9. Model output animation of response to reduced food availability using the "maximize expected maturity" (EM) movement objective.

This animation is a plan view (down from above) of the model stream. Habitat cells are shaded by depth- brighter cells are deeper. Flow is from right to left through this riffle-pool-riffle sequence. The blue line segments are individual adult trout, and segment length represents trout size (except for graphics resolution errors). Fish in each cell are displayed from top to bottom in order of decreasing length.

The simulation is initialized with five trout of nonuniform size. Five initial time steps occur with normal concentrations of drift food, then drift concentration is decreased to 1/3 of normal for the remaining 15 time steps. The animation automatically replays when finished.

In the EM simulation, trout immediately respond to the change in food availability by moving to a cell with higher food intake. Their initial cells provide high survival probabilities and sufficient food to minimize starvation risk. When food availability is reduced, starvation risk dominates EM so trout move to cells where food intake is higher to reduce starvation risk. On the last time step in the simulation, the smallest trout moves again to a cell with even higher intake and higher risks as its energy reserves decline.