"Send a large army of stars" to invade Jiaozhou Bay, eat clams and scallops, and fishermen suffer heavy losses How to deal with them?

Source: Chengdu Business Daily

We've become accustomed to using natural behavior as "free."

The starfish crisis is just telling us once again – It's wrong.

In the Yellow Sea of China, the "Sending Star (Starfish) Army" is invading Qingdao Jiaozhou Bay in a mighty way.

According to CCTV News, Qingdao Morning Post and other media reports, a large number of starfish have appeared in the coastal waters of Qingdao Jiaozhou Bay in recent days, and each boat can catch one or two thousand catties or more per day. Because of the large number, fishermen carry them in baskets, transport starfish to the shore, and load them into cars to transport them to the market.

Starfish is good-looking, but a "beautiful killer". Because starfish feed on clams, scallops, etc., farmers suffer serious losses. After the Spring Festival this year, fishermen found a large number of starfish in the offshore area, and the clams they raised in the sea were also attacked by starfish and suffered heavy losses. "Starfish are omnivores that eat everything. A starfish can eat 10 clams a day, which is a staggering amount. "Many starfish swarms pass by, and the clams are eaten to the point where only their shells remain. Experts say that starfish have a strong reproductive ability, and there are almost no natural enemies after adulthood, and there is no control method. Starfish is rich in nutrients, and the more common ways to eat are: steaming, cooking, steaming eggs, soup and so on. Many netizens proposed that they can eat all the invasion starfish, but is this method reliable?

In order to explore the causes of the starfish disaster and possible ways to deal with it, Chengdu Business Daily- Red Star News joined hands with the Zhihu Q&A community to invite excellent creators @ A Man in Wandering (science blogger; excellent answerer of animals, oceans, marine life and other topics) to give us professional answers.

The starfish that flooded this time were Asterias amurensis, and the main clams that were killed were the Philippine clams (Ruditapes philippinarum). This is not the first time that the world, the whole country, and even Qingdao has been hit by a starfish flood, and I am afraid it will not be the last.

There is no good solution to starfish flooding at this stage, and the mechanism of its outbreak is very complex and elusive. All the answers advocating "eating" to deal with starfish disasters can be put to rest.

This time the disaster star - the spiny sea pan car

Let's first get to know the protagonist of this flood, the starfish, the Asterias amurensis. Starfish is a collective name for more than 1,500 species in the five orders of the echinoderm phylum starfish, and the spiny sea disc car belonging to the pincer echinosidaceae is the most common starfish species in the northwest Pacific Coastal Sea.

In China, the spiny sea pan car is basically only distributed in the waters of the Yellow Bohai Sea, especially along the coast of the Liaodong Peninsula, where the water is shallow and the water temperature is cooler, the waters near Long Island at the junction of the central Bohai Sea and the Yellow bohai Sea, and near the Yanwei Fishery in the north of the Shandong Peninsula. It can be seen that the coastal area of Qingdao, which belongs to the Yellow Sea, was originally in the natural distribution area of the spiny sea pan car, so this starfish disaster is not a biological invasion.

As a typical carnivorous animal, the adult spiny sea car predator is very fierce, and it especially likes to attack the hard bones that are smeared along the beach , shellfish protected by thick shells. When predation, the multi-spined sea pan car wraps the shell of the double-shell shell with its own wrist, and then uses brute force to directly pull it left and right, and the shellfish soft body that has lost the protection of the hard shell is exposed under the mouth in the center of the abdomen of the multi-spined sea pan car, at this moment, the multi-spined sea pan car will turn out one of its own stomachs - cardia stomach out to wrap the food, partial digestion and then swallow the food, and give it to the other stomach - the pyloric stomach to slowly process, while taking back the cardia stomach while looking for the next prey.

Because the digestibility is too low, the spiny sea car must have a preference for food selection, preferring to attack shellfish that are moderate in size (too small shellfish are not enough to fill their stomachs, and those that are too large generally have thicker shells), relatively weak closed shell muscles (closed shell muscles are the secret of double shellfish "hugging" double shells, and the strength of the closed shell muscle directly determines how easy it is for starfish to "pull hard" shells), or shellfish that rarely hide under the deeper sediment (avoiding the time it takes for starfish to dig shellfish), so there is only one shell of abalone The oysters that are completely exposed to the reef and cannot escape and escape, as well as the other protagonist of this story, the Philippine clam, often become its "stomach ghost".

The Philippine clam (Ruditapes philippinarum) has different names in different parts of China, in Liaoning and a few places on the Shandong Peninsula it exists as a clam; in other parts of the Shandong Peninsula, clam is its special name; continue south, people call it the flower clam or flower shell.

In recent years, the Philippine clam has been at the top of the list of the highest mariculture species in China with an annual output of 3 million tons, accounting for 15% of the total marine aquaculture in the country. Especially in Liaoning and Shandong provinces, whether from the production or consumption level, Philippine clams are the most important presence in coastal areas.

In Qingdao, the place where the starfish invasion occurred, the Philippine clam is no longer a simple shellfish, and the promotion of a large number of Qingdao stars has made many foreigners learn a Qingdao dialect - "drink (pronounced 'Ha') beer and eat clams (pronounced 'Gala')", blowing the sea breeze to drink beer and eat Philippine clams is the most authentic style of Qingdao people. According to statistics from previous years, Qingdao citizens eat at least 50 tons of Philippine clams every day. Why are Philippine clams popular? Because it's filling, delicious and easy to cook. In particular, the sheer scale of farming brought about by the strong demand of coastal residents makes it everywhere.

According to some data, at the end of March 2007, the main production area of Qingdao Philippine clams, Hongdao, broke out of the multi-spined sea pan truck disaster, by mid-April, the Philippine clam damage area in the Red Island breeding area reached 60%, the clam mortality rate in some breeding areas even reached 80%, a 60 horsepower fishing boat can fish out more than one ton of spiny sea pan trucks a day, and the output loss of Qingdao in the entire breeding season is more than 100,000 tons. Just a year ago, in July 2006, Qingdao's Laoshan, Huangdao and Jiaonan had already suffered a round of "starfish invasion" composed of spiny sea pans and petrel starfish, and what was even more tragic than the 2007 one was that the cultured products in these areas were generally more expensive abalone and ginseng, and the loss of 10 abalone farmers in the back bay of Huangdao Street, which was the most affected, had exceeded 10 million yuan.

In 1999, Tasmanian fishermen fished this never-before-seen starfish from the seabed, and since then, the spiny seacart has not only continued to endanger the local shellfish farming industry, but also continues to move north along the Australian coast, and the sharp decline in the local endangered fish species, the rough Australian carfish, is also likely to be related to the multi-spined sea car, the fish's egg clumps in the algal grove are preyed by starfish. It is reasonable to speculate that the juveniles of the spiny sea pan car followed the ballast water of the freighter to this new world.

How did the spiny sea car accident break out?

According to the descriptions of old fishermen, starfish have always existed, but have never seen so many starfish floods before, which has to be linked to the rapid changes in the offshore ecological environment in recent decades - starfish is not without natural enemies, a large number of fish, benthic large snails can effectively suppress the size of starfish populations, but with the boom of offshore fishing, predatory marine fish resources with higher economic value have dried up first, inadvertently raising the ceiling for the scale of starfish flooding.

Another view is that the flood of starfish and the rapid expansion of the scale of near-beach mud culture are also closely related, mudflat shellfish culture makes it easier for starfish larvae to find food, but also greatly promotes the carrying capacity of starfish populations in a certain sea area, and it has been proved that even in the 2006 and 2007 Qingdao starfish disaster outbreak season, the outbreak of starfish was limited to the vicinity of the breeding area, and the size of the starfish population in other nearby seas has been maintained at a normal level. According to this view, large-scale shellfish farming has lowered the threshold for outbreaks for starfish flooding.

Is there a way to eradicate or reduce the scourge of starfish infestation?

Is it feasible to eat?

This has been proven by countless instances to be completely unworkable. In response to some netizens proposing to "let foodies eliminate starfish", experts reminded that the starfish that people usually eat is actually its reproductive glands, which contain slight toxicity. Some people will have a crispy feeling in their mouth after eating, and it is recommended to eat less. It is best not to eat it for people who are weak and sick.

There are also mentions of crayfish (protocrayfish), the same example is bullfrog, crayfish and bullfrog are very popular in street food, there are many farmers in the country who have made a fortune by raising them, but this does not prevent them from continuing to become invasive species in China's wild water bodies, and you can't catch and eat them all.

Then we will discuss how to reduce and contain the harm of starfish outbreaks. Due to the earliest impact of the starfish outbreak disaster, Japan and the United States have gone the farthest in the field of preventing starfish outbreaks, but realistically speaking, they do not have a very good method, the common method is to soak the rope used for shellfish cultivation with lime, or sprinkle lime for extermination.

Fishing, can you fish out?

Our country is mainly based on fishing, but generally wait until after the outbreak of disasters to rush to start, and the cost is huge. For example, after the outbreak of the spiny sea car disaster in Qingdao, farmers actively carried out self-help, and more and more fishing boats were fishing for starfish, but they could not be fished. The starfish fished ashore can still be sold, the price of large individuals can reach 4 yuan / kg, but the cost of fishing has reached 3 yuan / kg, and with the fishing out of more and more starfish, the purchase price will definitely decline further, loss is the inevitable end, not to mention the use of the money earned by fishing starfish to supplement the loss of shellfish.

Root cause: imbalance of marine ecosystems

Starfish's high reproduction rate or big appetite, in fact, it would not have caused a catastrophe, it was originally clamped down by the natural balance layer by layer, but it is not a unique link in the marine benthic ecological chain. The root cause of starfish outbreaks is the imbalance of marine ecosystems, which are the result of the accumulation of many ecological crises. If this deterioration of the environment is not addressed from the root causes, even if the problem of starfish can be solved, other potential hidden dangers will always erupt.

Chengdu Business Daily - Red Star News reporter Wang Tuo