-8- 



where FRM is the coefficient for daily food requirement for maintenance, and FRG 

 is the coefficient of food requirement for growth. Both coefficients are expressed 

 as a fraction of the biomass or growth in biomass, and are input parameters. 



Amount Consumed of Each Prey by Each Predator (CPN ) 



There are two sets of inputs that determine the amount of consumption of a 

 prey group by a predator. Firstly, a table of the percentage food composition of 

 each predator (derived from stomach analyses modified to include the juvenile 

 feeding) is input, CF , , and together with the food requirement for each predator, 

 (FOOD ) , the actual food required by each predator group from each prey group, 

 (CPN ), is determined. These values are summed over each prey group to give 



IN J K 



the total amount of food required from each group, (CC , ) . 



Total food requirement (CC.. ,) is compared with the allowable consumption of 



IN I K 



each prey group's biomass, (AC,). The allowable consumption is the second set 

 of input values, where the allowable consumption is input as a percentage of 

 that prey group's biomass, (AP, ) , and the allowable consumption, (AC,), is 

 computed from the current biomass of that group. 



At this stage, then, the food required by each predator group of each prey 

 group and the allowable consumption for each prey group are known. These values 

 are now used to modify the input food composition table to reflect the influence 

 of prey abundance on feeding. The ratio of allowable to required food consumption 

 of each prey group is formed, (FCOC, ) , and the adjusted percentage food composition 

 of the predator's diet is made a function of this ratio and the input percentage 

 food composition: 



1 + Ae"^ 

 FCN., , = CF. •'- ' ^^ 



N.k N,k , ^ ^^-B^VFCOC^ 



