Hansen et al. (1998) modeled recruitment variation of age-0 Walleye (Sander vitreus) in Escanaba Lake (Wisconsin) to determine factors regulating their abundance. Specifically, they examined the abundance of age-5 and older Walleye (spawning population), variation in May water temperatures, and abundance of 152.4 mm total length and longer Yellow Perch (Perca flavescens) on the abundance of age-0 Walleye. These data are available in this CSV file (these data are also available in
Load these data into R to answer the following questions. [Note that this is an extension of this recruitment exercise.]
- Fit the Ricker stock-recruitment function with a multiplicative error structure to age-5 and older and age-0 abundance data. [Note that this would have been completed in this recruitment exercise.]
- Determine if adding the variation in May water temperatures or the abundance of Yellow Perch significantly improves the predictive power of the model.
- If either of these two variables improved the predictive power of the model then answer the following.
- Express the best model by replacing parameters with their estimated values.
- Specifically describe the effect of the other variables on the recruitment of age-0 Walleye.
- Do you feel that this model provides a clear explanation for the variability in recruitment of age-0 Walleye in Escanaba Lake? Explain.
from Derek H. Ogle , created 02-Oct-15, updated 02-Oct-15, Comments/Suggestions.