Todd Seamons and Tom Quinn University 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 choice Dominance Body Size Longevity Males Reproductive success Hypothesized size advantages for repeat spawners

Egg Size Fecundity Body Size Redd Quality Females Reproductive 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 Bay Barrier waterfall ~5 km Study site: Snow Creek Oncorhynchus mykiss Photo: Thom Johnson

Snow Creek Strait of Juan De Fuca Port Townsend Discovery Bay Permanent weir - WDFW ~5 km

Snow Creek Strait of Juan De Fuca Port Townsend Discovery Bay No hatchery* ~5 km

Snow Creek Strait of Juan De Fuca Port Townsend Discovery Bay ~5 km

Snow Creek Strait of Juan De Fuca Port Townsend Discovery Bay 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)

Total number of adults returning to Snow Creek in 19 brood years Brood Year N (M+F)

Parental brood year Adult offspring sample year Directly enumerate number of adult offspring returning to spawn parental brood years N (parents + adult offspring) = 1094

Parental brood year Adult offspring sample year Directly enumerate number of adult offspring returning to spawn parental brood years N (parents + adult offspring) = 1094 Scales Fin Clip

Parental brood year Adult offspring sample year Directly enumerate number of adult offspring returning to spawn Genetically match parents to returning adult offspring

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 Spawn check Photo: Michael Dauer How were repeat spawners identified?

Healed opercle scar Scales –Spawn check DNA Female Female How were repeat spawners identified?

More females survive to kelt than males Average proportion 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 *[Length]^ – 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 0.9 offspring / female 1.8 offspring / female Average # offspring ± 1 SE Spawner type N=380N=54 t-test, p=0.001

Repeat spawning males have a little more than twice the number of adult offspring as single-time spawners 0.5 offspring / male 1.2 offspring / male Average # offspring Spawner type N=383N=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 0.8 offspring / female 0.9 offspring / female Average # offspring Spawning Year N=54 ± 1 SE Not significantly different

Repeat spawning males produced all of their adult offspring their second spawning 0 offspring / male 1.2 offspring / male Average # offspring Spawning Year 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

Length (mm) Proportion Not all repeat spawners are big Repeat 2 nd time spawning All adults

Relative reproductive success smallerbigger Relative length P < 0.01 r 2 = 0.01 Bigger is better for males (but not much)

Bigger is better for females (but not much) Relative reproductive success smallerbigger Relative length P < 0.01 r 2 = 0.01

Consistent repeat spawning rates across Washington rivers RiverRun% x 1% x 2% x 3 SkagitWinter9271 SnohomishWinter9261 GreenWinter937 PuyallupWinter8910 NisquallyWinter9361 QuillayuteWinter9171 CowlitzWinter964 KalamaWinter936 KalamaSummer946 Source: Busby et al. 1996

Snow Creek rates are about the same RiverRun% x 1% x 2% x 3 SkagitWinter9271 SnohomishWinter9261 GreenWinter937 PuyallupWinter8910 NisquallyWinter9361 QuillayuteWinter9171 CowlitzWinter964 KalamaWinter936 KalamaSummer946 Snow CreekWinter88102 Source: Busby et al 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?

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.

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 1:11:1 1:1.5 1:21:2 1:2.5 3:1 2.5:1 Sex ratio +F +M

Uneven distribution of adult offspring among parents average = 0.91 σ 2 / μ 2 = 2.67 Proportion 19 brood years # adult offspring per parent average = 0.52 σ 2 / μ 2 = 4.59

Embryos Juveniles Smolts Adults Ocean Freshwater Mature male parr

More mothers assigned than fathers 3 brood years 19 brood years MothersFathers MothersFathers Proportion mature male parr ~30%