Barrowman, Nicolas J.; Myers, Ransom A.; Hilborn, Ray; Field, Chris A. 2003. The variability among populations of coho salmon in the maximum reproductive rate and depensation. Ecological Applications. Vol: 13(3). Pages 784-793. (Abstract) (Online version)
Estimating parameters for populationâ€dynamics models is a critical component in assessing extinction probabilities of populations. For many individual populations, key parameters will be poorly defined, and metaâ€analysis would provide a basis for estimating the parameters. Here, we introduce metaâ€analytical techniques to estimate the maximum reproductive rate, carrying capacity, and depensation in coho salmon on the west coast of North America. We used both nonlinear mixedâ€effects models and Bayesian techniques to estimate several populationâ€dynamics models, including the Bevertonâ€Holt and hockeyâ€stick models, for 14 spawnerâ€“recruitment time series. The Bevertonâ€Holt and hockeyâ€stick mixedâ€effects models yielded equivalent fits to the data but gave very different estimates of Î± (the maximum rate at which female spawners can produce female smolts at low population sizes). The mean Î± for the Bevertonâ€Holt mixedâ€effect model was 71.5 (1 se = 1.2) female smolts per spawning female, whereas the hockeyâ€stick estimate was 53.0 (1 se = 1.14). We found little evidence for a general effect of depensation in coho salmon, unless fewer than one female per kilometer of river returned to spawn.