Overfishing causes the yellow perch population in the food web in the diagram to decrease.
Otter
Terrapin
Osprey
Blue
crab
Algae
Snail
Yellow
perch
Shrimp
Cord grass
Which population is most likely to decrease as a result?

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it

What's the question?

Where is the data? ? and graph