Should people use animals for their purposes, if it means the endangerment of fauna?

In 2010 World Wide Fund for Nature in its report `a living planet` stated that animal population decreased by 28% from 1970 to 2007. Especially tropical species suffered greatly: their population has decreased over 37 years by 60%. Many animal species are disappearing from indirect human impact on their lives. Animal world, being a part of the natural environment, which emerges as an intrinsic link in the chain of ecological systems, an essential component in the cycle of matter and energy of nature, actively influence to functioning of natural communities. The fauna has great economic significance as a source of food, industrial, technical, medical raw materials and other assets. Some species have great cultural, scientific, aesthetic, educational and therapeutic value. The fact is that a person involuntarily takes away the natural habitat and their foraging areas from animals. Other reasons of decreasing number of animals are deforestation, plowing of the steppes, desert reclamation, drying wetlands, contamination of rivers with industrial waste, pollution of the seas and the atmosphere. These actions destroy animals as fast as with a gun or poison traps. So, how do you think, should people use animals for their purposes if it means the endangerment of fauna? How people relate to animals in your country? Have you noticed cruelty to animals? If you have, where and for what type of animal? Is there any benefit from animals?