The fish change their diet to one of declining caloric density as they grow older.
These changes are captured by FCC1, FCC2, and FCC3:
FCC1 ¼ IF G SIZE < 30
ð
ÞAND G SIZE ! 0
ð
ÞTHEN 500 ELSE FCC2 ð36:3Þ
FCC2 ¼ IF G SIZE ! 30
ð
ÞAND G SIZE < 100
ð
Þ THEN 1000 ELSE FCC3
ð36:4Þ
FCC3 ¼ IF G SIZE ! 100 THEN 430 ELSE 0
ð36:5Þ
Actual ingestion is determined in the plant module (shown below) but the
desired ingestion, DESIRED INGEST, is a function of the caloric density,
the average eating rate, BWPD, a factor for comparing triploid eating rates to the
natural carp eating rate, PLOIDY, the grams size, G SIZE, and a voraciousness
factors TC and TC1 which depend on the water temperature:
DESIRED INGEST ¼ 7 Ã BWPD Ã G SIZE Ã TC Ã PLOIDY Ã FCC1 ð36:6Þ
BWPD ¼ IF G SIZE < 15000 THEN 0:52 ELSE :21
ð36:7Þ
Fig. 36.3
314
36 The Grass Carp