In a lake, the population of a particular fish species is about 1 million. Fish reproduce by 20% of the population each
Posted: Sat May 21, 2022 9:09 am
In a lake, the population of a particular fish species is about
1 million. Fish reproduce by 20% of the population each month,
regardless of the season. In addition, fish die naturally after
living for an average of 10 months. There are two separate
companies (for example, A and B) fishing with 5 boats on the edge
of this lake. According to current data, each boat catches 5000
fish per month. However, if the total number of boats caught in the
lake increases, the number of fish to be caught by each boat
decreases, as the boats will prevent each other from fishing. In
addition, if the fish population in the lake increases, the fish
caught per boat increases, and if the population decreases, the
fish caught per boat decreases. As companies earn money from
hunting, they want to buy new boats over time and enlarge their
boat fleet.
1. If you want to model this described system with 'System
Dynamics', which variables would you use? How would you classify
these variables as stock, flow and dummy variables?
2. Indicate the causal relationships in this system with arrows
and signs.
3. Show the causality loops in this system, at least 1 negative,
at least 1 positive, and at least 4 in total, and interpret the
loops.
4. Draw the stock-flow model of this system.
5. Write down the equations (as much as possible) of the model
you have drawn above.
6. Assuming the number of boats of the companies and the number
of fish caught by each of the boats are constant, is the system in
equilibrium? If not, in what direction is the system changing?
1 million. Fish reproduce by 20% of the population each month,
regardless of the season. In addition, fish die naturally after
living for an average of 10 months. There are two separate
companies (for example, A and B) fishing with 5 boats on the edge
of this lake. According to current data, each boat catches 5000
fish per month. However, if the total number of boats caught in the
lake increases, the number of fish to be caught by each boat
decreases, as the boats will prevent each other from fishing. In
addition, if the fish population in the lake increases, the fish
caught per boat increases, and if the population decreases, the
fish caught per boat decreases. As companies earn money from
hunting, they want to buy new boats over time and enlarge their
boat fleet.
1. If you want to model this described system with 'System
Dynamics', which variables would you use? How would you classify
these variables as stock, flow and dummy variables?
2. Indicate the causal relationships in this system with arrows
and signs.
3. Show the causality loops in this system, at least 1 negative,
at least 1 positive, and at least 4 in total, and interpret the
loops.
4. Draw the stock-flow model of this system.
5. Write down the equations (as much as possible) of the model
you have drawn above.
6. Assuming the number of boats of the companies and the number
of fish caught by each of the boats are constant, is the system in
equilibrium? If not, in what direction is the system changing?