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

Thanks!

tessa@uw.edu @tessafrancis