Guys :

A few points and words of caution. First I am not sure anyone knows the answer. I doubt they do and would be wary of any easy answer. Most research on crappie has been conducted on large reservoirs and not much on ponds. These are some reasons listed for inconsistent spawn. I have not seen info stating they skip a year, only that the numbers vary wildly as one author puts it " a genus notorious for variable recruitment".

spawning stock size as a predictor of recruitment

larval density

environmental variables to predict recruitment including water level,temprature, turbidity, substratum, and wind

daily water elevation to determine the impact of hydrology on recruitment.

chlorophyll best explained the variation in larval density and age-2 recruits

spawning stock and chlorophyll explained 63�64% of the variation in larval density

strong year-classes being produced every 2 to 5 years

crappie recruitment is quasi-cyclic due to random fluctuations in the environmental variables and density dependent mechanisms

exploitation i.e., condition, total mortality , length and age distribution

Stocking predators to reduce the abundance of slowly growing populations of crappies Willis et al. (1984) but caution and consideration must be given to the effects of such biomanipulation on all trophic levels

These are the factors most listed but most studies warn that to much is unknown and no sure answer exists todate. I hope this helps.