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AP Environmental Science Unit 5 FRQ Practice

Practice a College Board-style free response question on Land & Water Use. Write your response, then reveal the model answer to see exactly what earns each point.

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Free Response Question · Unit 5 · Overfishing & the Tragedy of the Commons

An open-access coastal fishery has no catch limits, no licensing requirements, and no enforced boundaries — any fisher can fish there freely. Researchers tracked the total cod population and the number of fishing boats operating in the fishery over a 20-year period.

YearNumber of fishing boatsCod population (metric tons)
04050,000
59038,000
1016021,000
152108,000
202202,500
A
Using the data, describe the relationship between the number of fishing boats and the cod population over the 20-year period, and identify the ecological/economic concept that explains why this fishery was vulnerable to this outcome.

✓ Model answer (earns the point)

As the number of fishing boats increased from 40 to 220, the cod population declined sharply from 50,000 to 2,500 metric tons — an inverse relationship. This fishery was vulnerable because it is a tragedy of the commons: as an open-access, unregulated resource with no catch limits or licensing, individual fishers had an economic incentive to maximize their own catch, since restraint by one fisher would simply allow others to catch the fish instead, with no individual benefit to conserving the shared stock.

Why it scores: Describes the inverse relationship using specific data values AND names the specific concept (tragedy of the commons) with the correct mechanism (individual incentive vs. collective cost) — not just "overfishing happened" without the underlying economic logic.
B
Explain one ecological consequence of the cod population collapse for the broader marine food web in this region.

✓ Model answer (earns the point)

One likely consequence is a population boom in the cod's prey species (such as smaller fish or invertebrates the cod normally eat), since removing cod as a predator reduces the predation pressure that previously kept those prey populations in check. This could in turn deplete the prey's own food source, cascading further through the food web.

Why it scores: Identifies a specific, logical ecological consequence (prey population increase from reduced predation) tied directly to the cod's role in the food web — not a vague statement like "the ecosystem will be affected."
C
Propose one specific policy the government could implement to prevent further collapse of the fishery, and explain how it would address the underlying cause identified in Part A.

✓ Model answer (earns the point)

The government could implement individual transferable quotas (catch limits) that cap the total amount of cod each licensed fisher is allowed to catch per season. This directly addresses the tragedy of the commons by converting the previously open-access resource into a regulated one — each fisher now has a defined, enforceable share, removing the incentive to race to catch as much as possible before others do. (Other valid answers: establishing a licensing system limiting the number of boats, or creating a marine protected area where no fishing is allowed to let the population recover.)

Why it scores: Names a specific policy AND explicitly connects it back to the Part A mechanism (removing the individual incentive to overexploit a shared resource) — not just naming a policy without the cause-and-effect explanation.

How to score points on AP Environmental Science FRQs