Todd Seamons and Tom Quinn University of Washington School of Aquatic and Fishery Sciences

Todd Seamons and Tom QuinnUniversity of Washington

School of Aquatic and Fishery Sciences

Individual lifetime reproductive success of repeat spawners vs. one-

time spawners

Hypotheses• Repeat spawners will have more

offspring than one-time spawners– In terms of lifetime reproductive success


offspring than one-time spawners– In terms of lifetime reproductive success

• But repeat spawning fish don’t just age between brood years, they also grow

Female choiceDominance

Body Size

Longevity

MalesReproductive success

Hypothesized size advantages for repeat spawners

Egg SizeFecundity

Body Size

Redd Quality

FemalesReproductive success

Hypothesized size advantages for repeat spawners

Other advantages?

• Prior knowledge/experience?– Females

• Best redd sites

– Males• Spawning territories?


offspring than one-time spawners

• Repeat spawners will produce more than twice the average number of offspring of one-time spawners



• Repeat spawners will produce more than twice the average number of offspring of one-time spawners

• Repeat spawners will produce more offspring the second time they spawn than the first time

Snow Creek

Strait of Juan De Fuca

Port TownsendDiscovery BayBarrier waterfall

~5 km

Study site: Snow Creek

Oncorhynchus mykiss

Photo: Thom Johnson

Snow Creek


Port TownsendDiscovery Bay

Permanent weir - WDFW

~5 km

Snow Creek



No hatchery*

~5 km

Snow Creek



~5 km

Snow Creek



No fishing!

~5 km

Adults trapped and sampled at the weir

Sampling

• Date• Sex• Fin clip (DNA)• Fork Length (mm)• Scales (DNA, age – Jon Sneva, WDFW)

6

143

0

20

40

60

80

100

120

14019

8219

8319

8419

8519

8619

8719

8819

8919

9019

9119

9219

9319

9419

9519

9619

9719

9819

9920

00

Brood Year

Total number of adults returning to Snow Creek in 19 brood years

Brood Year

N (M

+F)

1986 1987 1988 2004Parental brood year

1982

1983

1984

Adult offspring sample year

Directly enumerate number of adult offspring returning to spawn

2000

1989

19 parental brood yearsN (parents + adult offspring) = 1094


1982

1983

1984



2000

1989

19 parental brood yearsN (parents + adult offspring) = 1094

• Scales • Fin Clip


1982

1983

1984



2000

1989

Genetically match parents to returning adult offspring

How were repeat spawners identified?

• Healed opercle scar


• Scales– Spawn check

Spawn check

Photo: Michael Dauer



• Scales– Spawn check

• DNA

Female - 1988

Female - 1989


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Females Males

More females survive to kelt than malesA

vera

ge p

ropo

rtio

n Range: 56-91%

64% overall survival to kelt (11 years of data)

54%

74%

Range: 31-84%

Snow Creek repeat spawner growth

• Growth– Female average = 42 mm (n = 16)– Male average = 71 mm (n = 3)

• Fecundity– +350 – 450 eggs – A little over 10% increase in fecundity

0.0694033*[Length]^1.66088 – Thom Johnson personal comm.

Hypotheses• Repeat spawners will have more adult


• Repeat spawners will produce more than twice the average number of adult offspring of one-time spawners

Repeat spawning females have only twice the number of adult offspring as single-time spawners

0.0

0.5

1.0

1.5

2.0

2.5

Single Repeat

0.9 offspring / female

1.8 offspring / female

Ave

rage

# o

ffspr

ing

± 1

SE

Spawner type

N=380 N=54

t-test, p=0.001

Repeat spawning males have a little more than twice the number of adult offspring as single-time spawners

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Single Repeat

0.5 offspring / male


Ave

rage

# o

ffspr

ing

Spawner type

N=383 N=19

± 1

SE

t-test, p=0.05

Hypotheses• Repeat spawners will have more adult


• Repeat spawners will produce more than twice the average number of adult offspring of one-time spawners

• Repeat spawners will produce more adult offspring the second time they spawn than the first time

Repeat spawning females produced slightly more adult offspring their second spawning

0.0

0.2

0.4

0.6

0.8

1.0

1.2

First Second

0.8 offspring / female0.9 offspring / female

Ave

rage

# o

ffspr

ing

Spawning Year

N=54 N=54

± 1

SE

Not significantly different

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

First Second

Repeat spawning males produced all of their adult offspring their second spawning

0 offspring / male


Ave

rage

# o

ffspr

ing

Spawning Year

N=19 N=19

± 1

SE

Summary - males• Repeat spawning male LRS = x2.4 one-

time spawners• First time spawning males produce no

adult offspring

• Life-history trade off for males?– sacrifice present reproduction for future

Summary - females• Repeat spawning female LRS = x2 one-

time spawners• In any one year, a repeat spawning

female is only as good as a one-time spawning female

• No obvious trade-off for females

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

275

320

365

410

455

500

545

590

635

680

725

770

815

860

Length (mm)

Prop

ortio

n Not all repeat spawners are big

Repeat spawners @ 2nd time spawningAll adults

0

5

10

15

20

25

30

35

40

-5 -4 -3 -2 -1 0 1 2 3 4

Rel

ativ

e re

prod

uctiv

e su

cces

s

smaller biggerRelative length

P < 0.01r2 = 0.01

Bigger is better for males (but not much)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

-6.0 -4.0 -2.0 0.0 2.0 4.0 6.0

Bigger is better for females (but not much)R

elat

ive

repr

oduc

tive

succ

ess

smaller biggerRelative length

P < 0.01r2 = 0.01

Consistent repeat spawning rates• across Washington rivers

River Run % x 1 % x 2 % x 3Skagit Winter 92 7 1Snohomish Winter 92 6 1Green Winter 93 7Puyallup Winter 89 10Nisqually Winter 93 6 1Quillayute Winter 91 7 1Cowlitz Winter 96 4Kalama Winter 93 6Kalama Summer 94 6

Source: Busby et al. 1996

Snow Creek rates are about the same

River Run % x 1 % x 2 % x 3Skagit Winter 92 7 1Snohomish Winter 92 6 1Green Winter 93 7Puyallup Winter 89 10Nisqually Winter 93 6 1Quillayute Winter 91 7 1Cowlitz Winter 96 4Kalama Winter 93 6Kalama Summer 94 6Snow Creek Winter 88 10 2

Source: Busby et al. 1996

• but much smaller population

• Would removal = fewer in the future?

Probably NOT

• Genetic component of repeat spawning ≈ 0

• Repeat spawning = almost all environmental– Spawning conditions– Flow at outmigration– Migration distance– Ocean conditions upon arrival– Ocean conditions for the next year

Is it important to keep repeat spawners in the population?

Is it important to keep repeat spawners in the population?

• Repeat spawning = Overlapping generations– Slow the rate of loss of genetic diversity

• Important for population recovery– Increased rate of recovery for small

populations

Many many many many thanks…

• Thom Johnson WDFW• Randy Cooper WDFW• Cheri Scalf WDFW• Jon Sneva WDFW• Many volunteers

Many Thanks…• In the field

– Jen McLean– Caryn Abrey– Ray Timm– Josh Latterell– Greg Mackey– Ian Stewart– Erin McClelland– Chris Boatright– Et al.

• MMBL– Sofia– Jen McLean– Mike Canino– Tatiana Rynearson– Patrick O’Reilly– Rolf Ream– Pam Jensen– Brent Vadopalas– Ingrid Spies– Sara Feser– Jennifer Cabbarus– Anny Soon– Ann Riddle– Willy Eldridge– Erin McClelland– Et al.

• Funding– National Science Foundation– H. Mason Keeler Endowment

• Data Analysis– Kevin Brinck– Stephanie Carlson

• The Quinn Group– Jen McLean– Caryn Abrey– Bobette Dickerson– Stephanie Carlson– Richie Rich– Et al.

6

143

0

20

40

60

80

100

120

140

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

Brood Year

N

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

Total number and sex ratio of adults returning to Snow Creek in 19 brood years

Brood Year

N (M

+F)

2:1

1.5:1

1:1

1:1.5

1:2

1:2.5

3:1

2.5:1

Sex ratio+F +M

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0 1 2 3 4 5 6 7 8

Freq

uenc

y

MalesFemales

Uneven distribution of adult offspring among parents

average = 0.91

σ2 / μ2 = 2.67

Prop

ortio

n

19 brood years

# adult offspring per parent

average = 0.52

σ2 / μ2 = 4.59

Embryos

Juveniles

Smolts

AdultsOcean

Freshwater

Mature male parr

More mothers assigned

than fathers

3 brood years

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Mom Dad

19 brood years

00.10.20.30.40.50.60.7

Mother Father

199819992000

Mothers Fathers

Mothers Fathers

0.700.600.500.400.300.200.10

0

0.700.600.500.400.300.200.10

0

Prop

ortio

n

Prop

ortio

n

mature male parr

~30%

~30%

Todd Seamons and Tom Quinn University of Washington School of Aquatic and Fishery Sciences

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