INTERACTIONS BETWEEN LARVAL WHITE CRAPPIE AND GIZZARD SHAD - QUANTIFYING MECHANISMS IN SMALL PONDS

To test potential competitive interactions between larvae of white cra ppie Pomoxis annularis and of gizzard shad Dorosoma cepedianum, we add ed adult gizzard shad to eight of twelve 0.1-ha ponds that had been st ocked with adult white crappies. Larval white crappies and larval gizz ard shad appeared within 1 week of one another and larval white crappi e density did not differ between treatments. Zooplankton density decli ned similarly between treatments, and zooplankton species composition and size did not differ. Although larval white crappie and larval gizz ard shad had moderate diet overlap, prey selection by white crappie di d not differ between treatments. During April, more than 70% of larval gizzard shad had empty stomachs, compared with less than 20% of larva l white crappies. Age-0 gizzard shad recovery was extremely low (< 10 kg/ha) in five of eight ponds. Daily ring counts from otoliths indicat ed that late-spawned gizzard shad had higher growth rates than early-s pawned gizzard shad, whereas no such relationship existed for white cr appie. At a given size, age-0 white crappies weighted more in ponds wi th gizzard shad than in ponds without them. Contrary to our prediction s, gizzard shad did not negatively affect age-0 white crappies.