It is reported that “Antarctic krill (Euphausia superba) is eaten 300 million tons per year by humans,” which is impressive. Although Antarctic krill is a fantastic marine organism (according to incomplete statistics, there are about 500 million tons in the world), according to the statement that 300 million tons are eaten every year, the world’s Antarctic krill is not enough for two years. So, do humans really eat 300 million tons of krill every year? Why isn’t Antarctic krill extinct? Let’s briefly discuss these two issues.
1. First, let’s briefly understand Antarctic krill
Antarctic krill gives us two pieces of information, one in Antarctica, and the other is krill. In fact, the same is true. Antarctic krill is a shrimp mainly distributed in Antarctic waters, and it belongs to the krill genus Euphausia. That is to say, the name Antarctic krill is a combination of the distribution and species classification of this organism.
Antarctic krill are widely distributed in the waters near Antarctica, and they can be seen in groups from a few hundred meters to more than 2,000 meters in the deep sea. Antarctic krill have fluorescent substances, they can be found through fluorescence even in the deep sea, especially a large group of glowing krills, which are truly beautiful.
Antarctic krill is a cornerstone species in the Antarctic waters because their large number provides a continuous source of energy for much marine life, such as penguins, turtles, whales, etc., especially blue whales, blue whales as the largest animal in existence and Its leading food is krill. Adult krills have an average body length of about 6 cm and weigh only about 2 grams each. They feed on marine plankton, such as diatoms that are only 20 microns.
2. Annual loss of krill
Although krill lives near Antarctica, its vast population has attracted a large number of fishing boats from all over the world. According to statistics, the annual catch of krill is about 30,000 tons, which is equivalent to killing tens of thousands of adult Asian elephants. In addition to our foreign countries, seven countries in the world are the “main force” for krill fishing.
A statistical report from 1973 to 2015 shows that in these 42 years, the world’s catch in 1981 was the highest, as high as 550,000 tons. In general, the total annual catch of krill around the world averaged Around 250,000 tons, not the 300 million tons as rumored.
3. Seeing this, some will say: This is just the amount of people fishing, isn’t there still marine life?
Of course, these 250,000 tons is indeed an annual human catch, and in the ocean, there are indeed many creatures that feed on krill. However, the sum of these animals’ predation of krill is far less than that of humans. First of all, blue whale, the marine organism that consumes the most krill, can eat about 6 tons of krill a day, so that a blue whale can eat 2136 tons of krill a year.
For 10,000 heads, they can eat more than 20 million tons of krill in a year. But one thing we need to pay attention to is that blue whales mainly feed on krill, but there are many types of krill. There are currently 85 known krill species, but blue whales do not live near Antarctica all year round.
Therefore, many of the marine organisms we see the feed on krill, not just Antarctic krill. Relatively speaking, in addition to humans, only Antarctic penguins can only eat Antarctic krill. Therefore, even if the consumption of Antarctic krill by marine organisms is added, the annual consumption of Antarctic krill will not exceed 100 million tons. In terms of the ratio of the amount of stock and consumption, it only takes 5-8 years for Antarctic krill to be eaten and extinct. However, it has been recorded that large-scale fish.
4. Of course, even the annual consumption of about 100 million tons accounts for 1/5 of the Antarctic krill. Why is the Antarctic krill not eaten?
According to the ratio of possession and consumption, it only takes 5-8 years for Antarctic krill to be eaten and extinct. However, there have been recorded large-scale fishing of Antarctic krill for 47 years, and the number of Antarctic krill is still not extinct. Why is this? There are two reasons.
- Strong reproductive ability
At the moment, a species that is consumed in large quantities, if it is not to be extinct, the necessary condition is to have a robust reproductive capacity, which is the case with Antarctic krill. Antarctic krill is a bisexual oviparous organism. An adult female Antarctic krill can lay an average of 8,000 eggs at a time. Looking at the entire nature, there are almost no creatures that can give birth to 8,000 offspring at a time, and it is such a tremendous reproductive capacity that the Antarctic krill can still maintain the population under such large consumption.
- Appropriate production timing and unique incubation process
Although the temperature in the waters near Antarctica is shallow and there is no distinct differentiation of the four seasons, Antarctica is divided into warm and cold seasons. From November to March of each year is the warm season of Antarctica, and the main breeding period of Antarctic krill It is concentrated in the period from January to March each year, which is the period of the Antarctic warm season so that the warmer seawater is conducive to the hatching of krill eggs.
The second is the incubation process. In general, the hatching of eggs is static. For example, fish will lay eggs on aquatic plants, preventing the eggs from being washed away and reducing the hatching rate. However, the hatching of Antarctic krill eggs is mobile. When spawning, the female Antarctic krill will lay eggs in the shallow sea. After the spawning is completed, the krill eggs will begin to sink. The entire sinking process will last for about three weeks. They drop from the shallow sea to 2500 meters. In the deep sea area of the sea, the entire incubation process is completed. After the incubation is completed, the small krill begins to float slowly and reaches the shallow sea again from the deep sea.
This unique hatching process keeps most of the krill eggs and larvae in the deep sea for a while, so that predators in different established seawater layers can only prey on a small part of the phosphorus shrimp, thereby significantly improving the survival rate of Antarctic krill eggs.
Nicol, S., Foster, J. and Kawaguchi, S., 2012. The fishery for Antarctic krill–recent developments. Fish and Fisheries, 13(1), pp.30-40.
Atkinson, A., Siegel, V., Pakhomov, E.A., Rothery, P., Loeb, V., Ross, R.M., Quetin, L.B., Schmidt, K., Fretwell, P., Murphy, E.J. and Tarling, G.A., 2008. Oceanic circumpolar habitats of Antarctic krill. Marine Ecology Progress Series, 362, pp.1-23.