Chicken breeders could be referred to as chicken wranglers; sellers of chicken meat for food would be meat marketers.
A person who sells fowls, such as ducks or turkeys, is commonly referred to as a poultry vendor or a poultry seller. The term "poulterer" can also be used to describe someone who specifically sells poultry for consumption. Additionally, in a more general sense, they could be called a poultry farmer or a poultry producer, depending on whether they raise the birds themselves.
docter
poultryman
An author is a person who writes and sells books.
The person who sells drink is known as sellsmen
baker
A bookie. Droll. You could call that person a bookseller or shopkeeper.
You call a person who sells flowers a (Florist)
A person who sells ship supplies is called a chandler
That person would be called a traitor.
A person who sells jewels is called a jeweler.
fishmonger