The economy around Lake Paqua depends on fishing of the lake's landlocked salmon population. In recent years, scarcity of food for salmon there has caused a decline in both the number and the size of the adult salmon in the lake. As a result, the region's revenues from salmon fishing have declined significantly. To remedy this situation, officials plan to introduce shrimp, which can serve as a food source for adult salmon, into Lake Paqua.Which of the following, if true, most seriously calls into question the plan's chances for success?
【选项】Tourists coming to fish for sport generate more income for residents of the Lake Paqua region than does commercial fishing.