Tonga volcano erupts, scallops run 9,700 kilometers to sneak to Zhangzi Island? Scallops: I can't run!

There is something strange happening with the scallops on Changzi Island again!

After the Tonga volcano erupted, it was rumored that a large number of scallops traveled 9,700 kilometers from the Pacific Ocean to Changzidao in two days, and this year's harvest will increase greatly, causing Changzidao's stock price to hit the daily limit.

This is not the first time that scallops have caused trouble. In the past few years, the scallops in Changzi Island have either "escaped" or "died suddenly", but this is the first time that they have "run back" to Changzi Island.

October 2014

Zhangzidao announced that due to the abnormal cold water mass in the northern Yellow Sea and other factors, all the scallops ran away. As a result, Zhangzidao suffered a huge loss of 1.189 billion yuan in 2014, shocking the A-share market.

January 2018

The company found that marine disasters led to a shortage of bait, causing scallops to starve to death, resulting in a huge loss of 723 million yuan in 2017.

January to March 2019

The scallops ran away again, and the company suffered a loss of 45.14 million yuan.

November 2019

A large number of scallops died suddenly, and the scallop yield per acre dropped by 90%. The company initially judged that there was a significant risk of inventory impairment.

However, if you believe it, you lose! The speed of scallops is less than half a meter per second, and they can only swim five or six meters at a time. The outrageous rumor that "scallops ran to Zhangzi Island" is pure nonsense.

Scallops, scallops, where are you from?

Common farmed scallop species in my country include Chlamys farreri, Chlamys nobilis, Argopecten irradians and Mizuhopecten yessoensis. The first two are local scallops, while the latter two are farmed species introduced from abroad.

Scallop farming has a long history in my country and is one of the country's important offshore farming pillar industries. The harvested products are exported all over the world. As early as the 1980s, my country introduced scallops from foreign countries for farming.

Chlamys shells of varying colours and sizes | Joanbanjo / Wikimedia Commons

The Yezo scallop, also known as the sail scallop, is native to northern Japan and the Russian Far East. It is a strictly cold-water species, so it is only farmed in northern my country, including Shandong and Liaoning. The other bay scallop, which was introduced from the east coast of the United States in the Atlantic Ocean, is similar to the native Chlamys farreri. It can tolerate a wide range of temperatures and salts, and its farming range in my country is much wider than that of the Yezo scallop. In addition to the northern coastal areas of Shandong and Hebei, it is also farmed in southern areas such as Guangdong. These two types of scallops are already available in seafood markets across my country.

Bay scallop shell | Naturalis Biodiversity Center

Can scallops escape and run back?

The life experience of scallops changes from drifting to taking root. This life has to start with the baby scallops. People mostly obtain scallop seedlings through artificial breeding. The selected scallop parents are carefully cared for in the breeding tank. After the male and female scallops release gametes in the water to form fertilized eggs, the fertilized eggs are collected and cultured in separate pools. Algae are fed to the hatched larvae to raise them. When the baby scallops that live in the planktonic life are about to settle down, plastic sheets are put in as attachments for the seedlings, and they are carefully cared for so that they can survive the most vulnerable seedling period.

When they are about 3 centimeters long, the baby scallops are transferred to offshore waters and farmed in cages suspended in the water (cage hanging style), or threaded through the shells and fixed to the main rope (ear hanging style), or even directly sown on the seabed (bottom sowing style) until they are put on the market. Scallops are filter-feeding organisms, mainly relying on filtering plankton, organic debris, etc. in the water as their food source, so no feeding is required in wild farming.

Ear-mounted and cage-mounted aquaculture | M. Dredge et al. / FRDC Project 2000 (2002)

Compared with hanging culture, bottom seeding lacks direct control over the species being cultivated. It is like herding sheep on a boundless grassland. In the absence of effective management, it is easy to reduce production and it is not easy to harvest. The advantage is that the cost of investment and maintenance is low. In the 1980s, Zhangzidao made its fortune by bottom seeding.

In comparison, the hanging culture model makes it easier to understand the condition of scallops and is convenient for harvesting, but it requires more daily maintenance to prevent the cages from becoming overcrowded with algae and sludge, which can cause adverse effects such as poor water flow. Of course, it also deprives the scallops of their freedom of movement and prevents them from "escaping en masse."

Harvesting cage-caged scallops | Tuchong Creative

In fact, the entire shape of scallops is very suitable for swimming (of course, relative to other shells): very flat, almost symmetrical, with rounded edges, and the joints between the two shells are very flexible. As long as the shell is opened quickly, water is sucked from the front, and then the front opening is covered with the marginal membrane, and then the shell is closed with all efforts, and the water is sprayed out from the back, swimming is achieved - it looks like Pac-Man eating seawater mouthful by mouthful.

Scallop swimming | Natural History Magazine

This trick is very effective in avoiding predators such as starfish, but it loses to real swimming creatures. Scallops can only swim up to one meter high and at a speed of no more than half a meter per second. They can only swim five or six meters at most before falling back to the bottom of the sea exhausted. They will probably need to rest for several hours to fully recover. When landing, they may fall in the wrong direction and land on their left shell. Fortunately, they have a righting reflex to turn back. (Yes, the two shells of shellfish are left and right shells, not front and back or upper and lower shells.) With this swimming ability, it was only two days after the Tonga volcano erupted, and the scallops rushed 9,700 kilometers to Zhangzidao? Don't talk nonsense!

However, in addition to swimming scallops, we can also see jumping shells.

Look at the scallop's eyes (the round, shiny black dots on the edge), and remember that it doesn't have an upper or lower shell, it has a left and right shell | wiki commons

Alien Giants and Dwarfs

Compared with the native Chlamys farreri, the Hokkaido scallop is a giant and the other is a dwarf. Hokkaido scallops are larger than Chlamys farreri and Chlamys farreri. The shell diameter of a large individual can reach more than 20 centimeters long (research shows that this "giant" scallop is at least 15 years old). The main aquaculture species of the famous Zhangzidao Island is the Hokkaido scallop. The common Hokkaido scallops on the market are generally about two years old and between 10 and 15 centimeters in size. On the back of the shell of the Hokkaido scallop, the radial "fan bones" are smooth, while the "fan bones" of the Chlamys farreri have thorn-like protrusions.

Ezo scallop | あおもりくま,(Aomorikuma) / Wikimedia Commons

The imported bay scallop is small in size, with an adult bay scallop only 5 to 7 cm, which is still small even compared to the Chinese scallop (regular size 7 to 9 cm). Bay scallops have the characteristics of fast growth and short time to market, and some varieties can be marketed in less than a year. The number of "scallop bones" on the back of the bay scallop shell is more than that of the scallop, and the shell is more round (the scallop is more triangular).

Bay scallop's tiny blue eyes | unoit333 / Flickr

The colors of Chlamys farreri and Bay scallops vary widely, while the Yezo scallops are less attractive, with one side being whiter and the other side being browner. Nowadays, due to the development of breeding technology, some scallop varieties that cater to market preferences have been cultivated, such as the "Zhongke Red Bay Scallop" cultivated by the Institute of Oceanology, Chinese Academy of Sciences, and the Nan'ao Golden Scallop (Glorious Chlamys farreri) cultivated by Shantou University, which are new varieties with pleasing colors, fast growth rates, and high meat yields.

Red and white crescent, how to eat scallops

The adductor muscle of scallops, which we often call scallop meat, can be eaten raw or cooked, and is also one of the ingredients for making the "Eight Treasures of the Sea" scallops. In addition to scallop meat, scallops also have various organs, the most attractive of which are the red and white gonads. White is male and red is female. Some hermaphroditic scallops have a peculiar mix of red and white gonads. In Japan, skilled sashimi chefs can even taste the different flavors of female and male scallops. The difference between the two colors only appears during the breeding period. After this period, the gonads of both males and females degenerate into a colorless and transparent state, and their appearance becomes the same.

The viscera of a Japanese scallop, red is female and white is male | Joanbanjo / Wikimedia Commons

Like sea urchin roe and crab roe, scallop gonads are most delicious during their breeding season in late spring or autumn. In continental Europe, delicious scallop gonads are even sold as delicacies. Scallop gonads do not need to be overcooked, just slightly cooked, taste slightly salty, and have a texture like animal liver. Because the scallop's white middle adductor muscle is superimposed on the outer edge of the red half-moon-shaped gonad, it looks like the sun and the moon, so it is also known as the sun and moon shell. By the way, the sun and moon shell is also the common name of another scallop: Asian sun and moon clam (Amusium pleuronectes).

In the world of scallop cuisine, scallop vermicelli is probably the most well-known. The scallops in some pre-packaged scallop vermicelli are not "original" - the scallop shells are pre-cleaned and well-presented blank shells, and the scallop meat is pre-removed from the scallops, frozen separately, and then combined to form the "pre-live" appearance.

Grilled scallops may not look the same as they do in the original | Pixabay

In addition to pre-packaged scallops with vermicelli, many people also buy individual scallop meat, which can be pan-fried, deep-fried, or rolled with bacon and crab roe to make Western dishes. You can also buy fresh live scallops at the market, remove the inedible gills and viscera, and the rest can be cooked into Western-style cream or cheese-baked scallops, Chinese-style steamed or vermicelli scallops. When eating scallops, don't forget to show off your knowledge of what species these scallops are and whether they are boys or girls.

As for the scallops on Zhangzi Island, which are dying and running around, we can only say: you can cheat people, but be careful about how many times you cheat! If you don’t want to be a leek, start with me!

Author: Seafood Knowledge, Revolucion

This article comes from the Species Calendar, welcome to forward

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