The author of The Eastern Evil
If the Yellow River of the Yangtze River is the mother river of the Central Plains, then the Pearl River is the mother river of the Lingnan region, and the 774 tributaries it extends have bred rich fishery resources and provided food resources for the survival of Lingnan people. According to statistics, there were 380 species of freshwater fish in the Pearl River before the 1980s, and the fishermen's catch in the Pearl River reached 20,000 tons during that period, which shows that the fishery resources of the Pearl River are still relatively rich.
Later, with the arrival of some exotic species, the ecology of the Pearl River gradually changed, the living space of native fish was further compressed, and some rare fish were on the verge of extinction. Recently, some anglers caught a shrimp the size of a wrist on the Pearl River, which was confirmed to be an exotic species of Giant River Prawn. According to the introduction of fishing friends, he found many shrimp eggs in this shrimp, which indicates that this type of creature has gradually "settled".
Many netizens are worried about the ecological situation of the Pearl River, believing that the arrival of Giant River prawn will be like other exotic species before, resulting in the already fragile ecology becoming more fragile. So what kind of changes have occurred in the ecology of the Pearl River Basin due to the emergence of alien species? Did Giant River Prawn also become a "settled" alien species and then "bully" native species together?
<h1 class="pgc-h-arrow-right" Data-track="5" What impact do > alien species affect the Pearl River Basin? </h1>
The ecology of the Pearl River Basin was relatively good in the 1980s and 1990s, and fishermen were able to catch many native fish on the river, but after entering the 21st century, the fish composition of the Pearl River gradually underwent structural changes, and the fundamental reason was that a large number of foreign fish were mixed in. These exotic fish themselves have strong adaptability and reproductive ability, and when they reach the Pearl River, which is a better ecological environment, they are breeding and expanding their populations.
By 2011, aquatic experts specializing in the fishery resources of the Pearl River had found that there were problems with the survival of native fish species in the middle and lower reaches of the Pearl River, and their populations had been declining since the 21st century, such as the seven-silk mackerel, yellow jawfish and Cantonese bream, which was caused by the invasion of exotic fish species. Originally widely distributed in the Pearl River and Hainan Island basins, Cantonese bream was caught at least 15 tonnes in the 1980s, but only 5 tonnes remained after 2000.
Of course, the pollution of the aquatic ecological environment and the overfishing of fishermen are inseparable from the reduction of the population of The Cantonese bream, but the exotic fish species are also responsible, and they have robbed many of the food resources and living space of the local fish species such as the Cantonese bream. So which exotic species have "settled" in the Pearl River? The most common should be tilapia, almost all the tributaries of the Pearl River can see tilapia, which shows how widely distributed it is.
According to reports, in some watersheds of the East River, the proportion of tilapia in Hanoi has reached 30%, which shows that tilapia has "settled" in the area. There are many exotic species like tilapia, such as the leather-bearded catfish, the short-lipped giant carp, the Brazilian turtle and so on. According to data released by the Ecological Survey Agency, the number of exotic fish species in the Pearl River region has increased from 3 in the 1980s to 12 in 2015.
< h1 class="pgc-h-arrow-right" Data-track="17" > will there also be a negative impact on Giant River Prawn? </h1>
Giant river prawns are relatively large, with males reaching a length of 60 cm and weighing up to 1 kg, which will pose a threat to many native aquatic organisms if mixed into the Pearl River basin. Giant shrimp roche is popular for its high protein, tender meat, China introduced this species from Japan in 1976, and then began to artificially cultivate this shrimp, the market price is not low, at least 40 yuan a pound.
Why do shrimp like this as meat cause concern? The reason is that Giant river prawn is very destructive, it is an omnivore, not only eat plankton, but also eat small crustaceans and insects, the key is that its appetite is very large, the growth rate is also very fast, can grow about 15 cm a year, so the cost of artificial cultivation of Giant River shrimp is not low. Once such creatures escape into the wild to develop, they will rob the food resources of native fish and squeeze the living space of native fish.
However, aquatic experts believe that the possibility of Roche giant shrimp flooding in the Pearl River is relatively small, first, because in the existing fish structure of the Pearl River, many fish are for the eggs and seedlings of Giant River prawns, such as tilapia, perch and scavengers, who eat shrimp eggs when they see them. Second, because of the poor environmental adaptability of Giant River Prawns, it is more suitable for survival in water at 23 degrees Celsius to 30 degrees Celsius, and once the water temperature is lower than 14 ° C, it will freeze to death.
summary
Although the possibility of Giant River Prawn currently flooding is relatively small, it is also necessary to be wary of the possibility of its flooding, because the average temperature in Guangdong in the past two years is not high, but Giant River Prawn can still survive in the wild, and it is likely to "settle". Regarding the impact of Giant River P. roche on the ecological environment, further investigation and research by relevant departments and researchers is needed.