Decreased demand.
The supply of goods and services corresponds to the demand for goods and services. Thus, production and supply depend on demand. This is intuitive, a good will only be sold if there is someone who buys it.
In the issue presented, there is a decrease in the birth rate of the city. This will have a social and economic reflection. There will be less work force and fewer people to buy. Consequently, there will be a lower demand for goods and services, which will be perceived by store owners.