301

conditions tested. In Model II (Figure 74) maximum fish

biomass approaches 1.4 g/sq-m under primitive conditions

but falls to 0.01 g/sq-m under most drained conditions.

Fish density, which exceeds 3 g/sq-m under primitive

conditions in Model II, reaches only 1.5 g/sq-m in Model I.

Fish density drops to 0.03 g/sq-m under extreme drainage

conditions in Model I but to only 0.44 g/sq-m under extreme

drainage conditions in Model II. Values for other

parameters show similar response to the different

conditions of drainage, with responses being more extreme

in Model II than in Model I.

 In Table 34 is a comparison of the annual number of

fledglings produced under different drainage conditions as

simulated by the two models; Model I with fish stock at the

beginning of the preceding wet season unimportant, and

Model II with initial fish stock a major factor. No more

young are produced under primitive conditions than under

present conditions in Model I, but the number of birds

produced under primitive conditions is slightly more than

double that produced under present conditions in Model II.

Both models slightly underestimate the number of

fledglings actually produced under present conditions,

6,600 at Corkscrew in 1974-75 (J. Hansen, pers. comm.).

The number of young produced under primitive conditions by

the models could, with reservations be compared to the

actual number produced at Corkscrew in 1960-61, when the

area was only slightly drained. Kahl (1963) reported