Complex sentence: As the bears became more desperate for food and more aggressive, more of them were encountered in camps an in the next several years, over 100 grizzly bears had to be euthanized and the park bear population was on the brink of extinction.
Split into simpler sentences: As the bears became more desperate for food and more aggressive, more of them were encountered in camps and had to be destroyed. In the next several years, over 100 grizzly bears had to be put down, and the park bear population was on the brink of extinction.