In the yellow sea of China, the "big star 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.
Screenshot of CCTV News
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, Red Star News joined hands with the Zhihu Q&A community and invited outstanding creators to give us professional answers.
Creator: Zhihu @ A man is wandering
Introduction: Science science blogger; excellent answerer of animals, oceans, marine life and other topics; know the science of salt researchers, know the arbitrator.
Weibo: @ Wanderer who wants to get fat
Short answer:
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. The spiny sea car was originally a common species native to the Yellow Sea, coastal residents have long known that it can be eaten, and many fishing communes have fished it specifically to save lives during natural disasters in three years, but they have not been eaten and extinct. One is that it is difficult to be eaten and extinct because of its unique life cycle, and the other is that not everyone in every region has a particular preference for it.
For Qingdao people, the latter is more prominent. The spiny sea pan car is a seafood that can barely be eaten by Qingdao people; The Philippine clam is a fate for Qingdao people.
Finally, starfish floods are far more harmful than most confidants think, and large-scale starfish outbreaks are fatal to many seafood farming.
Detailed answers:
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.
From its higher latitude of the original distribution point of view, the multi-spined sea pan car should not like high temperature waters, the existing research also shows that the multi-spined sea pan car is not too fond of too deep waters, water temperature and water depth should be able to lock it firmly within the original habitat range, so in China's territory, the multi-spined sea pan car is basically only distributed in the Waters of the Yellow Bohai Sea, especially the shallow water, the water temperature is also relatively cool Liaodong Peninsula coast, the central Bohai Sea, the water near the Long Island at the junction of 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.
The body shape of the spiny sea plate car is originally very flat, the entire digestive system is occupied by two stomachs a large part, the intestine can only be compressed very short, it is conceivable that its digestion efficiency is extremely low, the most optimistic estimate, the multi-spined sea plate car can only digest 5.7% of the food it swallows, which directly leads to it eating almost all the time.
The sea cucumber king who was forced to death by the spiny sea pan car and another kind of starfish (petrels).
The digestibility is too low, the spiny sea pan car must have a preference for food selection, it prefers to those shellfish that are moderate in size (too small shellfish are not enough to fill the stomach, too large generally have thicker shells), the closed shell muscle is relatively weak (the closed shell muscle is the secret of the double shell shell "hugging" the double shell, the strength of the closed shell muscle directly determines the difficulty of the starfish to "hard pull" the shell), or rarely hide under the deep sediment (avoiding the time it takes for the starfish to dig shellfish), so there is only one shell of abalone, The oysters, which are completely exposed to the reef and cannot escape and escape, and the Other Protagonist of this story, the Philippine Clam, are often its "stomach ghosts".
The direct unlucky egg of the disaster - the Philippine clam
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.
The different designations reflect both the widespread distribution of the Philippine clam in China and proof that coastal residents are familiar with and favored by it. Since the 1970s conquered the southern earthen pond nursery technology of Philippine clams, this small clam has blossomed everywhere on the north and south coasts, and in recent years, the Philippine clams have been at the top of the list of the highest mariculture production in China with an annual output of 3 million tons and 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.
PS: There is still controversy as to whether the Philippine clam is the single species of seafood with the largest scale and highest yield in the country. According to the Annals of Fishery Statistics for each year, oyster production is actually higher than that of "clams". This is because the statistical method of the "Yearbook" only pays attention to the large categories, and ignores the distinction between individual species, the oysters farmed in China vary according to the differences in the local environment, and the mainstream is at least the long oyster, kumamoto oyster, Fujian oyster, Hong Kong oyster and Omi oyster, and although domestic clam farming also has many species, the Philippine clam has always been the leader. Another point of controversy is whether the yield of kelp is higher than that of Philippine clams, because the kelp counted in China's "Yearbook" uses dry weight, while clams and other shellfish are fresh weight, according to the ratio of fresh / dry weight conversion, the fresh weight of kelp is definitely much more than that of clams. Of course, this does not affect the basic point of this answer, that is, "the Philippine clam is an extremely prominent and important marine economic shellfish", which is hereby listed for your reference (thanks again to @Li Xiaodong for correcting).
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 phrase - "drink (pronounced "Ha") beer to eat clams (pronounced "Gala")," and drink beer in the sea breeze to eat Philippine clams is the most authentic style of Qingdao people, and it is said that it is precisely because of this eating habit that the proportion of male gout in coastal areas of Shandong far exceeds the national average. According to the statistics of previous years, Qingdao citizens eat at least 50 tons of Philippine clams every day, and the questionnaire survey shows that 90% of Qingdao people will buy Philippine clams at least once a month, 74% buy at least once every half a month, and even 3% of citizens almost do not fall every day... It's underneath!
Why are Philippine clams popular? Because it's filling, delicious and easy to cook. However, not only the Qingdao people who hold this view, but also the spiny sea pan car is very much in agreement - the Philippine clam is its most perfect hunting target, its body size is moderate (about 2 to 4 cm, 6 to 10 g), the closed shell muscle is relatively weak, and it rarely buries itself deep like a clam, and it is particularly important that the huge scale of breeding brought by the strong demand of coastal residents makes it everywhere.
Here is a rough introduction to the Philippine clams "enough, delicious and cooking to save trouble": as mentioned above, the Philippine clams are the largest amount of seafood in China, there is no one, its price is also because of the long-term stable supply and relatively close to the people, generally is a few dollars a pound; delicious, this is a concept that varies from person to person, but for Qingdao people, this is undoubted; cooking is convenient, I have indeed not seen cooking more convenient ingredients than Philippine clams, the simplest way is to wash it and throw it directly into the pot No condiments are needed, no water is added, and it can be served when it opens its mouth.
Starfish outbreaks in previous years
At the end of March 2007, qingdao Philippine clam main production area of Hongdao outbreak of multi-spined sea pan truck disaster, by mid-April, the Area of Philippine Clams in Hongdao Breeding Area reached 60%, the mortality rate of clams in some breeding areas even reached 80%, a 60 horsepower fishing boat can fish out a ton of spiny sea pan trucks a day, and Qingdao's output loss of more than 100,000 tons during the entire breeding season.
In fact, this is not the earliest and most serious starfish disaster in Qingdao, just a year ago in July 2006, Qingdao's Laoshan, Huangdao and Jiaonan and other places have been subjected to a round of "starfish invasion" composed of spiny sea pans, petrel starfish, more tragic than the 2007 time, the aquaculture products in these areas are generally more expensive abalone and ginseng, the most affected Huangdao street back bay, 10 abalone farmers have lost more than 10 million, and the house price in the area in the same period is only 2000 ~ ~ 3,000 yuan / square meter; in the abalone breeding pond in Ganshuiwan, Xuejiadao Street, the density of starfish even reached 300 per square meter.
Further back, the multi-spined sea pan truck disaster had already broken out in Tottori Prefecture, Japan as early as 1974, when the breeding and stocking of Dongfeng snails was almost eaten by the multi-spined sea pan car; 7 years later, in Japan, the multi-spined sea pan car killed the released cockles.
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.
Bold Australian shoefish
A spiny sea car on the seabed off the estuary of the Derwent River in Tasmania, Australia
How did the Spiny SeaCar (and other starfish) disasters break out?
According to the description of old fishermen, starfish has always existed, but has never seen so many starfish floods before, which has to be linked to the rapid changes in China's coastal 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 booming development 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.
Studies from Australians who have been attacked by spiny carts in recent years have found that in the native distribution area of spiny carts (which is where we are), there is a boom-decay-boom cycle, which can be considered the result of their interaction with benthic shellfish. Whether it is shellfish or starfish, are extremely fertile, but the offspring survival rate is very low R strategy reproductive mode, if the survival rate of shellfish suddenly becomes high in a certain year to bring a bumper harvest, starfish is easy to increase food and rapid outbreak, and then due to excessive consumption of food can not support the huge population and collapse, so the reduction of natural enemies once again spawned a bumper harvest of shellfish, and the cycle began. However, the scale of the starfish outbreak cycle in the original ecology is limited, because their natural enemies also follow such fluctuation laws, but now, the ceiling is raised and the explosion threshold is lowered to make this fluctuation more and more out of control.
Is there a way to eradicate or reduce the scourge of starfish infestation?
The first is the idea that many friends have imagined by eating to try to eliminate some kind of biological outbreak (or biological invasion) threat, which has been proved to be completely unworkable by countless instances.
Friends have mentioned crayfish (protocellfish), the same example is bullfrog, crayfish and bullfrog are very popular in street food, there are many farmers in the country to make 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. Poachers are willing to hunt rhinos, even if it's the last one on earth, mainly because it's more profitable; but crayfish and bullfrogs already have a well-established farming system, and the cost and efficiency of large-scale farming is far more cost-effective than if you go out into the wild one by one— if you don't believe it, you can try to catch a hundred and eighty pounds in the ditch where "your house is full of crayfish" (this is the amount of a lobster shop uses in one night), and then calculate your time and labor costs.
Even if you do, through extraordinary cooking, unparalleled publicity, and even creatively link starfish with the secret recipe of health medicine aphrodisiac, so that it becomes a best-selling seafood, then the end result is mostly that coastal fishermen will fish first, and when the cost and efficiency of fishing fall to the point where they cannot compete with artificial breeding and breeding technology, they will fully switch to farming it. And for creatures like starfish with an astonishing rate of reproduction, if there are no other problems such as habitat destruction or seawater pollution, the remaining wild starfish will always recover quickly.
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.
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.
Specific to the scale of losses of the affected farmers, it is not easy to determine, some farmers contracted hundreds of acres of sea area, the annual release of seedlings is in the scale of several million, and there are 2 or 3 years old in the sea, has reached the marketing standards of the Philippine clams have not had time to harvest, may also be damaged. The duration of the disaster of the spiny sea pan truck is often very long, which is likely to make farmers lose confidence, affect the release of seedlings this year, and then affect the production of the next and subsequent years.
Studies of the life cycle of starfish have shown that from the fertilized egg to the adult starfish, they also need to go through the stages of feather larvae, short-wristed larvae, larvae, etc., of which the starfish in the feathered larval stage live completely in plankton, and the starfish in the short-wristed larval stage will find some fixed objects to climb on and live a settled life for a while. There is a view that starfish can be fished as much as possible by catching plankton at the feather larval stage, but this brings a new problem - the larvae of other marine organisms will also be fished up; in the short-wristed larval stage, some hemp rope and the like can also be put into the sea to attract them to attach and salvage, but there are many attachments in the sea, such efficiency is questionable. At present, it seems that the most effective way is to salvage a large number of mature adult starfish before the arrival of the breeding season of starfish according to the different water temperatures in various places, but this salvage also faces cost problems, and starfish disasters do not occur every year, it is inevitable that fish fishermen will have a fluke mentality, unwilling to willingly bear the heavy salvage costs when they have not seen the disaster.
Fertilized eggs (A), intestinal embryos (B) and feathered larvae (C) of the spiny sea tray car
But these approaches are palliative rather than symptomatic. 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.
At the end of the day, we're used to thinking of using natural behavior as "free." The starfish crisis is just telling us once again – It's wrong.
Red Star News reporter Wang Tuo comprehensive report
Edited by Zhang Li
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