'^qp aan ao 2 ndm 2006 17
'\7em xanh Id loai nhiem the y hai manh vd, sdng d cdc viing ven bien, ven dao cd ten khoa hoc Id Pernaviridis (Linne,
1758). Chiing thupc nhdm dn Ipc, thifc dn Ua thich Id thucvqt phii du vd cdc clidt hihi ca la lirng.
Vem vd xanh la ddng vat bien than mem thit tham ngon, cd him lugng dinh dudng cao, vd cd ting nggc day duge diing de che bie'n mdt sd hang thii cdng my nghe, trang tri dd dimg nhu kham xa cir ban ghe, Ig hoa vi nhieu mat hing khac.
Hien nay cd hai hinh thiic nudi vem vd xanh: nudi day treo va nudi day quin tren cgc.
Nudi day treo la hinh thiic treo cic diy cd vem bam vio be hoac gian d ngoai bien.
Nudi quan cgc la dung day cd vem bim quan xung quanh cgc ddng CO dinh d bai trieu. Hai hinh thirc nudi cd nhirng cdng doan chinh sau diy.
Chon diem nuoi
Du nudi diy treo hay qui'n day trdn cgc, dia didm nudi deu phai cd cac dieu kien sau:
KY THUAT NUOI
VEM X A N H
- Day treo bing nildng dudng kinh nhd ban day vem bam, dai 1 - 1,5m, mdt diu ludn qua khuyd't budc chat, diu kia de budc vao gian treo hoac be.
- Gian treo gdm 4 hoac 6, 8 cgc tuy theo dien tich gian nudi. Cic cgc lam bing gd tdt, chiu duge nudc man, mdi cgc dii tir 2 - 2,5m dudng kinh 10 - 15cm ddng thing diing theo chidu vudng gdc vdi ddng chiy cua nudc. Mdi cgc ddng cich deu nhau 1,5 -2m. Xi lam bing gd trdn dudng kinh 10 cm, xa dgc dai 1,6 - 2m, xa ngang dai tuy theo chieu dii cua giin nudi. Cic x i lien ket vdi dau cgc bing mdi budc day thep dudng kinh 2 - 2,5mm, mdi xa each ddu nhau 0,8m.
Nudi ddy qudn cpe, gdm cdc bp phdn:
- Ming chiia vem gid'ng lam bing xi mang lang nhin hoac bing nhya hay ghep bing gd lot nildng de giir duge nudc.
Ming hinh thang day dudi rdng 0,5m, thanh ming cao 0,5m.
- Diy cho vem ban lam bing be dira hoac soi cdi (ben nhu day thimg, chao) dudng kinh cua day 1,5 - 2 cm, dii 2-3cm.
Theo kinh nghiem dung diy bing be dira hoac cdi mem dd - Noi cd do siu thich hgp tir
- 0,5m xudng - I m so vdi mat 0 hai dd (mat nudc d miic thuy tridu rdng nhat cd the xiy ra) hoac tir tuyen ha trieu de'n sau tren 10m nudc.
- Nudc bien cd do man tir 18 %o den 32 %o thich hgp nhit la 20 %o de'n 30 %o va do trong cira nudc bien tir 2m trd len.
- Ddng chay ciia nudc tir 0,2 m / s - 0 , 5 m/s.
Vat lieu va cau tao cac bg phan nuoi vem
Nudi day treo, gdm cic bd phan:
- Tlii chira gid'ng lam bing vai man hoac ludi eudc sgi min cd mat ludi mau hay bing nildng. Theo kinh nghiem, dung tui bing nildng tran bdng dd quan sit, song phai due cac Id quanh tiii cd dudng kinh 2 - 3mm de nudc bien cd thd vao tlii. Tlii dai 30 - 40cm, dudng kinh tlii la 4 - 5cm.
- Day cho vem bam lam bing sgi nildng dudng kinh 2- 3cm dai 50cm, mdt diu budc
thanh khuyd't de ludn diy treo. quan vao cgc.
KHOA HOC VA CONG NGHE NAM DINH Sd 1A - Trdn Te XiJdng - TP N a m Dinh
18 c7a/i axui ao 2 ndm 2006
- Cgc dd quan day nudi vem lam bing gd khd, chiu duge nudc man (khdng dung gd cd nhira ding, ddc va cd nhua tuoi). Cgc dai 2 - 2,5 m, dudng kinh 10 - 1 5 cm, ddng sau xud'ng nudc tir 0,5m trd len dd sdng vd khdng do cgc.
Ky thuat nuoi.
- Tao gid'ng bam vao diy:
+ Dd'i vdi day treo tien hanh nhu sau: Ludn day qua tiii, budc chat mdt dau day vio mdt diu tiii tha vem vao tiii. Mdi tiii cd the tha tir 1000 - 1500 con vem cd 0,5 - 1 cm sau dd budc chat diu tui thii hai, dem tiii treo vao gian nudi, dat ngap nudc.
Sau 5-10 ngay quan sat tha'y hau het vem da bim vio day thi cit bd tlii. Diing keo cit tia bdt nhung con vem bam d chd diy. To chan cua vem bim rit chic va dai nhu cao su, theo kinh nghiem khdng the dung tay diit vem ra khdi day, ndu lam manh rudt vem se tudt khdi
vd. Nhirng con vem duge cit to chin duge dirng cho vao tiii bam d day sau. Dem diy cd vem bam treo vao gian nudi.
-I- Dd'i vdi diy quin cgc, tie'n hanh nhu sau: Dua nudc bien vao mang (nude bidn cd do man tuong duong vdi do man d noi nudi vem), cho sue khi va rai vem vao ming, tuy theo chieu dii ciia day ma quye't dinh sd lugng vem gid'ng. Dat day vao mang theo chieu dgc cua mang, day nim giira ldp vem gid'ng.
Sau 3 den 5 ngay quan sat tha'y hiu het vem trong mang da bim vao diy. Dem day ra khdi mang tia bdt nhimg chd vem bim diy, dem day quan vio cgc de nudi. Mdi cgc cd the quan tir 1-2 day
- Chdm sdc:
+ Thudng xuydn kidm tra gian treo, cgc va day dd kip thdi tu sita khi cd sir cd.
-f Ludn ludn lam ve sinh day treo, edt vi day de han che con
ha, con sun bam lam diit day va kiem tra ca, ghe vio an thit vem. Td't nhat xung quanh gian nudi hoac cgc nudi cang them ludi de chd'ng ca, cua ghe vao an thit vem.
Nudi vem d ao dim nudi tdm can chii y: Chu ky nudi tdm ngin (khoang 4 - 5 thing/vu), trong khi chu ky nudi vem dai hon. Do dd trudc khi thu hoach tdm phai bd tri mdt ao dam co du didu kien de di ddi vem sang nudi tam, cho de'n khi nudi tdm vii 2, dem vem trd lai nudi.
Thu hoach vem
Vem la loai sinh trudng cham, sau 1,5 - 2 nam vem mdi dat cd 80-100 mm chieu dai.
Nudi vem dat de'n cd thuang pham cung phai sau 1-1,5 nam mdi thu hoach. Cich tie'n hanh nhu sau: Dung dao hoac keo cit chan to eua timg ca the, khdng diing tay diirt.
Bien tap: Hiiru Nam Ngudn KH&DS
c^ diijE
Mot ong chong nghi ba vg minh bj lang tai ben quyet djnh thu nghiem. Ong chong khe khang dung sau lung ba khoang muoi met va gpi:
- "Minh oi! Minh co nghe ro khong?"
Ba vg khdng tra ldi, the la dng chong ben tien tdi gan khoang each sau met roi lai gpi:
- "Minh oi! Minh co nghe khong?"
Ba vp van chang ir hu. Ong chong ben di den chd each ba con ba met hdi:
- "Minh khong nghe gi het ha?"
Ba vp dap:
"Co chu! Lan nay em tra Idi la lan thu ba roi day!".
KHOA HOC VA CONG NGHE NAM D|NH Sd 1A - Trdn Te X a d n g - TP N a m Djnh
