84
5. Impact of Fishing Pressure on Mean Length of Fish
o
MED&LONG FISHING MORTALITY
TOTAL SHORT POP
TOTAL MED POP
TOTAL LONG POP
TOTAL POP
FIGURE 5.8
The relative share of short fishes in our population increases through
time. The curves in Figure 5.10 fluctuate in a similar way from run to run
because we used a seed to specify the various random numbers that define
the birth rates. These fluctuations make it a bit difficult to compare the
trends in the model. To "filter" out some of the year-by-year variation due
to this randomness, you can make use of STELLA's built-in smoothing func1: TOTALPOP
1: 9500.00 . -2: TOTALPOP
- - - - -,-3: TOTALPOP
- - - - ---,4: TOTALPOP
- - - - -
5: TOTALPOP
..,.-- - - - - - --,
2
1: 5000 .00
5
....-----....-----...
40.00
60.00
80.00
Years
20.00
1:
500.00 0.00
FIGURE 5.9