The graph to the right shows the rate of salmon entering a fish hatchery during a $60$ minute period. 

1. A gate fell a couple of times during the time interval disrupting the flow of the salmon. About what time did this occur?

   Hint (a):

   Where does the graph have a maximum followed by a steep decrease?

2. What does the shaded area represent?

   Hint (b):

   Multiply the units on the axes.