The hybrid crappie can reproduce. The success of their reproduction and how viable their offspring are is what's at question. Triploid crappies if they ever become available would be interesting...
Looks like the hybrid would be an improvement though....
"Hybrid Crappie
The Hybrid Crappie (Black/White Cross) are finally available as an option for stocking crappie in smaller lakes and ponds. Traditionally crappie have not been recommended for stocking in less than 10-15 surface acres due to their potential to overpopulate. The spawning potential of hybrid crappie is greatly reduced compared to that of their white and black crappie counterparts, so they are a better option for small waters. Suggested stocking rate is 100-150 per surface acre. Ideal forage for crappie are minnows and threadfin shad." OvertonFisheries 
