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Stability of Pacific herring in Puget Sound is 2x what it would be without habitat and population diversity.
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Population diversity in Puget Sound herring: Is there a “portfolio effect”?
Tessa Francis, University of Washington Tacoma Megsie Siple, University of Washington
Daniel Schindler, University of Washington Washington Department of Fish and Wildlife
• Pacific herring in Puget Sound are declining, causes unknown. • 21 different sub-populations, associated with shoreline sections. • Shoreline armoring is increasing. • Do we increase stability of the population by keeping all
sub-populations? YES
THERE IS A PORTFOLIO EFFECT ✔
Redorbit.com!BRANDON COLE / WWW.BRANDONCOLE.COM!
Forage fish provide multiple ecosystem services globally
The mysterious decline of "Puget Sound herring"
Forage fish support iconic Puget Sound species
Puget Sound herring have declined in recent decades
0
3,000
6,000
9,000
12,000
15,000
18,000
1973 1978 1983 1988 1993 1998 2003 2008 2013 2018
TON
S
YEAR
Cherry Pt. Squaxin
Adult spawner biomass Based on egg deposition surveys Source: WA Department of Fish and Wildlife
Puget Sound herring are tightly linked to the shoreline
Paul Hanson, NOAA
Map: Blake Feist, NOAA NWFSC
Puget Sound Shoreline Armoring
Shoreline armoring is increasing.
Does population diversity increase stability of Puget Sound herring?
Mid/small cap stocks
Large cap stocks
Balanced fund
Cash
The Portfolio Effect: Diversity increases stability
1 2
3
Age diversity
0. 01
0. 1
1
10
1
Major rivers
0. 01
0. 1
1
10
1
Streams
0. 01
0. 1
1
10
1
All the same age
0. 01
0. 1
1
10
1
year
Total return (rela;
ve)
Bristol Bay
1960 2010
Herring subpopulations can contribute 2-5x the average in good years.
Puget Sound herring subpopulations are not highly synchronous
The Puget Sound herring population is less variable than the individual subpopulations
Bio
mas
s (s
tand
ardi
zed)
1980 2010
Log(
Varia
nce)
Log(Mean)
z = 2.1
expected
observed
The Puget Sound herring population is two times more reliable than the individual components of the portfolio
Anderson et al. Methods Ecol. Evol. In Press
No change
Decrease Increase
Eelgrass bed trends (2004-‐2009)
33% of shoreline altered
25% of shoreline armored
2005-‐2010 Rate of new armoring: 1.8 km/yr
Are Puget Sound herring habitat limited?
Marc Mangel Tim Essington Alec MacCall Doug Hay Paul Hershberger Dayv Lowry Ole Shelton Tessa Francis
Study Panel on Ecosystem Based Management of Puget Sound Forage Fish
1. Status and trends 2. Key Vulnerabilities 3. Ecosystem Needs
