“economy” and “trades”

But the daytime economy is already heavily exploited by other creatures such as birds. Given that there is a living to be made at night, and given that alternative daytime trades are thoroughly occupied, natural selection has favoured bats that make a go of the night-hunting trade.

1. I am pretty confused by “economy” and “trades” here, as the original meaning of them are not related with the meaning in the sentences.
2. What does “make a go” mean? Can “go” be a noun?

Thanks a lot.