Recently, there was a terrifying scene off the coast of Wakkanai City, Hokkaido, Japan, where a large number of sardine carcasses washed ashore for at least 10 kilometers. The cause of death of the sardines is reported to be unknown, but it is possible that the water temperature has dropped rapidly. This is the third mass sardine death in Japan in recent times, following similar cases in Aomori and Kumamoto prefectures. Why do sardines suffer so often? How do they affect our lives? Let's take a look.
The sardine is a migratory marine fish that belongs to the herbivorous species and is at the bottom of the marine biological chain and is the food of many large fish species**. Sardines usually move in groups, up to 1 billion swim together. Sardines have a wide range of distributions, mainly along the American coast of the eastern Pacific Ocean, the Asian coast of the western Pacific Ocean, and the southern coast of Africa. There are three main types of sardines in Japan, namely and They are generally between 13 and 20 cm in length, have different spawning periods, and have a lifespan of about 3 to 8 years.
Sardines are sensitive to environmental changes, and their temperature range is 10 20 degrees Celsius, and the minimum water temperature is 8 9 degrees Celsius. If the water temperature is too high or too low, sardines will develop a stress response that leads to a weakened immunity, susceptibility to viral or bacterial infections, and even outright death. In addition, sardines are also affected by other factors such as water quality, oxygen, food, predators, etc. Sometimes, sardines rush into rivers or harbours to escape predators, only to suffocate to death due to lack of salinity or oxygen. Sometimes, sardines can accidentally ingest poisonous plankton or algae, causing poisoning and death. Sometimes, sardines die in large numbers due to red tides or other marine hazards.
Although sardines are not the main food of humans**, they have an important impact on our lives. Sardines are an important part of the marine ecosystem, they are not only food for many fish, birds, mammals, but also regulate the balance of nutrients and carbon dioxide in the ocean by eating plankton. Sardines are also a high-protein, low-fat, high-in-the-dark fatty acids and trace elements that are beneficial to human health. Sardines can also be made into fishmeal, fish oil, fish fertilizer and other products, which are used in aquaculture, chemical industry, agriculture and other fields.
Sardines are small but beautiful sea creatures that play an important role in the ocean and also bring benefits to human life. However, sardines are also fragile creatures, and they are susceptible to changes in their environment, leading to mass deaths. As oceanographer Jack Cousteau said, "The ocean is the cradle of life and the future of life." ”。We should pay attention to the survival of sardines and protect the ecological balance of the ocean, so that sardines and we can have a better future.