Why are fish in the ocean an example of a resource that suffers from the tragedy of the commons but cattle grazing in a farmer's pasture do not suffer from the tragedy of the commons?

What will be an ideal response?

Fish in the ocean are a common resource because they are rival, so that one person catching a fish prevents others from catching the same fish, and they are nonexcludable, so that no one can be prevented from fishing. As a result, over-fishing is likely to occur. But cattle grazing in a farmer's pasture are not a common resource. The cattle are rival, so that one person butchering a steer prevents others from butchering the same steer, but the cattle are excludable, so that no one can butcher a steer unless the cattle's owner is compensated. As a result, the owner has the incentive to conserve the resource, that is, the owner has the incentive to insure that the cattle are not overused.