Post-stocking survival of 0+ year pike in ponds as a function of water transparency, habitat complexity, prey availability and size heterogeneity

Survival of 0+ year pike Esox lucius (20–31 mm L _T) was evaluated over the first week following stocking in ponds (16 m²) depending on water transparencies (low and high), habitat complexity (low and high) and food availability (zooplankton). A multiple regression analysis showed that survival, essentially as a result of cannibalism, decreased with increasing size heterogeneity of pike, and the decrease was steeper when no food was available. Survival was equal in clear water and water containing copper chlorophyllin (chlorophyll), and slightly higher in complex than in simple habitats, but only when alternative prey availability was low. Conversely, growth in water containing chlorophyll was slightly faster than in clear water. This suggests that initial size heterogeneity is the prevailing factor controlling mortality when stocking 0+ year pike almost irrespective of the stocking environment.