Instructions - Spotted Fish Model

The spotted fish applet lets you track the change in spot size in a closed pond with a constant number of predators. Start the model by pressing the run button. The graphs of the results will automatically update while the model runs. The model will run until either the population of fish in the pond exceeds 1000, the time exceeds 1000, or there are no fish left in the pond.

To stop a model currently running, press the stop button.

You can change the input parameters by changing the values in the appropriate box:

• # of fish: Number of spotted fish initially in the pond.
• # of predators: Number of pickerel in the pond.
• time to digest: The amount of time it takes for a predator to become hungry again after eating.
• gestation period: The gestation time for spotted fish
• adult age: The adult age of a spotted fish
• old age: The lifespan of the spotted fish
• hunting time scale: The time it takes for a hungry predator to spot and catch prey, based on a spotted fish with a spot size of 0.1
• mating time scale: The typical time between mating for two fish in the pond, based on a fish with the mean spot size of the population.
• mutation factor: A factor which controls how much the offspring's spot size can deviate from its parents.