Why are killer whales hunting sea otters? What are the consequences of a decreased population of sea otters? Read to find out!
Sea Otters Profile
Sea otters usually live in the Northern Pacific Ocean and only in nearby coastal regions. Sea otters are unique animals with double fur coats and can live in environments as low as -4F. They can remain underwater for 30 to 90 seconds and live in shallow water. Their usual food sources include crabs, clams, mussels, sea urchins, and other creatures near the ocean floor. They crack open hard shells by floating on their back and using their belly to smash or using other hard rocks. Before they were being hunted for fur and food, the worldwide population was 300,000 but dropped to 150,000. The International Fur Seal Treaty of 1911 resulted from their hunting. There were many theories why their population decreased so rapidly, including hunting, oil spills, and killer whales.
Why are killer whales eating sea otters?
Killers whales in the past have never fed on sea otters until 1991 when the first case occurred. Killer whale's natural food sources are fish, squid, seals, birds, and even whales. However, when their food sources supply drops, they need to feed on animals that they rarely bother. When this theory came to light, no one believed it as killer whales even lived in the same territory as the otters. It is important to note that in Alaska, killer whales are the primary reason for their decreased population. However, after some searching, the truth appeared. They would swim upside down underneath the sea otter, and the whale would open its mouth and swallow the otter. Studies show that the original prey of killer whales became extinct in the 1950s and became harder to locate. Overexploitation, or overfishing, is a significant impact on the decrease of the whale’s food. If there were more fish and other animals, the killer whales would have plenty to eat. This was when the killer whales had to turn to sea otters. The sea otters are great food for the whales because they contain a massive amount of calories. The sea otters must take in a minimum amount of calories because of their habitat, lack of rubber, cellular respiration, fur, reproductive status, and cold water. Even though killer whales are a massive part of why the population of sea otters in certain areas decreases, there are many other effects. Those include competition, predation, parasites and diseases, unusual weather, and natural disaster. In 1977, Southern sea otters became endangered species.
What are the consequences of a decreased population of sea otters?
There are many consequences of a decreased population of sea otters. Keystone species such as sea otters were especially important to the specific environments and ecosystems, meaning their ecosystem would be unbalanced and collapse. Many studies and cases have happened in the past. Removal of sea otters would cause sea urchins to overgraze kelp and destroy the kelp forest, which is part of the sea otter food chain. Understanding the sea otter food chain is vital to comprehend why they are an important species. Sea otters are tertiary consumers in the kelp forest food web. An average amount of sea otters in the ecosystem will maintain each species' number, including sea urchins and the kelp. However, if sea otters' numbers decrease, the sea urchins will increase, resulting in a decrease in the kelp. Large fish are also part of the food web and increase because there is less competition for food. There is at least one keystone species in every ecosystem- for example, bees, starfish, sea otters, sharks, and more. Humans can not stop the process of killer whales eating the otters but can reduce overfishing and oil spills, contributing to their population.
Are there ways to help prevent the collapse of the food web?
There are multiple ways an average person can help maintain the ecosystem. The leading cause of the animal population decreasing is the over-harvesting of them. Many animals, including the Southern Sea Otter, fall under the umbrella term endangered species. It is vital to spread awareness of this situation. As years pass by and the kelp forest continues to decrease, the ocean animals will not survive, including sea urchins. The kelp provides shelter for many smaller animals and is essential to animal habitat. Creating more marine parks that are protected and increase the animal’s sustainability. Plastic and pollution have a significant impact on an animal's life span. In the future, I hope this problem can improve as in the long term, it can become a prominent issue.
Thank you for reading!
Written by: Amber Truong
Sources:
“Killer Whales Thinning Otter Population.” NPR.Org, choice.npr.org/index.html?origin=https://www.npr.org/templates/story/story.php?storyId=4665067#:%7E:text=Orcas%20were%20eating%20otters%20because,then%20to%20medium%2Dsized%20seals. Accessed 17 Apr. 2021.
News, Science. “Killer Whales Have Begun Preying On Sea Otters, Causing Disruption Of Coastal Ecosystems In Western Alaska.” ScienceDaily, 16 Oct. 1998, www.sciencedaily.com/releases/1998/10/981016075816.htm#:%7E:text=With%20seals%20and%20sea%20lions,studying%20the%20area’s%20marine%20ecosystems.
Magazine, Hakai. “We’ve Been Systematically Underestimating Sea Otters’ Historical Habitat.” Hakai Magazine, 10 Feb. 2020, www.hakaimagazine.com/news/weve-been-systematically-underestimating-sea-otters-historical-habitat.
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