When we read in Genesis Ch.7 that Noah was to take with him seven of all clean animals, of course taking both male and female/ and two of all unclean animals, also male and female.
Scripture then continues in verse 3 saying
also seven each of birds of the air, both male and female, to keep the
species alive on the face of all the earth. (NKJV)
As we know, birds lay eggs that can either be eaten as such or hatched for a supply of poultry. Also, nobody is taking into account the fish that would be available. The bible clearly states later in verses 17-24 that he destroyed all living thing that breathes air and lives on dry land, never speaking of things that swim in the waters below.
The simple answer may be that the carnivores ate fish
When I think even deeper into the situation, animals such as small rodents would procreate rapidly and maybe were also used as a protein source for the animals. Bugs may have been another source of protein for some.