Why has the U. S. Fish and Wildlife Service said that no more captive-bred wolves will be used to bolster the population of red wolves in North Carolina?

This is to stop their killings as they are already an endangered specie.

Explanation:

the decision to either end the program or modify it has been expected. The US fish and wildlife service has  it will continue to manage the program and it would lift restrictions on killing stray wolves that stray from their territory. There is a fear of the specie vanishing in less than a decade and currently landowners need permission before they can kill any of these animals that wander into their properties. Even though these landowners have referred to these animals a nuisance on their properties, the wildlife service in a report has said it would continue to recognize the species.