104


 W = 4.76 (0.00405 00.11766x ) (24)



 where W is wet weight and x is length.
 w
 An "area of attraction" of the pond for fish was

 estimated by drawing a line on a scaled map halfway between

 Mud Lake Pond and the nearest neighboring ponds (or

 ditches). The area of attraction of a pond is defined as

 that area of the marsh from which fish are more likely to

 move (have a higher probability of moving) into that pond

 than into any other pond to escape adverse conditions in

 the marsh during the dry season.

 Food consumption by gar from November 25 to June 12

 was calculated as the sum of growth, respiration, and

 unassimilated food. Growth of gar during the study period

 was calculated using the same equations used to calculate

 growth in Gambusia. An estimate of initial (November 26)

 weight was obtained by extrapolating backwards from known

 values on March 31 and June 12. Winberg's (1956) standard

 equation was used to estimate gar respiration. The

 standard metabolic rate was .doubled to allow for a low

 level of activity by the gar, which was assumed to prevail

 under crowded conditions such as those in the pond during

 low water. The standard assimilation ratio for fish, 0.8,

 was used in these calculations. The simple energy circuit

model and equations used to determine food consumption by

gar are given in Figure 19. Calculated food consumption