20 And God said, “Let the water teem with living creatures, and let birds fly above the earth across the vault of the sky.” 21 So God created the great creatures of the sea and every living thing with which the water teems and that moves about in it, according to their kinds, and every winged bird according to its kind. And God saw that it was good. 22 God blessed them and said, “Be fruitful and increase in number and fill the water in the seas, and let the birds increase on the earth.” 23 And there was evening, and there was morning—the fifth day. Genesis 1:20-23
The oceans and air is filled with fish and birds. There are too many to count. No one even tries. They exist within their own ecosystem. Humans are a part of that ecosystem when we hunt and fish for food. What’s the reason God told them to multiply? To fill the earth. He was preparing the way for mankind. Of course we would eat the plants he prepared on a previous day, but he was beginning to provide the meat for humans. There would be so much that we couldn’t handle it all, and it gets replenished as birds and fish multiply.
I think we would be amazed if we went deep sea diving and had the ability to see clearly for miles. We’d see that, to quote the famous song, there are a lot of fish in the sea. And that’s one tiny part of one extremely large body of water.
Once again I am astounded at the depths God took to provide for his future creation.