Trout and other fish were once caught commercially in Canada’s Great Lakes.
But canals constructed between the lakes before 1900 let a predator, the lamprey, get into the lakes.
The lamprey feeds on trout, so the fishing industry collapsed.
Fig. 5.1 displays fish catches across 65 years.
(a(i))[1]
State in which five year period the greatest mass of fish was caught.
(a(ii))[1]
State in which five year period the smallest mass of fish was caught.
(a(iii))[2]
Calculate the decrease in fish catches between 1900 and 1964. Show your working.
(b)[1]
Suggest whether the barriers were effective. Explain why.
(c)[3]
Suggest three human activities that could make trout numbers fall.
(d)[2]
Describe two methods used to conserve endangered species.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “largest catch: 1905-1909” …