Thousands of dolphins and small whales throughout the world continue to be hunted for food, oil, fertilizer and other products.
What may turn out to pose the greatest threat to dolphins (and other marine animals for that matter) is contamination of the marine environment. Pesticides, PCBs, heavy metals, plastic particles, radioisotopes and other industrial wastes are released into the oceans, bays and rivers in unknown amounts daily. Many of these pollutants do not break down in the environment, or take a very long time to do so. For species with a wide geographical range, environmental degradation may not be as critical, but those species that have a limited or localized distribution may become quite vulnerable. The populations of several of the river dolphins have been drastically reduced by a combination of man-made factors including pollution, damming, increases in boat traffic and shoreline development. In addition, many dolphin deaths have been attributed to swallowing man-made objects including balls, nets and pieces of plastic.