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For over a month, plastic waste containing shopping bags and food packaging containers put the life of a green sea turtle at risk. While the turtle gradually excreted the foreign objects, it was unable to eat for a month. The incident put a spotlight once again on the seriousness of plastic waste in the ocean.
The green sea turtle was brought to the Kaiyukan Aquarium (Minato Ward, Osaka City) after it was rescued last November. It had strayed into a fixed net in Kochi Prefecture’s Tosashimizu City.
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A Month of Not Feeding
Last year on November 30, the green sea turtle, rescued by Kaiyukan’s research center the Iburi Center in Tosashimizu City, Kochi Prefecture, arrived at the Kaiyukan Aquarium in Osaka. The young turtle had a body with a carapace length of 44 cm, with no external wounds and nothing unusual seen in its swimming abilities. However, even 2 weeks after arriving at the aquarium, the turtle showed absolutely no signs of feeding.
In the beginning it was thought that the turtle was still unable to adapt to the environment because it sometimes swam away when it saw signs of people. But on December 19, something unusual was found. Plastic waste: plastic shopping bags, food packaging containers, and pieces of agricultural sheeting were found at the bottom of the water tank. They had apparently been stuck in the turtle’s digestive tract, before finally being excreted.
The discharge of plastic waste continued on until the beginning of the New Year. And for a month, the sea turtle ate no food.
Although after some time the turtle started eating in small amounts, the aquarium’s fish keeper, Itsuki Kiyatake (28) was still worried and consulted a veterinarian. In January 2021 an x-ray was conducted on the turtle, revealing a shadow in its intestine. The turtle was monitored while undergoing treatment such as injections to stimulate intestinal activity. The veterinarian was able to identify the shadow gradually growing smaller, and in May of this year the foreign object had finally disappeared.
Showing relief, Mr. Kiyatake explained, “It must have been hard on the turtle because it was unable to defecate sea acorn shells and seaweed due to the foreign objects trapped in its digestive tract. Now it is feeding steadily. Luckily, the situation did not become more serious.”
Mistaking Waste for Seaweed
The sea turtles depend on a diet of seaweed and jellyfish. Unfortunately, plastic bags that float on the ocean surface are easily mistaken for shredded seaweed or jellyfish, so sea turtles eat them, too.
Accidently swallowed plastic waste remains in the digestive tract for an extended time. It may damage internal organs or lead to emaciation due to the sea turtle being unable to feed, and threatens serious damage to the health of sea turtles.
Yoshimasa Matsuzawa, director of Shikoku Aquarium and an expert on the ecology of sea turtles, points out: “Green sea turtles live in coastal areas because they mainly feed on seaweed. Therefore, they are especially susceptible to human activities.”
Furthermore, the problem of sea turtles damaged by marine plastic waste is becoming a global issue. One study by a British university revealed that plastic waste was detected by researchers in the internal organs of all 102 dead sea turtles collected from the Pacific, Atlantic and Mediterranean oceans.
Although the most common direct cause of death is injury sustained from getting caught in fishing nets, Matsuzawa explained: “Health damage caused by plastic waste is becoming a serious problem.” He then went on to plead with the public to change wasteful ways:
“There have been other cases where rescued sea turtles have discharged plastic waste, but with the recovery process of a sea turtle at a popular aquarium like Kaiyukan becoming widely known, it may be a good opportunity to motivate people to reduce plastic waste.”
Currently the green sea turtle is being monitored in the backroom facility of Kaiyukan, but it is steadily recovering its health.
The aquarium spokesman says, “Besides sea turtles, there have been reports of seabirds and whales accidentally swallowing plastic waste. In the future, we are thinking of exhibiting the excreted plastic waste at the aquarium in the hope that it would become a good opportunity for people to think about the environment.”
Accidental Swallowings and Fishing Net Entanglements Increasing
The problem of plastic floating in the ocean is becoming more serious. It is estimated that more than 8 million tons of plastic waste ー which does not decompose naturally ー flows into the ocean each year. There is also a forecast that the weight of marine plastic waste will surpass the total weight of fish in the ocean by 2050.
According to the World Wide Fund for Nature (WWF), around 700 species of marine mammals such as seals, sea turtles, fish, and seabirds, have been injured or killed by marine debris. In more than 90% of the cases, the damage stems from being entangled in plastic fishing nets or consuming plastic bags mistaken for food.
Various countries are urging countermeasures in response to the current situation. On the 3rd of this month, the European Union (EU) enacted a new regulation that includes a ban on the market distribution of disposable tableware and food packaging made from plastic or foamed styrol. The Japanese government has also set a goal to reduce disposable plastic by 25%, and to reuse or recycle 60% of plastic containers and packaging by 2030.
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(Read The Sankei Shimbun article in Japanese at this link.)
Author: Yumi Kamioka, City News Department
Check this link to learn more about the Kaiyukan, its programs, research activities and exhibits. This article is part of a series. In each installment, Aquarium keepers will introduce episodes related to the living creatures that live at the Kaiyukan Aquarium in Osaka’s Minato Ward.
