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~r .. Bullfrog Tadpoles. Tadpoles are often associated with poor production in hatchery ponds, however, until recently, there has been little evidence to suspect t~em of direct predation. Tadpoles have been traditionally conr,idered microphagous feeders. Petra.nka and Kennedy (1999) recently reported that many anuran larvae are macrophagous predators, feeding on a wide variety of macroinvertebrates. They also presented data showing that tadpole larvae can be cannibalistic and feed on other anuran species. There are few reports of tadpoles feeding directly on fish. A veterinarian reported on the Internet that high densities of tadpoles had actually killed adult goldfish (www.fishdoc.co.uk). Boyd (1975) reported that bullfrogs interfered with fish production, but showed no evidence of direct predation. Another paper reported toad tadpoles had consumed on average 17 white catfish larvae per day (Nguenga et al. 2000). The catfish were found to be most vulnerable during the first 6 days after hatching. Underwater monitoring, confirmed by snorkeling, indicated that tadpole densities were inversely proportionate to depth. Densities ranged from 0.9 tadpoles/m2 (0 to 9.26, n=286) in the deeper (2 to 3 m) razorback sucker spawning site, to 2.8 tadpoles/m2 (0.45 to 5.22, n=48) at the control sites (non-spawning, 1 m depth), to a high of3.7 tadpoles/m2 (0 to 17.49, n=222) along shore (bonytail spawning site, 50 em depth) (Table 1). Based on control densities (2.8 tadpoles/m2), it is estimated that CHLP could support nearly 57,500 animals. We feel this is conservative, since densities in cattail stands is much higher and not include in these estimates. Based on predation rates (17 white catfish larvae/day) reported by Nguenga et al. (2000) it is conceivable that tadpoles could consume nearly 1 million fish larvae per day in CHLP. Table 1. Average densities of bullfrog tadpoles (TP), razorback suckers (RZB), and bonytail (BT) determined using video footage taken at razorback sucker and bonytail spawning sites and control sites at Cibola High Levee Pond. Location RZB site BT site Control Date 2/19 to 4/1/2003 4/2 to 4/16/2003 4/7 to 4/8/2003 TP 1m2 0.89 3.66 2.84 RZB/m2 4.26 0.23 0.00 BT/m2 0.00 17.44 0.00 RZB/min BT/min N 10.64 0.19 286 0.38 22.33 222 0.00 0.73 48 Based on this information, we initiated laboratory tests to determine if bullfrog tadpoles and crayfish would eat sucker eggs and larvae. These tests will be further refined next year. 11