Essay --

The numbers of marine mammals present in waters under the jurisdiction of the United States has fluctuated over the past century. Declines have been credited to various causes, which are a mix of anthropogenic and natural processes. One major cause of marine mammal decline is whaling. Even though this practice has been prohibited, the effects of commercial whaling in the United States can still be seen today. The main whale species affected included North Pacific right whales (Eubalaena japonica), bowhead whales (Balaena mysticetus), humpback whales (Megaptera novaeangliae), blue whales (Balaenoptera musculus), and gray whales (Eschrichtius robustus). Sei whales (Balaenoptera borealis) and sperm whales (Physeter macrocephalus) were exploited in an increased fashion after World War II (Springer et al., 2003). Whaling did not only affect whale populations, but it also affects populations of seals, sea lions, and sea otters. This is hypothesized to be the result of top-down forces from whaling, forcing great whales to shift their food sources to these smaller marine mammals. During the Second World War, whaling of great whales was at its peak. These whales were used for oils for lubricants, food, and other needs of the people of the United States. However, this heavy use of great whale stocks forced killer whales (Orcinus orca) to begin feeding on smaller marine mammals, such as seals, sea lions, and sea otters (Trites et al., 2006). It is also thought that declines in these smaller marine mammals is due to a decline in nutritional limits in their habitats, competition with fisheries, as well as changing climates. The North Atlantic right whale (Eubalaena glacialis) has had a slow recovery since the cessation of commercial... ...ws and acts such as the Marine Mammal Protection Act, the Endangered Species Act, Fur Seal Act, Fish and Wildlife Coordination Act, and the Coastal Management Act, have all helped to prevent the stocks of these important organisms from declining even further. Even though these have been enacted, the general public still needs to be educated and made aware of the population trends of these animals, as well as their importance to the tropic systems surrounding our coastlines. Many individuals do not realize, for instance, that Sea Otters are a keystone species in kelp bed habitats, and without them, kelp forests would dwindle in numbers and the health of those ecosystems would decline rapidly. Kelp forests provide habitat for over a thousand species of animals, many of which are important for fisheries and without those forests, fish abundance would fall as well.