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

Hypotheses

• Repeat spawners will have more 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?

Hypotheses• Repeat spawners will have more

offspring than one-time spawners

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

Hypotheses• Repeat spawners will have more

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 offspring the second time they spawn than the first time

Snow Creek

Strait of Juan De Fuca

Port Townsend

Discovery B

ayBarrier waterfall

~5 km

Study site: Snow Creek

Oncorhynchus mykiss

Photo: Thom Johnson

Snow Creek

Strait of Juan De Fuca

Port Townsend

Discovery B

ay

Permanent weir - WDFW

~5 km

Snow Creek

Strait of Juan De Fuca

Port Townsend

Discovery B

ay

No hatchery*

~5 km

Snow Creek

Strait of Juan De Fuca

Port Townsend

Discovery B

ay

~5 km

Snow Creek

Strait of Juan De Fuca

Port Townsend

Discovery B

ay

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

1401

98

2

19

83

19

84

19

85

19

86

19

87

19

88

19

89

19

90

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

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 years

N (parents + adult offspring) = 1094

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 years

N (parents + adult offspring) = 1094

• Scales • Fin Clip

1986 1987 1988 2004Parental brood year

1982

1983

1984

Adult offspring sample year

Directly enumerate number of adult offspring returning to spawn

2000

1989

Genetically match parents to returning adult offspring

How were repeat spawners identified?

• Healed opercle scar

• Healed opercle scar

• Scales– Spawn check

Spawn check

Photo: Michael Dauer

How were repeat spawners identified?

• Healed opercle scar

• Scales– Spawn check

Spawn check

Photo: Michael Dauer

How were repeat spawners identified?

• Healed opercle scar

• Scales– Spawn check

• DNA

Female - 1988

Female - 1989

How were repeat spawners identified?

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

pro

po

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

offspring than one-time spawners

• 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

rag

e #

off

spri

ng

± 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

1.2 offspring / male

Ave

rag

e #

off

spri

ng

Spawner type

N=383 N=19

± 1

SE

t-test, p=0.05

Hypotheses• Repeat spawners will have more adult

offspring than one-time spawners

• 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

rag

e #

off

spri

ng

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

1.2 offspring / male

Ave

rag

e #

off

spri

ng

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)

Pro

po

rtio

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

Re

lati

ve

re

pro

du

ctiv

e s

ucc

ess

smaller bigger

Relative length

P < 0.01

r2 = 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

ela

tiv

e r

ep

rod

uct

ive

su

cce

ss

smaller bigger

Relative length

P < 0.01

r2 = 0.01

Consistent repeat spawning rates

• across Washington rivers

River Run % x 1 % x 2 % x 3

Skagit Winter 92 7 1

Snohomish Winter 92 6 1

Green Winter 93 7

Puyallup Winter 89 10

Nisqually Winter 93 6 1

Quillayute Winter 91 7 1

Cowlitz Winter 96 4

Kalama Winter 93 6

Kalama Summer 94 6

Source: Busby et al. 1996

Snow Creek rates are about the same

River Run % x 1 % x 2 % x 3

Skagit Winter 92 7 1

Snohomish Winter 92 6 1

Green Winter 93 7

Puyallup Winter 89 10

Nisqually Winter 93 6 1

Quillayute Winter 91 7 1

Cowlitz Winter 96 4

Kalama Winter 93 6

Kalama Summer 94 6

Snow 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

19

82

19

83

19

84

19

85

19

86

19

87

19

88

19

89

19

90

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

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

Se

x 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

Fre

qu

ency

Males

Females

Uneven distribution of adult offspring among parents

average = 0.91

σ2 / μ2 = 2.67

Pro

po

rtio

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

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Mother Father

1998

1999

2000

Mothers Fathers

Mothers Fathers

0.70

0.60

0.50

0.40

0.30

0.20

0.10

0

0.70

0.60

0.50

0.40

0.30

0.20

0.10

0

Pro

po

rtio

n

Pro

po

rtio

n

mature male parr

~30%

~30%