 1057-1067
2011 Analysis – Key Questions
Does relationship hold for all populations?
Does it apply to other species (coho and Chinook)?
Is it sensitive to type of hatchery fish? Integrated versus Segregated
Two-Step Process
1. Estimate intrinsic productivity through fitting recruitment curves to data sets
2. Determine what variables (covariates) account for most of the variation in intrinsic productivity
Recruitment Model Fits
Looked at 93 populations From Washington, Oregon, Idaho
Fit recruitment model for 89 of these
Therefore, intrinsic productivity estimated Chinook (37), steelhead (29), and
coho (23)
Populations Well Distributed
Step Two
Develop productivity models with multiple covariates
Compare models Identify model that best explains
variability
Covariates
Species Hatchery location Hatchery program type
(integrated/segregated) Hatchery legacy Dams Proportion hatchery spawners
(Ph)
Models Considered
Covariate
Model
12
9 1 7 8 11
10
4 2 6 3 5
Ph X X X X X X X
Species X X X X X X X X X X X X
H type X X X X X X X
H legacy X X X X X X X
H location
X X X X X X X X
Dams X X X X X X X X X
Ph:Species
X X X X X
Ph:H type
X
BIC 144
148
157
161
166
170
175
211
215
218
230
239
Best Model Covariates
Covariate Sum of Squares
Ph 41
Species 13
Dams 7
Hatchery location 2
Best model did not include hatchery type or legacy
Modeled Relationship
Chinook – Coho – Steelhead -
Findings
The model explained 72% of the variability in the data
The slope suggests that productivity of 100% hatchery fish is 13% that of 100% wild fish
There was no relationship with integrated versus segregated broodstocks
Mechanism(s) Unknown
Analyses didn’t identify mechanisms
Maybe a combination of: Plausible RSh levels (segregated
RSh = 0.10) Ecological effects Multigenerational accumulation of
adverse impacts Note that analysis is not for single
generation but for a period of 20 years (4 to 6 generations).
For Consideration
If: Impact from segregated or integrated is
the same, Loss of fitness Araki and others found is
universal, Ph would be the same regardless, and Hatchery program is for harvest;
Should you choose integrated?
Integrated Harvest Programs
Pros Maintains genetic
similarity to wild population
Mimics wild run timing
Anglers love them
Cons Reduces fitness in one
generation Difficult to meet goals
consistently More effort required
to collect brood Requires mining of
wild population
A Hypothesis to Explore
Naturally spawning integrated fish appear to produce more offspring than segregated
Could lead to more F1s, F2s to interbreed with wild population
Might lead to more alteration of the genetic composition of wild population
Fishery benefits could be maintained by managing run timing of segregated broodstock
Might be better off with segregated programs
Questions ?
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