Demography of southern leatherside chub in the presence and absence of an introduced predator Mark C. Belk, Eric Billman, Josh Rasmussen, Karen Mock, Jerald B. Johnson

Predation – complex effects, experimental approaches

Transition matrix – a powerful tool Vital rates and matrix methods Combine matrix models with predation experiments Unravel ecological and evolutionary consequences of predation

Southern leatherside chub (Lepidomeda aliciae) serial mark-recapture experiment on two populations of southern leatherside chub – one that co-occurs with introduced brown trout and one without

Stage-structured model Serial mark-recapture, 2 locations, 3-4 years, 3-stages based on size and maturity Fecundity estimates based on independent samples Pre-breeding census model, s 0, survival of offspring from birth to first counting (1 year), applied to fecundity estimates

Three questions Are there detectable differences in mortality rate between brown trout and non-brown trout environments? What are population demographic consequences of brown trout predation? Which vital rates have the greatest impact on population growth and fitness?

Survival estimates No-predator – Salina Creek Predator – Lost Creek s 0 = s 0 =

JuvenilesYoung adults Old adults JuvenilesS1F2F3 Young adultsG1S2 Old adultsG1,2G2S F2F3 G1 G1,2 G2 S2 S3 Life cycle and transition matrix S1

JuvenilesYoung adultsOld adults Juveniles Young adults Old adults No-predator, Salina Creek JuvenilesYoung adultsOld adults Juveniles Young adults Old adults Predator, Lost Creek Transition matrices JuvenilesYoung adultsOld adults Juveniles S1F2F3 Young adults G1S2 Old adults G1,2G2S3

Demographics No predator, Salina Creek Predator, Lost Creek Population growth rate Net reproductive rate Generation time

Growth rates of individuals Billman et al. 2011, Eco. Fresh. Fish

Demographics

JuvenilesYoung adultsOld adults Juveniles Young adults Old adults No-predator, Salina Creek JuvenilesYoung adultsOld adults Juveniles Young adults Old adults Predator, Lost Creek Elasticity analysis JuvenilesYoung adultsOld adults Juveniles S1F2F3 Young adults G1S2 Old adults G1,2G2S3

Conclusions Are there detectable differences in mortality rate between brown trout and non-brown trout environments? – YES. Pattern is stage-specific and alternates What are population demographic consequences of brown trout predation? – change in λ, stable stage distribution, T – mainly through modification of growth rates (G) and the s 0 component of fecundity.

Conclusions Which vital rates have the greatest impact on population growth and fitness? – Early growth and fecundity contribute most to population growth and fitness

Application For fisheries, humans act as predator – Potential for strong ecological effects Introduced fish – Population demography as tool – e.g. effect of burbot on important fisheries species Native species conservation – Effect of introduced species – Effect of habitat degradation – Interacting effects