1)
Why does it mention birds and fish?
1.
Radak: Even beings not on the land with man, like birds that fly in the air, and fish that swim in water, man rules over them and traps them via strategies.
2)
Why does it say "Over Archos Yamim"?
1.
Radak: With man's intellect and strategies, he makes boats and crosses seas.
2.
Malbim: Refer to 8:8:3:2. In order to use fish, man must cross seas and endanger himself in seas and rivers before he reaches them. This shows that what is further from the creation of man, man has less use of it; it is merely an intermediary towards man.
