Fenglin Bay is an ideal section for salmon spawning and breeding. If there were hydroelectric dams downstream, salmon would not be able to breed here. Only when the trees on the shore of Fenglin Bay have lost their leaves will the salmon migrate here. If you see many sea eagles and brown bears gathering in this bay, you will know that the salmon is migrating. Now there are a lot of migratory salmon in Fenglin Bay.
According to the above statement, which of the following can be obtained?
There is a hydroelectric dam downstream of Fenglin Bay