Endangered Blue Whales by Chris Reiter

Author:Chris Reiter
Language: eng
Format: epub
Publisher: Enslow Publishing, LLC

Chemical Threats

Whalers are not the only threat to whales. Many chemical products made by humans have been found to be extremely harmful to marine life, and the substances are still finding their way into ocean waters. Some of the most harmful chemicals are compounds known as organohalogens, which are commonly found in pesticides, insecticides, herbicides, and fungicides. While many organohalogens are no longer produced, they are still being released into the environment when disposed of improperly.

One type of organohalogen, polychlorinated biphenyl (PCB), is a fairly common pollutant. When whales feed on small animals with PCBs in their tissues, the chemical accumulates in the whales’ flesh in high levels. That accumulation can lead to serious health problems for whales by affecting their ability to have offspring and weakening their immune systems. Even though PCBs are no longer produced, many nations still use existing supplies.

Fishing Threats

Many cetaceans also lose their lives each year in accidental killings when they get caught in fishing nets. Dolphins, for example, get caught in nets intended to catch tuna because tuna often swim beneath dolphins and follow them to sources of food.

Even greater numbers of cetaceans are believed to have drowned in drift nets, which are now banned worldwide by a United Nations declaration.5 Drift nets are nearly invisible and highly flexible nets that trap any marine animal larger than the holes in the nets’ mesh. Before being banned, drift nets were being used to catch more fish than any other method of fishing. These nets were secured on either end by floats and sometimes extended up to 60 miles (96 kilometers). They were cast out at night when the fish could not see them and collected the following morning. In addition to catching nontarget fish, which were simply thrown away, drift nets accidentally killed hundreds of thousands of marine mammals each year, as well as large numbers of seabirds and sea turtles.6 Unfortunately, despite the ban, illegal fleets still use drift nets on the high seas.

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