Here is the complete statement:
The black footed ferret specie can be saved by the ENDANGERED SPECIES ACT. The US FISH AND WILDLIFE SERVICES will manage the Act.
EXPLANATION:
An endangered specie refers to an animal or plant species, whose population has become very low and is in danger of becoming extinct in the nearest future. In the United States of America, such plants and animals are usually managed by the Us Fish and Wildlife services. This is a federal agency that is responsible for the management of different forms of wildlife, fish and natural habitats within the US.
The Endangered Specie Act is a US law that makes provisions for the management of both plants and species, which are deem to be on the verge of becoming extinct. The law makes provisions for the conservation of endangered living organisms and their natural habitats. The endangered specie Act prohibits the hunting or killing of endangered species; acting contrary to this law usually carry severe penalties.
Population decreases by 15.
Birth rate means more population (positive), death rate means less population (negative), immigration means more (positive), and emigration means less (negative). So, just add and subtract the appropriate numbers:

Negative 15 people means that the population decreases by 15.
Answer:
The control sample is those sample that is used in the experiment to guarantee that the examination of the experiment is done properly and the results that are obtained are reliable.
These samples are an important component of the quality assurance that is used in order to prevent any inaccuracy of the laboratory results.