The postponement of the listing of hairy crabs is the curse of the continuous high temperature

Recently, hairy crabs in many places have been caught and listed, ushering in the peak of bookings before the National Day, and diners who have been waiting for many days sigh "Finally waiting for you"
.
Previously, due to the continuous high temperature weather, some hairy crabs in major production areas such as Yangcheng Lake and Taihu Lake were postponed
.

So, how does high temperature weather delay the growth and development of hairy crabs? Are other aquatic products also subjected to "roasting"? In this regard, the reporter of Science and Technology Daily interviewed relevant experts
.

Hairy crabs are so hot that their appetite decreases and it is difficult to gain weight

Xu Gangchun, deputy director and researcher of the Freshwater Fisheries Research Center of the Chinese Academy of Fishery Sciences, said: "This year's high temperature weather has had an impact on
hairy crabs.
Specifically, it is mainly reflected in three aspects
: late sexual maturity, slow growth and development, and delayed molting.
”

Hairy crab, scientific name Chinese river crab, is a widely distributed economic crab in China, also known as river crab, hairy crab
.
Hairy crabs generally begin to mature
rapidly in late September each year.
The delicious crab cream and crab yellow in people's mouths actually refer to the paragonadism of male crabs and their secretions, and the ovaries and digestive glands of female crabs
.
Both crab paste and crab yellow require hairy crabs to mature before they can be eaten
.
"Affected by high temperatures, hairy crabs have matured relatively late this year, which has greatly hindered their timely listing
.
" Xu Gangchun pointed out
.

It is reported that the most suitable temperature for the growth of hairy crabs is 18 to 25 degrees
Celsius.
When the temperature is higher than 25 degrees Celsius, the physique of the hairy crab will decline, and its appetite will gradually decrease
.
"In general, when the temperature reaches 30 degrees Celsius, the feed intake of hairy crabs decreases; Once the temperature exceeds 35 degrees Celsius, the hairy crab will stop feeding
.
Xu Gangchun said
.
This summer, the temperature of some hairy crab breeding areas in China is even approaching 40 degrees Celsius, and hairy crabs are so hot that they "don't think about tea", and it is naturally difficult to gain weight
.

In addition, a decrease in the feeding intake of hairy crabs can trigger a chain reaction
of prolonged molting.
"Hairy crabs need to molt multiple times to mature, and once the molting is delayed, its growth period will be extended
accordingly.
" Xu Gangchun said
.

"Although the autumn wind has risen, the temperature is not as high as before, but this year's hairy crab large-scale market or still need to wait until October
.
" And everyone should also be mentally prepared, affected by the high temperature, this year's hairy crab is likely to be smaller
than in previous years.
Xu Gangchun predicted
.

Aquatic plants hold up "umbrellas" for aquatic products

"In addition to hairy crabs, high temperatures can also have an impact on
other aquatic products.
For example, the kelp, sea cucumbers, freshwater fish, etc.
that people often eat, they will grow slowly under the influence of high temperatures, and even die
.
Xu Gangchun said, "Affected by high temperatures, it is not uncommon for aquaculture to reduce production or even cut off harvests in recent years
.
”

Temperature is one of the important factors affecting the content of dissolved oxygen in water, and dissolved oxygen is a necessity
for the survival of organisms in water.
High temperatures can reduce the content of dissolved oxygen in the water, causing many aquatic products, including fish and shellfish, to suffocate and die, causing serious economic losses
.

High temperatures can also exacerbate water evaporation, causing the salinity of rivers, lakes and seawater to rise
.
Once the salinity in the water exceeds the range that the water produces can bear, they may become sick or even die
.

High temperature will also accelerate the reproduction rate of various pathogens, and at the same time, the immunity of aquatic products will decrease, endangering the life safety
of aquatic products.

"High temperature weather is a problem
that contemporary aquaculture must face.
" Xu Gangchun further said, "At present, the cultivation of aquatic plants and other methods are commonly used in aquaculture to cope with high temperatures, and they have supported the 'umbrella'
for aquaculture.
”

Aquatic plants, can be described as anti-high temperature "artifact", on the one hand through photosynthesis to provide more sufficient dissolved oxygen in water, on the other hand for water products to shade
.
"In general, breeding ponds with aquatic products such as hairy crabs are usually planted in them due to their shallow water depth; In breeding ponds where fish and other aquatic products are raised, due to their deep water depth, floating aquatic grasses such as hollow lotus grass and hollow cabbage are usually planted in them
.
Xu Gangchun said
.