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Forecast of Adult Returns



Ocean Indicators Home

2007 Annual Update

Forecast of Adult Returns

Large–scale Ocean and Atmospheric Indicators

 • Pacific Decadal Oscillation (PDO)
 • Multivariate El Nino Southern Oscillation Index (MEI)
 • Basin-Scale Winds

Local and Regional Physical Indicators

 • Sea Surface Temperature Anomalies
 • Coastal Upwelling
 • Physical Spring Transition
 • Deep Water Temperature and Salinity

Local Biological Indicators

 • Copepod Biodiversity
 • Northern Copepod anomalies
 • Copepod Community Structure
 • Biological Spring Transition
 • June Spring Chinook
 • September Coho
 • Zooplankton Species Composition

Indicators Under Development

 • A Second Mode of North Pacific Sea Surface Temperature Variation
 • Phytoplankton Biomass
 • Euphausiid Egg Concentration, Adult Biomass, and Production Rates
 • Interannual Variations in Habitat Area
 • Forage Fish and Pacific Hake Abundance
 • Salmon Predation Index
 • Potential Indices for Future Development

Introduction to Pacific Northwest Oceanography

 • Physical Oceanographic Considerations
 •  Climate–scale Physical Variability

Ocean Sampling Methods

 • Hydrography, Zooplankton, and Ichthyoplankton
 • Juvenile Salmon Sampling

Acknowledgements

References

Archive of Updates and Forecasts

Links

Glossary

 


Forecast of Adult Returns for Coho in 2008 and
Chinook Salmon in 2009


From the colorized table below, one can see that the recent 3–year period of poor ocean conditions (2003–2005) has come to a close, with improving conditions in 2006 and greatly improved conditions in 2007.  Indicators and their values were evaluated by year, with color assigned based on rank among the past 10 years (see charts below).  For example, in 2007 average sea–surface temperatures in summer at NOAA Weather Buoy 46050 were the 9th highest of the past 10 years (indicating poor upwelling of cooler, nutrient–rich waters).  Thus the SST at NOAA Buoy 46050 was ranked 9th in 2007.  Low ranks indicate better conditions and higher ranks worse conditions for salmon.  The ranking system is shown in greater detail below, but in brief, ranks of 1–4 were coded green, 5–6 yellow, and 7–10 red. 


      Table 1.  Ocean ecosystem indicators of the Northern California Current.  Colored squares indicate positive (green), neutral (yellow), or negative (red) conditions for salmon entering the ocean each year.  In the two columns to the far right, colored dots indicate the forecast of adult returns based on ocean conditions in 2007.     
 
 
 

Juvenile
migration year

 

Forecast of adult returns

 
2000

2005

2006

2007
  Coho
2008
Chinook
2009
 
Large–scale ocean and atmospheric indicators
Pacific Decadal Oscillation (PDO)  
Multivariate El Nino Southern Oscillation Index (MEI)  
 
Local and regional physical indicators      
Sea surface temperature anomalies  
Coastal upwelling  
Physical spring transition  
Deep water temperature and salinity  
 
Local biological indicators     
Copepod biodiversity  
Northern copepod anomalies  
Biological spring transition  
June spring Chinook   ––
September Coho   ––
 
    Key good conditions for salmon    good returns expected
     intermediate conditions for salmon    –– no data
     poor conditions for salmon    poor returns expected

Most indicators in 2007 pointed toward greatly improved ocean conditions compared to the previous few years.  Indicators that point to good salmon survival included a cold ocean in winter/spring 2007, an early spring transition date, high biomass of cold–water lipid–rich copepods, and a long upwelling season.  Negative indicators included weak upwelling in late spring and summer, very warm sea surface temperatures, and low catches of juvenile coho in September surveys. 

The chart below provides more information about the color coding used in Table 1.  Again, lower numbers indicate better conditions, or "green lights" for salmon growth and survival, with ranks 1–4 green, 5–6 yellow, and 7–10 red.  To arrive at these rank scores, the past 10 years of sampling data were compared among one another.  Thus for each indicator, a given year will receive a rank score between 1 and 10.

Naturally, these scores are assigned based on the type of data collected.  For example, higher sea–surface temperatures in summer translate to higher (worse) rank scores, while higher catches of coho in September will receive lower (better) rank scores.

In future years, as more data are collected, the range of possible scores will increase.  Note also that some indicators have 2 years with the same score.  For example, among all years for which we have data, the best in terms of deep–water temperature was a tie between 2001 and 2002.  Thus there are two ranks of 1 and no rank of 2 for this indicator.

To generalize conditions for each year, the sum of all the rank scores for that year is divided by the number of indicators observed in that year.  Mean ranks are then compared among years to give a generalized concept of "good" vs. "bad" ocean conditions for salmon in a given year. 


 
 

Year of Samples

  1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
 
Large–scale ocean and atmospheric indicators
Pacific Decadal Oscillation (PDO)
7 1 2 3 4 9 8 10 6 5
Multivariate El Niño Southern Oscillation Index (MEI)
   May–Sep 10 1 2 4 9 8 6 7 5 3
   Jan–Jun 10 1 2 4 6 8 5 9 3 7
 
Local and regional physical indicators
Sea surface temperature
   Buoy 46050 8 1 3 4 2 6 10 7 5 9
   NH 05 7 2 1 3 5 6 10 9 4 8
   Winter 10 5 3 4 2 6 9 8 7 1
Coastal upwelling 5 1 9 3 4 8 7 10 5 2
Phys. spring transition 9 1 7 4 2 6 8 10 3 5
Deep water at NH 05 (May–Sep)
   Temperature 10 3 5 1 1 6 7 9 8 4
   Salinity 10 2 2 4 7 8 9 6 5 1
 
Local biological indicators
Copepod biodiversity 10 2 1 4 3 7 6 9 8 5
N Copepod anomalies 10 7 2 4 1 8 5 9 6 3
Biol. spring transition 10 4 1 4 3 8 6 9 7 2
Upwelling Season Length 10 2 4 2 1 7 8 9 6 5
Spring Chinook 9 1 2 7 4 6 8 10 5 3
Coho 8 2 1 4 3 5 10 9 6 7
 
Overall Ranking
   Mean of ranks 8.9 2.3 2.9 3.7 3.6 7.0 7.6 8.8 5.6 4.4
   Rank of mean ranks 10 1 2 4 3 7 8 9 6 5
 
 Adult Returns by Year of Ocean Entry¹
  1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
 Coho Adult Survival²
  9 6 1 4 2 3 8 7 5 10
 Spring Chinook at Bonneville Dam
  4 1 2 3 5 7 6 8 -- --
  Fall Chinook at Bonneville Dam³
  7 5 3 1 2 4 6 8 -- --
 Fall Chinook entering the Klamath River (est)
  1 5 3 4 7 6 8 2 9 --
 
¹ Ranks lagged by 1 and 3 years for coho and Chinook, respectively.
² Coho ranking for 2007 estimated from jack returns.
³ Adult returns of fall Chinook have not yet been analyzed in terms of ocean ecosystem indicators.

Note from the adult return data above that the 4–year period of cold ocean conditions (1999–2002) resulted in good returns of Chinook salmon.  In contrast, the warm ocean conditions from 2003 to 2006 correspond with declining returns.  We expect at least one more year of poor returns from this period, after which returns should begin to increase, so long as the cold ocean conditions observed in 2007 continue into 2008 and beyond.

Coho Salmon—Although the indicators were sending very mixed messages overall, we expect improved survival for coho that went to sea in 2007 (and which will return in fall 2008) as compared to the past few years.  As an example of the range in estimated return rates for OPIH fish among different indicators, a regression of return rates of coho salmon vs. catches of coho in September surveys suggests only 2% of the coho will return in 2008.  However, the relatively early transition of the zooplankton community in spring, and the high biomass of cold–water zooplankton species suggest an adult return rate closer to 4.1%, a much larger proportion. 

Chinook Salmon—Ocean conditions at the time of ocean entry and through the month of May 2007 were very good.  Since spring Chinook juveniles reside in waters off Oregon and Washington for only a few weeks before migrating north to unknown waters, their survival might have been relatively well supported by these conditions.  These fish could begin to return as early as spring 2009. 

Data used in the rank scores above are shown in the chart below.  Note that counts of spring and fall Chinook salmon at Bonneville Dam are shown lagged by 3 years.  For example, the number listed for 1998 indicates fish that returned in 2001.  This lag in timing is used because Chinook lives in the ocean for 1–5 years before returning to freshwater. For coho, the ocean life is 1–3 years; thus a lag of only 1 year is used.


 
  1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
 
PDO (May–Sep)  0.9 –5.54 –3.23 –2.95 –0.47  3.42  2.21  3.94  0.28  0.18
MEI (annual) 0.87 –0.85 –0.51 –0.18 0.59 0.46 0.38 0.40 0.22 –0.20
MEI (Jan–Jun) 2.28 –0.80 –0.63 –0.28 0.32 0.55 0.27 0.65 –0.42 0.49
Sea Surface Temperature (°C)
   Buoy 46050 13.70 12.54 12.56 12.30 12.92 14.59 13.43 12.60 13.88
   NH 05:  summer 11.34 10.89 10.62 10.91 11.14 11.2 12.99 12.24 11.02 11.55
   NH05:  winter pre-entry 12.11 10.52 10.26 10.31 10.01 10.81 11.32 11.07 10.92 9.96
   NH05:  Winter post-entry 10.52 10.26 10.31 10.01 10.81 11.32 11.07 10.92 9.96
Physical Spring Transition (Julian date) 187 119 142 129 120 141 157 209 123 136
Coastal Upwelling Anomalies (Apr–May) –14  19 –36  2 –12 –34 –27 –55 –14  9
Deep water (50 m)
   NH 05 Temp (°C) 8.58 7.51 7.62 7.5 7.5 7.76 7.87 7.93 7.91 7.55
   NH 05 Salinity 33.51 33.87 33.87 33.86 33.78 33.7 33.67 33.80 33.82 33.88
Copepod Biodiversity (No. species) 5.49 –2.46 –3.03 –0.41 –0.72  1.52  0.57  5.02  3.67 –0.39
N. Copepod Anomalies (log biomass) –2.09 –0.04  0.59  0.36  0.71 –0.21  0.14 –1.90  0.04  0.49
Biological Spring Transition (Julian date) never 114 76 114 100 166 130 200 164 88
Length of the Upwelling Season (d) 0 174 195 196 176 120 114  33 154 196
June Chinook Catches (fish/km) 0.27 1.27 1.04 0.44 0.85 0.63 0.42 0.13 0.68 0.87
September Coho Catches (fish/km) 0.11 1.12 1.27 0.47 0.98 0.29 0.07 0.03 0.16 0.15
 
  Adult returns by Year of Ocean Entry¹
  1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
OPIH Coho (adults:smolts) 0.0128 0.0209 0.0460 0.0258 0.0399 0.0281 0.0177 0.0196 0.219 0.0095²
Spring Chinook at Bonneville (n) 177,741 391,367 268,813 192,010 168,656 74,038 96,456 66,624    
Fall Chinook at Bonneville (n) 192,793 400,205 473,786 610,075 583,224 415,684 299,161 157,784    
Est. fall Chinook entering Klamath R. (n) 617,573 357,085 514,524 401,092 160,243 190,568  88,652 521,412  31,600²  
 
¹Chinook numbers are lagged by 3 years, and coho ratios by 1 year.
²Estimate based on jack returns.











last modified 03/11/2008

              
   
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