Complex sentence: In 1980 trade in over 13,000 monitors was declared, however in many remote places they are used as a food source and are killed because of their reputation for preying on domestic animals.
Split into simpler sentences: In 1980 trade in over 13,000 monitors was declared. Howeverm in many remote placesm they are used as a food source and are killed because of their reputation for preying on domestic animals.