Portfolio Effect in Puget Sound Herring: ESA 2013 Minneapolis
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
THERE IS A PORTFOLIO EFFECT ✔
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Forage fish provide multiple ecosystem services globally
The mysterious decline of "
Puget Sound herring"
Puget Sound herring have declined in recent decades
1973 1978 1983 1988 1993 1998 2003 2008 2013 2018
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
Shoreline armoring is
Does population diversity
increase stability of Puget Sound herring?
Mid/small cap stocks
Large cap stocks
The Portfolio Effect: Diversity increases stability
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
z = 2.1
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
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