Salmon & Steelhead Recovery Tracker

Siuslaw (Independent Population)

Analyses of viability criteria (adult abundance, persistence, productivity, distribution, diversity and habitat) are presented for each independent population. Trends in adult abundance and habitat condition are presented for dependent populations.

Oncorhynchus kisutch

Abundance

Annual estimates of the abundance of naturally-produced spawners for each population.

Spawning Year Nat. Origin Spawners 95% Confidence Interval Abundance Goal Proportion of Goal
2016 9,141 3,584 94,200 10.0%
2015 10,352 2,884 48,900 21.0%
2014 38,896 13,149 107,600 36.0%
2013 14,118 4,596 94,200 15.0%
2012 11,946 3,677 94,200 13.0%
2011 28,082 5,812 107,600 26.0%
2010 25,983 8,180 107,600 24.0%
2009 30,607 9,347 107,600 28.0%
2008 17,491 10,515 94,200 19.0%
2007 3,552 1,217 48,900 7.0%
2006 5,869 3,193
2005 16,907 6,633
2004 8,729 2,222
2003 29,003
2002 55,445
2001 10,606
2000 6,532
1999 2,980
1998 1,020
1997 501
1996 7,234
1995 6,161
1994 3,159

Evaluation Thresholds

Pass -the observed spawner abundance is > the marine survival-specific escapement target at least six times in any 12-year period.

Fail - the observed spawner abundance is > the marine survival-specific escapement target 5 times or less in any 12-year period.

Distribution

The manner in which adults (spawners) are distributed within the freshwater portion of a population's home range.

Metrics

1. The percentage of random, spatially balanced surveys that have more than 4 wild adult spawners/mile (percent occupancy)

2. Comparison of the spatial pattern of potential spawning distribution to that observed using SVB or other spatial statistics.

Spawning Year Sites Occupied Sites Total Percent Occupied Occupancy Goal
2016 12 15 80% 87%
2015 12 14 86% 87%
2014 9 12 75% 87%
2013 23 32 72% 87%
2012 19 24 79% 87%
2011 24 24 100% 87%
2010 22 25 88% 87%
2009 27 36 75% 87%
2008 8 9 89% 87%
2007 11 22 50% 87%
2006 10 24 42%
2005 35 39 90%
2004 23 37 62%
2003 38 41 93%
2002 34 44 77%
2001 27 41 66%
2000 29 46 63%
1999 16 38 42%
1998 3 36 8%

Evaluation Thresholds

Metric 1

Pass - the observed percent occupancy is greater than or equal to the marine survival-specific occupancy target at least six times in any 12-year period.

Fail - the observed percent occupancy is greater than or equal to the marine survival-specific occupancy target five times or less in any 12-year period.

Metric 2

Pass - the observed regularity ratio is not significantly different from a random distribution at least six times in any 12-year period.

Fail - the observed regularity ratio is significantly different from a random distribution at least six times in any 12-year period.

Diversity
  • 2007
    pass

Within-population diversity is the result of phenotypic differences among individuals. These differences provide the flexibility of the population as a whole to respond successfully to short-term environmental variations. They are also the basis by which populations are able to adapt and evolve as conditions within their home range go through changes that are more permanent.

Metric

The average of the 100-year harmonic mean of spawner abundance for each independent population, as forecast from a population viability model.

Analysis Year Harmonic Mean Goal
2007 10,320 1,200

Evaluation Thresholds

Pass - If 100-year harmonic mean of spawner abundance is greater than 1,200.

Fail - If 100-year harmonic mean of spawner abundance is less than or equal to 1,200.

Time Period Category Comment
2007 pass Goal met 1 of 1 years

Habitat
  • 2007
    fail

The amount of available high quality habitat for all freshwater life stages in each independent population, excluding the lakes populations.

Habitat condition is evaluated using population specific winter habitat surveys in the range of coho salmon. These surveys began in 2007 with the goal of surveying each independent population or dependent population group once every 5 years. Not all populations in the Coast Coho ESU have been surveyed for habitat at this time therefore some populations will display no habitat data.

Survey Year Miles Current 95% Confidence Interval Miles Goal Percent of Goal
2007 155.6 85.4 508 30.6%

Evaluation Thresholds

For a population to pass this criterion, the miles of high quality habitat (i.e. capable of producing > 2,800 smolts/mile) equals or exceeds the population-specific goals.

Time Period Category Comment
2007 fail Goal met 0 of 1 years

Persistence
  • 2007
    pass

The forecast probability of persistence for each independent population based on results from population viability analysis (PVA) models.

Analysis Year Average Probability Goal
2007 0.999 0.99

Discussion and Rationale

A persistence criterion of a 99% or greater probability of persistence significantly increases the likelihood that the ESU will remain viable under extreme marine survival conditions while providing substantial environmental, cultural, and economic benefits. Future analyses will be based on an average persistence value from the four PVA models developed by the TRT (Wainwright et al. 2008;Wainwright et al. 2006 poster).

Analysis

Because of the uncertainty of demographic effects at low population size, the TRT used two levels of "quasi-extinction" (1 and 50) to model persistence of the populations.

Evaluation Thresholds

For a population to pass this criterion it must have an average probability of persistence of 0.99 or greater as estimated by the four PVA models used by the TRT (Wainwright et al. 2008;Wainwright et al. 2006 poster).

Time Period Category Comment
2007 pass Goal met 1 of 1 years

Productivity

Annual estimates of the number of naturally produced recruits (progeny) per spawner (parent) (R/S) in the population.

Spawning Year R/S
2016 0.71
2015 1.10
2014 1.58
2013 0.64
2012 0.50
2011 1.70
2010 7.54
2009 5.16
2008 1.03
2007 0.46
2006 0.22
2005 0.32
2004 0.89
2003 4.83
2002 18.26
2001 7.95
2000 10.10
1999 0.28
1998 0.15
1997 0.11

Evaluation Thresholds

Pass - Over a 12-year period, R/S values, standardized to a spawner density equal to the spawner abundance goal for each marine survival category, are statistically greater than or equal to 1.0.

Fail - Over a 12-year period R/S values, standardized to a spawner density equal to the spawner abundance goal for each marine survival category, are statistically less than 1.0.