And God blessed them: this is the first time in the creation story that God is said to have done this. Further blessings will be given to man (verse 28), and then to the seventh day (2.3).
Blessed is the most common word in the Old Testament for God doing something favorable to someone or something. The problem for the interpreter is to know what is the nature of a blessing given to sea animals and birds. Most interpreters are agreed that God’s blessing in the creation story is the gift of reproduction. Accordingly the blessing is contained in the command “Be fruitful and multiply…,” which occurs again in verse 28 in regard to human beings, and in 8.17 and 9.1 concerning Noah, his sons, and the animals after the flood. The command means “to reproduce, have young, increase in numbers.” The idea may be expressed in this context, for example, as “God acted with great favor toward them by saying ‘May you become numerous,’ ” “… ‘Have many offspring,’ ” “… ‘May you reproduce in large numbers.’ ” Alternative expressions for the sense of blessed are “God was good to the birds and animals and said to them,” or idiomatically, “God showed his good heart to them when he said.”
And fill the waters in the seas: the command continues in a way that is addressed to the water creatures and applies to them. Translators should avoid a term for fill that may suggest “filling to overflowing.” Fill is a term that can have any one of several meanings, depending on its context, and in some languages it may be better to say “May there be great numbers of you…” or “You should increase until you are very many.”
And let birds multiply on the earth: this command, omitting the expression Be fruitful, applies to the birds, but the command is in the third person in Hebrew, as Revised Standard Version shows. Good News Translation expresses both the commands of blessing in this verse as indirect quotations “He … told the creatures that live in the water to reproduce and to fill the sea, and he told the birds to increase in number.” Good News Translation has not included the words on the earth, since the contrast with the waters in the seas is clearly shown with just the term birds. However, it is also possible to say, for example, “and let the birds increase in number on the land.”
In many languages the most natural way to express the commands of blessing will be to use direct quotations, addressing the two groups of creatures in turn. For example, one translation says “Fish, you must have many children, so that the sea becomes filled. And birds, you must have many children too, so that you become numerous.”
Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Genesis. (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .