Pike crab production has been increasing year after year Why are fish stocks getting less and less?

Qingdao opened to the sea on September 1, but the whole of August became the world of pike crabs, and a large number of pike crabs from the Zhoushan Islands to Haizhou Bay went north to Qingdao, which greatly enriched the tables of island city residents. In September, Qingdao's local pike crab, which has completed the last return of its shell, will surface and be perfectly listed. According to the survey of the Department of Oceanography and Fisheries, in the past five years, the production of pike crabs has increased year after year, and the price has been lower year by year, the price per kilogram has ranged from more than 10 yuan in the morning market to 40 or 50 yuan for commercial supermarkets. However, the public will also find that most of the seafood brought back by fishermen is small seafood, small fish, shrimp, pike crab, and larger turbot has become a "rarity". What are the reasons behind this?

The seafood market became the world of pike crabs

The reporter learned from the interview that since August, the southern pike crab has begun to go north in large quantities, most of which are from Lianyungang in Jiangsu Province and Zhoushan in Zhejiang Province. "Southern pike crabs have come in large quantities since August, and the largest daily shipments are also pike crabs. Mr. Qu, a seafood merchant, said. Isn't it time to eat crabs now, crabs are starting to get fat, the key is that the price is cheaper, which can relieve the family. Ms. Lu, a citizen who lives in Laoshan, told reporters that the price of crabs has been reduced for a while, which has made the family who love crabs feast. In the Maidao Seafood Market, stall owner Ms. Zhou told reporters that this year's crab prices are cheap, especially in the past half a month, crab prices have dropped again and again, "it is estimated that there is no head drop, it is almost past the Mid-Autumn Festival, almost this price." The reporter saw that Ms. Zhou's stall had 8 glass water tanks, of which 4 water tanks were barracuda crabs, "Now is the time to sell crabs, at least more than 100 pounds a day." ”

In the morning market in the city, the price of medium-sized fresh pike crabs has dropped to about 20 yuan / catty. In some farmers' market seafood stalls, half of the stalls selling pike crabs, filling the market with pike crabs. Due to the large amount of listing, some wholesalers no longer stick to the market, and begin to enter the community to organize group purchases and deliver to the door, and the price is cheaper. The price of four or two pike crabs once fell below 20 yuan per kilogram.

Three major reasons increased production of pike crabs

In recent years, pike crabs have been harvested year after year along China's coast, but the recovery of fishery resources such as large fish has yet to be observed. Cui Zhaoxia, a professor at Ningbo University, believes that there are three main reasons for the bumper harvest of pike crabs along the coast of China: the increasingly strict fishing policy; the increase in sea temperature is suitable for the growth and reproduction of pike crabs; and the expansion of pike crab populations brought about by breeding and stocking.

The reason for the increase in the production of pike crab in recent years is mainly due to the extension of the fishing moratorium and the strict protection of fishery resources. In the 1970s and 1980s, the adult growth period of pike crabs could reach 3 years. However, in recent years, with the increase in the catch of fishing vessels, the growth period of pike crabs has been shortened to one and a half years. May and June are the fastest and best time for marine life, and the seasonal fishing moratorium gives the best conservation of these fishery resources. In particular, this year's fishing moratorium was advanced by one month, giving seed crabs and small crabs a longer protection period, and small crabs were well protected, so that the production of large crabs has increased year after year.

The main production areas of pike crabs in the whole country are mainly distributed in Zhoushan Fishery, Haizhou Bay Fishery (lianyungang and Rizhao intersection), Shandong Peninsula and Liaoning coastal waters. Since August 1, fishing vessels operating on truss-dragged shrimp, cage pots, gillnets and light fences (shiki) nets in the East China Sea have ended their seasonal fishing moratorium, which has lifted the ban on pike crabs in Haizhou Bay and Zhoushan. After entering August, the largest amount of seafood in Qingdao is the sea crab. Lianyungang is located in northern Jiangsu, the beach area is very large, the local fishermen will be a large area of the beach fence into the crab fry, to the harvest season of the fishing season directly on the line. Because of the large area of the beach, the production of pike crabs in Lianyungang is often relatively large, which is also the reason why the price is relatively cheap.

Secondly, from an ecological point of view, the increase in the production of pike crabs may be related to the water temperature environment, the level of temperature directly affects the growth rate of pike crabs, due to the continuous high temperature this year, the water temperature is basically maintained at a temperature that is very suitable for the growth of pike crabs. In such a marine environment, pike crabs not only produce large yields, but also show the characteristics of increasing fat.

Finally, the increase in the production of pike crabs is closely related to the planned breeding and stocking of the government. Haizhou Bay is a relatively obvious ecological distribution line in the north and south of the Yellow Sea, according to the characteristics of Haizhou Bay and combined with the city's years of implementation of marine breeding and stocking practices and breeding effect tracking and evaluation, the input-output ratio of Pike crab seedlings can reach 1:10. The release of pike crabs off the coast of Qingdao has lasted for nearly a decade, and the ecological benefits are also very objective. Since August 1, Zhejiang, Jiangsu Province, has allowed some fishing vessels to go to sea, including drift-gill fishing vessels specializing in pike crabs, mackerel and pomfret. The main target of phylloscopic fishing vessels is pike crabs, and half of the marine fishing vessels in Lianyungang are lentilever operating types. Every day, a fishing boat full of sea crabs docks and then travels north to Qingdao by land to sell. In September, Qingdao's local pike crabs began to increase, but the price will also rise slightly.

Expert analysis

Changes in the population structure of fishery resources

Although the production of pike crabs has increased year after year, both Cui Zhaoxia, a professor at Ningbo University, and experts from the Yellow Sea Fisheries Research Institute have expressed their concerns while being happy. Cui Zhaoxia believes that as the sea temperature gradually increases, the total amount of plankton and plants in the ocean declines, "The phytoplankton in the sea are the bait for fish and pike crabs, and the pike crab is at the top of the food chain in the ocean." This means that more and more pike crabs will "compete" with large fish upstream in the same food chain, and the less food they have, the less conducive it is to the survival of large fish. In addition, from the perspective of human factors, in recent years, major coastal provinces and cities have increased the breeding and stocking of pike crabs, and the huge increase brought about by the release into the sea before the start of the annual fishing moratorium is also one of the reasons for the bumper harvest of coastal pike crabs. Big fish eat small fish, small fish eat shrimp, which is the law of fishing grounds for thousands of years. In the eyes of fishermen, the barracuda crab has been harvesting abundantly year after year and "running rampant" in the sea, which indicates the arrival of "shrimp soldiers and crabs will be called kings", and it is difficult to see changes in the situation of fewer fish along the coast in the short term. Experts are not without concern that the growth of pike crabs also reflects the lack of fish resources in the Yellow and East China Seas. We can think of the Yellow Sea and the East China Sea as a typical ecological environment, then its volume is fixed, once one organism is particularly more, it means that other organisms are relatively few.

Experts from the Yellow Sea Fisheries Research Institute told reporters that striped fish, yellow croaker, silver pomfret, semi-slippery tongue fish, Chinese shrimp, etc. are all high-quality resources that were common in the Yellow Bohai Sea 20 years ago, but from the current research, the traditional resources such as large yellow croaker and wild Chinese shrimp are on the verge of exhaustion, and the resources of various traditional high-quality marine species such as Chinese shrimp have declined significantly, and it is difficult to form a fishing flood. From the perspective of the population structure of fishery resources, small pelagic fish, cephalopods, small shrimp and crabs with short life cycles and low trophic levels have gradually replaced the original large-scale high-quality economic species. According to a large number of research data from the Yellow Sea Fisheries Research Institute, the Yellow Bohai Sea, which was once known as the "cradle of fishery" and "natural fish barn", was a high-quality fish species in the 1960s as striped fish and small yellow croakers. In the 1980s, it was dominated by yellow crucian carp, spiny plumtail and kong ray. In the early 1990s, it was dominated by anchovies, red-nosed mackerel and spotted crayfish, and now it is dominated by goby. The waters of the Yellow Sea are now dominated by fine-striped lionfish and sturgeon, and there is still a certain production of small yellow croaker and mackerel, but it is far less than that of that year. The marine living resources in China's coastal waters have been in serious decline, fishing targets have been frequently replaced, and the decline rate of high trophic level trophic level is higher than that of the global level. To use the most popular words, most of the high-quality fish in the Yellow Bohai Sea in the 1960s were large-scale high-grade fish at the top of the food chain, but with the increase in fishing intensity, the high-quality main fish in the Yellow Bohai Sea gradually moved down the food chain level, and now it seems that there are more small fish and shrimp left.

Qingdao Evening News/Pocket Qingdao/Qingdao.com reporter Wang Wei

[Editor: Zhang Zhenzhen]