Jan 03, 2022 09:00:00

Can fish and other marine animals drown?

According to the World Health Organization (WHO), as

many as 236,000 people are drowning every year around the world, and drowning is a very familiar danger to humans. People who can't swim may have thought, 'I wish I were a fish or a dolphin,' but the scientific media Live Science asked, 'Can fish and marine animals living in the water also drown?' I explain the question.

Can fish and other marine animals drown? | Live Science
https://www.livescience.com/can-fish-drown.html

According to Frances Withrow, an oceanographer at Oceana, a non-profit marine conservation organization, 'Marine animals also need oxygen to live. While we take in oxygen from the air, they dissolve in water. I live by using the dissolved oxygen that is present. ' Humans drown because they cannot take in oxygen and suffocate in water, but marine animals do not have the same mechanism as humans, but they sometimes suffocate when they cannot take in oxygen in water.

For example, most fish take in dissolved oxygen in the water and emit carbon dioxide in the body by passing water through the gills. However, if the gills are damaged or if water does not pass through the gills for some reason, the fish will not be able to take in oxygen and will choke. The cause of the inability to take in oxygen from the gills is that the hook is caught and damaged, bacteria propagate and block the passage of water, and the bacteria decompose the gills themselves. “It's like we have a serious respiratory illness,” says Withrow.

Also, some fish can breathe gills while still, but fish such as tuna and bonito must constantly swim for water to pass through the gills. Therefore, if these fish get caught in fishing nets and cannot swim, they may suffocate as they are. Some sharks can't breathe gills unless they keep swimming, but malicious fishermen cut only the fins and throw the sharks into the sea to get shark fins, so the sharks with the fins cut off are suffocated. They can't do it and suffocate or are eaten by predators. 'These fishing methods are unsustainable and are often illegal,' said Withrow.

Fish basically breathe gills, while marine animals such as turtles and dolphins breathe lungs like humans. Naturally, these marine animals will die if they do not rise to the surface of the water and breathe, but there have been frequent reports of cases where they are caught in fishing nets and cannot breathe and die.

In particular,

it has been pointed out that gill nets , which are a type of gill net and can be used in the open sea, often mistakenly catch and kill many marine animals. According to Withrow, the drift net catches things that get caught in the eyes indiscriminately, so it also catches sea turtles and dolphins that fishermen do not intend to sell. In addition, there are cases where large animals such as whales get entangled in ropes stretched by humans and cannot breathe.

It is difficult to know how many marine animals are suffocated each year, but the International Whaling Commission estimates that as many as 300,000 whales and dolphins die from fishing nets each year.

There are also cases where 'there is not enough dissolved oxygen to breathe in the water'. If eutrophication of the water area progresses at once for some reason, a large amount of plankton will occur, red tide and blue tide will occur, a large amount of oxygen will be consumed in a short period of time, and fish living in the same water area will be suffocated. According to Withrow, although the ocean is connected, it takes time to mix with other bodies of water, so it is not always possible to quickly replenish the oxygen lost in one body of water.

In addition, since warm water has less dissolved oxygen than cold water , it has been pointed out that there is a risk that the amount of dissolved oxygen will increase in the sea area due to global warming.