Stephanie Carlson1 and William Satterthwaite2

1 Department of Environmental Science, Policy & Management, UC Berkeley2 NOAA-Fisheries, Santa Cruz

Managing for population diversity and stability: examples and potential hatchery applications

Cal-Neva AFS Annual Meeting, Sacramento: March 27, 2014

Small streams

(low water levels lead to stranding mortality,

intense bear predation)

Large rivers

(stable flows, minimal bear predation)

Lake beaches

(spawning occurs where there is upwelling or wind driven currents, no bear predation, large gravels)

Photo credits: N. Kendall, T. Quinn, A. Hendry

Among population variation in:• phenology,• age complexity & degree of overlapping generations, • fecundity

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

45,000,000

1893 1904 1915 1926 1937 1948 1959 1970 1981 1992

Cat

ch

Naknek-Kvichak

Nushagak

Egegik

Variation among populations

Photo credits: T. Quinn

The biocomplexity of the stock structure has also played an critical role inproviding stability and sustainability. Here we provide evidence for the effects of biocomplexity on sustainability and emphasize that conserving biocomplexity within fish stocks is important for maintaining their resilience to future environmental change. – Hilborn et al. 2003, p. 6564

Hilborn et al. 2003. Biocomplexity and fisheries sustainability. Proceedings of the National Academy of Sciences 100: 6564-6568.

Portfolio effect

ECONOMICS1. Portfolio of financial assets2. Invest in diverse assets

Combination of multiple, diverse assets minimizes performance risk of the portfolio

ECOLOGY1. Portfolio of populations within a complex2. Manage for diverse phenotypes

Combination of multiple, diverse populations minimizes performance risk of the portfolio

0

100,000

200,000

300,000

400,000

500,000

600,000

1955 1965 1975 1985 1995 2005

Quantifying buffering induced by the PE

Pop1

Pop2

Coefficient of variation (S.D. / mean)

Pop1 = 99871 / 198817 = 0.502Pop2 = 74600 / 138757 = 0.538

Adult production

(escapement + catch)

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

1955 1965 1975 1985 1995 2005

Quantifying buffering induced by the PE

Pop1

Pop2Adult production

(escapement + catch)

Pooled (total) returns

Coefficient of variation (S.D. / mean)

Pop1 = 99871 / 198817 = 0.502Pop2 = 74600 / 138757 = 0.538Pooled returns = 129650 / 337574 = 0.384

Synchronous population dynamics0

10

03

00

50

07

00

1960 1970 1980 1990 2000 2010

A

Mainstem Sac.BattleFeatherYubaAmerican

01

02

03

04

05

06

07

08

0

1960 1970 1980 1990 2000 2010

B

MokelumneStanislausTuolumneMercedA

dult

prod

uctio

n (t

hous

ands

)

• 6 / 6 pairwise correlations were positive, 4 of these were significant

• 8 / 10 pairwise correlations were positive, 4 of these were significant

Sacramento Basin

San Joaquin Basin

1957 1962 1967 1972 1977 1982 1987 1992 1997 2002 2007

20

04

00

60

08

00

10

00

12

00

14

00

20

04

00

60

08

00

10

00

12

00

14

00

Adu

lt pr

oduc

tion

(tho

usan

ds)

Sacramento Basin

San Joaquin Basin

Uneven abundance

Habitat diversity

Phenotypic diversity

Diverse (asynchronous) population dynamics

Stabilizing portfolio effect

BRISTOL BAY SALMON Recent research1 has revealed salmon returns to Bristol Bay were 41-77% more stable depending on the scale of aggregation (as measured by reduction in coefficient of variation in production), than the variability in individual stocks

1 Schindler et al. 2010. Population diversity and the portfolio effect in an exploited species. Nature 465: 609-612.

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

45,000,000

1893 1904 1915 1926 1937 1948 1959 1970 1981 1992

Cat

ch

Naknek-Kvichak

Nushagak

Egegik

Spawning Adult

Eggs

Fry

Smolt

Ocean Sub-Adult

Mature Adult

FRESHWATERMARINE

Slide courtesy of C. Phyllis, artwork by J. Moore

Migration date

Timing of ocean entry:Match-mismatch dynamics

Prey availability

Habitat diversity

Phenotypic diversity

Diverse (asynchronous) population dynamics

Stabilizing portfolio effect

Extensive outplanting of hatchery-produced salmon smolts

Merced River

http://www.fisheryfoundation.org/

San Pablo Bay

In 2008, 20.2 million smolts outplanted to San Pablo Bay!

Nimbus Hatchery on the American River

Homogenizing influence of hatcheries

• Simplified life histories (e.g., functional semelparity in steelhead)

• Simplified age structure (age/stage at release, age at maturity)

• Simplified size and timing of release

Central Valley Chinook life history diversity

Habitat diversity

Phenotypic diversity

Diverse (asynchronous) population dynamics

Stabilizing portfolio effect

Habitat lost (e.g., due to dams) and simplified (e.g., due to levees)

Life history homogenization

Synchronous population dynamics

Instability, high risk of collapse

BRISTOL BAY SALMON CENTRAL VALLEY SALMONVS.

Hatchery mgmt