Lake Victoria, shown in the population map above, is the largest lake in Africa and is home to fish called cichlids (pronounced SIK-lids). In the 1950s, a new
fish, the Nile Perch, was introduced into Lake Victoria. This map shows the
change in the cichlid population since the Nile Perch was introduced.

Use the map above to answer the questions below.

1. Using a Key In which year was the number of cichlids the greatest?

2. Using a Key How many years did it take for the cichlid population to decrease
by 50 percent?

3. Inferring Relationships Which fish in Lake Victoria do you think is higher on
the food chain
the cichlid or the Nile Perch? Explain your answer.

4. Identifying Trends Based on the rate of decrease of cichlids shown on the map,
what do you think will happen to the cichlid population by 2050? Explain your
answer.