Crab culture

Yangcheng Lake hairy crabs fence crab technical methods
&Nbsp;   fence of Kunshan yangcheng lake crabs can be traced back to the middle of the last century 80 's, due to the lock, dam, blocked the crab migration routes such as Duan, natural water could hardly see any trace of the hairy crabs in yangcheng Lake, part innovation on the basis of the purse seine fishermen fish, began trying to fence the crab. At that time, no more than 800 acres, to the beginning of this century has reached more than 25,000 acres. With the improvement of farming techniques, aquaculture production from the initial yield of 10 kg or so, gradually increased to 40 kg now, economic benefits can be achieved net income of more than 5000 Yuan per MU. Purse seine crabs become major sources of income of local fishermen. Fence crab are different from the fence but the fish, it has a complete set of technical ways: selection waters-purse-seine sets – planting aquatic plants – choose the seeds one by one disinfection stocking one by one management--the fishing market. Some links above, the loops are all linked, are indispensable.

    , select water

   basis for successful choices of water area are crab, crab requirements for water quality is quite high, therefore to select the clear water, transparent 60 cm or more, can easily see the bottom growth of aquatic plants, water slowly, a depth of 1. About 2 m, sediment soils are loam, rigid and flat, no waves, no deep ditch, mud less than 15 cm, must also meet the following physical and chemical and biological indicators:

     (a) the physical and chemical index

     crabs optimum temperature for growth of 25-28, 5 mg/l or more of dissolved oxygen, PH7. 5 8. 5, 0 ammonia nitrogen. 1 mg/liter, organic oxygen (COD) of less than 6 mg/l.

     (b) bio-indicators

     to "grass Lake" is the best aquatic vascular plants there are many different types of grasses grow, plankton and benthos in quantity and variety, hard water, the color of light, usually blue or green.

      second, the purse-seine sets

yangcheng Lake fence culture area of 30 50 acres, a rectangular or square shape.

     (a) fencing materials

     mesh material is polyethylene 12 8th or 9th, anti-enclosure net for 6 6th, mesh. Fence bamboo 20 25 cm in diameter, straight bars, even without damage. Make piles with diameter of 6-7 cm bamboo, clamp 6-7 m long bamboo and bamboo shoots, pressing stone cage made with 246 stones, and bamboo, plastic wire, rope, wire, and other supporting materials.

   (b) fence construction

   General in end of or next year January for piling, and block network, pile from 1 meters, network of bottom with main stone cage fixed, stone cage diameter lO 12 cm, fill stone cannot too full, master in 70% a 80% for good, easy laying, makes network feet and end of mud close, to prevent main stone cage damaged, in main stone cage inside 50 cm at laying Deputy stone cage, diameter 5-6 cm, to River

crab flight. NET upper high out of the water of l_1. 5 meters, too low to prevent flood and was flooding. Set the back cover at the top of the fence mesh (escape-proof net), 50 cm wide, inward and downward tilt angle to 45. In case of crabs crawled out from the Internet. Attention when setting NET bamboo pile connections and do a little loose, not too tight, otherwise susceptible to wind damage NET. Purse seine after all the set up, should be put up outside the fence edges round cage nets, through routine inspections, grasp crabs escape.

     third, planting aquatic plants

     the number of plants within the fence is not only affecting crab recapture rate, market size and quality, but also fencing yangcheng lake crabs the sustainable development of the whole industrial chain. Yu saying "crab size, water; how many crabs, grass" is a very visual metaphor. In order to protect the aquatic resources of yangcheng Lake, on the one hand be sure to protect the grass outside the fence, rational development and utilization on the other, must be planted in the pond water. Fishing professional before planting grass grid in addition to wild, then according to the different varieties of different growing methods.

     (a) bitter grass

     first will network tablets will network surrounding split, half water stocking crab species, half water planting bitter grass, bitter grass General in Tomb before and after water temperature rebounded to 15 ℃ above Shi sowing, select sunny shaizhong 1-2 days, then with mill crushed Hou soaking 12 hours, fishing out Hou rub out fruit within of seed, and cleaning off seed Shang of mucus, again with half dry half wet of fine soil or sand mix species full pool sow. After rubbing the fruit is Lake sub people, grass seed per acre, it normally takes about 100 grams, and grass grows to 20 cm above, removing the separated mesh, the crab into the water area.

   (b) planted Elodea nuttallii

   water temperature 5 ℃ above can be planted, cut into 30-40 cm long stems of Elodea nuttallii, Mud wrap at one end, directly into the water, spacing about 1 meter, Elodea nuttallii multiply very fast, has now become the main planting varieties.

   (c) wheels Ye Heizao plant

   by spore sowing method, polyethylene mesh before planting spores separated from crab, using 50 g per acre, mixed with sand scattered when the water temperature rises to 15 ℃, 51 lO days begin to sprout, emergence rate of up to 90%, when spores grow into lush and remove netting.

    four, purchase seed

   fishery proverbs "three minutes, seven in charge of" crab species directly affect breeding success. Select crab first crab breeding sites studied, how big is the size and origin of crab, operation specifications, in determining the source of crabs when using the method of inquiry and back, crab has been the original and breeding, keeping the Yangtze River some of the characteristics of Eriocheir sinensis, disease resistance, resistance is strong. Choose wild broodstock breeding, actions implemented in natural selection, cleaning to stay pure, bad saving good, maintain strict screening. Then by selected of buckle crab requirements specifications neatly, size 100 only/kg above, physique robust, crawling agile, attached limb complete, limb section no injury, no parasites attached, last to strictly pick out green crab (commonly known as Yao head crab), green crab and yellow crab (buckle crab) of difference is: yellow crab of back methyl for soil yellow, green crab for green color or yellow green; orpiment crab abdominal is triangle, cannot cover head chest methyl abdominal surface, abdominal umbilical around and the attached limb bristles short and dilute, female Green Crab has great, abdominal is oval, can cover head chest methyl abdominal surface, Bristles long and key; realgar crab River foot fluff and the step foot bristles are short and dilute, handover device hose-like, not ossification, and male Green Crab fluff dense, bristles rough long, handover device hard, for bone of tube-like real; open head chest methyl, yellow crab orange color liver obviously, see not to gonad, and green crab female of ovarian for 2 article purple Strip real, male of fine nest for 2 article white block real.

    five, disinfection stocking

     fence yangcheng Lake crab crab species are generally local crab species, transportation by car or boat for a short time, the stocking should take into account the following factors:

     (a) stocking time

     2-March stock this low temperature, crab activity is not strong, not easy to escape, damage and early stocking, early adaptation, early growth can be achieved. To select fine morning when the stocking, crab automobile short distance transport (BU 2 hours) until after the yangcheng Lake, and boat transport to the fence culture

area, or direct speedboat transfer.

   (b) crab of disinfection

   crab species of the local short transport times, types and Miao Fukang 10-15 mg/l of potassium permanganate soak before 2 3, BU 2 minutes at a time, kill the pathogen of crab body, increase immunity and improve the survival rate. Field transport long crab crab species or species, can supervise cultivation in stocking a week before using a pesticide, disinfectant, stocking just before Miao Fukang 10-15 mg/l for 5 minutes.

   (c) stocking density

   under water in the natural food, costs and expected sales to determine stocking density. Abundant natural food (clam-screw, lush), it may be appropriate to increase the amount of stock and high cost of farming (feed, seed prices), and expected lower sales prices, it may be appropriate to reduce the amount of stock. Fence per acre stocked yangcheng Lake 350 4 (), 0, a full release.

    six, feed feed

   (a) food variety

     bait can be divided into plant food, animal feed and artificial diet. J plant feed: natural grass, artificial feeding of corn, wheat, soy beans, squash and other animal feed: natural snail shell, enough can put snails per acre before the Tomb-200~300 kilograms, artificial feeding of the fish from this Lake District (chuantiao, abalone, carp, wheat). Artificial diet are based on nutritional requirement standard artificial crab from the preparation of the full price of special diets.

    (b) the feeding to

    fence culture hairy stocking crab species feeding amount should be based on quantity, weight and cast the bait of the variety, quality, feed coefficient and total output is expected to develop years of feeding, climatic conditions, the water temperature in the base area, in accordance with the annual amount of feeding make monthly feeding plan. 4-October is feeding season for crabs, particularly in September, after crabs molt one last time, feeding intensity maximum. General feeding feeding in the first half of the total annual amount of feeding 350/0 40~/0,7-10 month 600/0-65~/0 of the total annual amount of feeding, the amount of feeding according to the weight of the crab, save crab feed in the early 10% of the 15%, later fed to save crabs 5% a 10% of the total, and under the weather, water temperature, water quality and eating hairy crabs flexible, reasonable adjustments. While water quantity is stable in the purse-seine and judge the rationality of the diets fed an important indicator.

   (c) feeding method

   fed 2 times a day, once in the 6 o'clock in the morning and 17 o'clock in the afternoon, feeding all day 1/3 and 2/3 respectively. Cooked corn, wheat, soybeans and other feed. Breed early, with the taste of animal feed and feed plants and, to speed up the recovery of crab species physical medium term mainly plant food; later fed animal feed, so that "two fine, thick in the middle." Specific feed to do "four" and "four"    "four": a certain quality, variety of animal food should be fresh, not decay,

quality, feeding cannot monotone, chunks of and has shell of feed to cut broken, and smashed; II quantitative, fishing proverbs said of good, "day not feed, three days not long", despite crabs has resistance hunger of skills, but if let crabs hunger full excesses, has food on feed, no food on strike, not let it eat full, on long of slow, adverse shed shell, and growth individual small, daily feeding to night eat finished for degrees; three timing, crabs day often hidden Yu dark and grass district, to night or shimmer Xia only out activities foraging, Therefore fixed at 6 o'clock in the morning 17 o'clock in the evening every day feeding with feed four position, each fed with diets are presented in a fixed location, enabling foraging for crabs to grow and provide the basis for checking feeding conditions and develop a feeding plan.

   "four": a look at the season, cold weather in early spring, crabs food consumption low, choose sunny evening feeding, water temperature is gradually increased after the Tomb, you can slowly increase the amount of feeding, keeping uniform feed palatability. Summer water temperature over 30 ℃, stop feeding, Lu Hou, crab appetite strong, can increased voted bait volume; II see weather, fine more feeding, rainy, and hot, and no wind to rain less feed, storm stopped feed, rain Hou fine can more feed; three see grass growth situation, grass reduced, to increased feeding volume, grass had key, to reduced feeding volume; four see crabs feeding situation, daily sooner or later to tour Lake check bait and feeding situation, as voted bait Hou soon eat finished, crabs activities normal, is should appropriate increased voted bait volume, If the day after feeding at night is not finished, or found the sick crab, Dead crabs, should reduce the amount of bait.

    (a) aquatic weed management

    seven, and management I     to regularly check the growth of aquatic plants, if too small, in June, transplanted from other lakes aquatic weeds, if too much, in mid-July summer culture of grass carp fingerlings to biological control of aquatic weeds grow, raising per acre 10-20, Elodea nuttallii heat, their heads should be cut during the summer, leaving only 10 cm above the root left

the right to prevent their deaths.

     (b) the escape-proof facilities management

     check the fence every day, the main view outside the fence around the crab that cage net outflows, and escaped, taking timely measures. A small check for three days, mainly solid checking fences, damaged. Seven-day El Chaco, mainly view the stone cage are attached or suspended. Especially in flood season and typhoon season, to step up patrol checks, timely heightening and consolidation of facilities, find the problem resolved in a timely manner to prevent the crabs escape.

     (c) morning and evening patrols to prevent theft

     adhere to the morning and evening patrols observed changes in water temperature, water quality during the day, evening and night-time observation of crabs activities, mainly food, in order to adjust management measures. In the crab season to step up care, step up patrols, escape-proof carefully to prevent occurrence of theft.

     listed eight, fishing

after several months of careful breeding, basically reach sexual maturity until the end of September hairy crabs, fishing listed at this time. Yangcheng lake crabs of fishing method main has four species: a is mihunzhen (and called crab Duan) capture, it has network wall for Guide network, induced crabs into bag in the, bag has 710 section, long 10 meters around, imports big, export small, is round or square, sank into Lake end of, imports at Qian several section each section are has loft pour network, can into cannot out. Bag fixed in network wall of trumpet at, sooner or later the once, pour out bag in the of crabs; II is to cage network capture, it is a hidden of catching crab tool, sank people Lake end of, above for good mark, long 10 meters to dozens of meters ranging, has many section, is rectangular, each section has entrance, can into cannot out, several section has a crab bags, each acres set 2~3 article, daily sooner or later as long as pour out, tied good bags mouth put back in situ; three is thorn network capture, thorn network more for nylon made (fishermen called screen), each article long 50 meters, high 1 meters around, Placed vertically in water lower, net floats, floating in the water, the crabs in the water activity is achieved by winding capture focus four manual capture, which is direct from the escape arrest anti-cover the Internet.

   hairy crabs on sale can be carried out through various channels: first, early farmers in accordance with orders by foreign trade company, this way the maximum

advantage is price stability and, secondly, when the crab fat yellow, directly on to crab market

market, which is flexible, but price fluctuations, the stakes are large;

third, the last specification, the grade of crab culture in crab in boxes or cages,

sale prices go up again, locals call it hoarding crab in this way.

     crabs in sales process in the, according to its habit specifications into sanliujiudeng, first crab (local said special foreign trade crab) specifications female crab 175 grams above, male crab 250 grams above; II, crab (local said foreign trade crab) specifications female crab 150 grams above, male crab 200 grams above; grid female crab 125 grid also different, three, crab (local called wipe tablets) rules 1145 grams, male crab 175-195 grams. Different grades, their price and the large gap. Renowned at home and abroad with the yangcheng Lake hairy crabs, crab ponds have also been developing rapidly in Kunshan, 2008 area over 80000 acres. Currently Kunshan pond raised crab method main used crab shrimp polyculture way, buckle crab acres put 600 only around, shrimp seedlings species acres put 30000 tail, appropriate sets raised some silver Bighead carp fish, and fence raised crab as, pond raised crab also to set anti-escape facilities, main material for aluminum Board or calcium plastic Board, will pond around live, put species Qian pond first with health lime each acres l 0 kg for disinfection, 15 days Hou injection 50 cm, stacked basal foster natural bait. ~4 month plant Elodea nuttallii, turn Ye Heizao in early February, and bitter grass, cover 50%~60%, before Ching Ming put snails 300 kg per acre, usually in addition to feeding and disease management, with particular emphasis on water quality regulation, improved sediment environment so as to achieve the goal of ecological, healthy breeding, a solid technical base for environment-friendly fishery development.

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