KHOA HOC C 6 H G NGHE
M^EHlElM CLTU MOT S D OAC OlEHi 5II\IH HOC C U A - CA l\IBIJA XAM (TOR TAMBROEDES /BLEEKER, 1 9 ^ 4 ) )
TAI TAY IXIGUYEIM .^^^
Phan Dmh PhucS Duong T i t a o ^ u o n g ^ T 6 M T A T BV BD Tir t h i n g 11/2013 d i n thang 8/2014 da Uen hanh thu 72 mdu ca ngua icam tii cac huyen Buon Don t i a l ^ % Ldk, huy^n Cu Jut tinh Ddk Nong va huyen Lam Ha tinh Lam Dong de tien hanh nghien ciiu mot sg^ifl^
di^m sinh hpc cua cd ngua xam. K^t qua cho tbay mdt sd chi tifiu phan Ioai deu phii hpp vdi mifiu ta ciia cac tac gia trudc day. Cu the vay lung la 4 / 9 , vay nguc: 1/15, vay bung: 1/8, vdy hSu mdn: 3 / 5 , sd vay dudnll Sen dao dpng 22 - 24; sd lop vay h a n g ngang: 4,1,2. Chilu dM than trung binh gap 5,20 lan chilu dai ddu. Child dai ru6t trung binb gdp 1,73 ldn c h i l u dai than. Nghifin cuu thuc an Uong niot ca cho thay day la loai an ts^
tiufin v l ddng v a t Mdi tuong quan giua chilu dai va khdi luong ca kha chat che (R^ = 0,904) duoc bilu difin bdng phuang trinh W = 0,01*L^'^. Ca hai do bfio Futton va Clark d i u tang cao nhat vao tiiang 12 (Fulton
=2,47 va Clark = 2,35) v a t i i a p n h a t v a o thang 11 (Fulton = 1,95 va Clark = 1,82). Siic sinh san tuyet d di ndm frong khoang 3.474-7.842 t n i n g / c a t h i , siic sinh san tirong ddi 8,1-9,7 t n h i g / g ca cai.
Tii khda: Tor tambroides, chilu dai rudt, do beo, sue sinh san tmmg ddi, siic sinh san tuyfit ddi.
I.IWflAU
Cd N g u a x d m Tor tambroides ( B l e e k e r , 1854) t h u p c h p c d c h e p C y p r i n i d a e , p h a n h p c d b d n g Barbinae, g i d n g c a n g u a g a i T o r Gray, 1833. C h o d i n nay cd t h i cd n g u a x d m cd c h i e u ddi l d n n h a t d u p c g h i nh&n d luu v y c Mfi K d n g tai Lao la 100 c m (Baird etal., 1999). Cd n g u a x d m t n r d n g t h a n h s d n g d s d n g , sudi ed d a y la edt, s d i h a y d a cuoi c h a y q u a n h i i n g k h u rirng. C a n g u a x d m c o n t h u d n g g a p d n h u n g n o i cd n h i l u g h l n h t h d c , c h u n g c d x u h u d n g n g u p c lfin t h u o n g n g u d n s a u k h i n d . S i n h s a n n h a n t a o e a n g u a xdm c u n g d u p c nghifin ciru t h a n h c d n g d Malaysia k h i sii d u n g cd d u e c d k h d i l u p n g t r o n g k h o a n g 0,7 - 3,9 k g vd ed cdi Id 2,5 - 2 1 k g ( h i g r a m et al., 2007).
Cd ngua x d m c d thit t h o m n g o n , g i d tri k i n h t e c a o , dupc thi t r u d n g r a t u a c h u p n g . Hifin n a y d o k h a i t h d c qud miic nfin loai n d y g i a m siit c a v l s a n l u p n g v a khdi l u p n g c u a c a t h e t r o n g q u a n d d n tai T a y N g u y e n (Dy ^ Q u a n l y n g h i c d l u u v u e s d n g Mfi K d n g , 2005). Vi v a y vific nghifin ciiu m d t s d d a e d i l m sinh h p c ldm CO s d c h o vific t h u a n h d a v a k h a i t h d e n g u d n gien cd n g u a x d m Id vific l d m h e t siic c d n t h i e t v a ciing la m y c tifiu c u a nghifin ciiu nay.
2. NGUY6H VAI I B l VA PHIIONG PHAP NGHBU CUU 2.1. D d i t u p n g , tiidi g i a n vd dia d i l m nghifin ciiu
* Ddi tupng nghidn cuu: Ca ngua xdm Tor tambroides (^Xeeker, 1954).
Vi?n Nghien cihi Nuoi trdng Thiiy san IU
N 5 N G NGHIEP VA PHAT TRIEN NONG THON
* Thdi gian vi dia diem nghien cuu. Da tien hdnh thu mdu tai cdc huyfin Budn Ddn tinh Dak Ldk, huyfin Cu Jut tinh Ddk Ndng va huyfin Lam Ha linh Lam Ddng tir tiiang 11/2013 den tiidng 8/2014.
2.2. Nghifin ciiu dac dilm smh trudng
* Xic dinh tirong quan chiSu dii vi khdi Iupng ci thdng qua cong thuc:
W = a * L ' '
Trong dd: W: khdi Iupng; L: chiiu dii; a : hing sd; b: sd md (Pham Thanh Uem va Trdn Dde Dinh, 2004).
*Xic dinh tudi ca
Dung vay d l xac dinh tudi ca ngua xam. Mdu vay dupc ngam trong dung dich NaOH 4% d l tdy md, cac chat ban hay sdc td bdm tifin vay. Tiln hdnh quan sat cae vdng ddng tam due vd trong sudt ndm hfin tiep nhau tren vay ca, ranh gidi giua cac viing due va trong cho phep xdc dinh vdng tudi cd theo nam. Viee quan sat true tilp bdng kinh hien vi (Pham TTianh Lifim va Tran Dde Dinh, 2004).
*Xac dinh he sdbeo Xae dinh dd beo cua cd theo:
+ Cdng thuc Fulton (1902): Q = W x 100/L,^
+ Cdng tiiuc Clark (1928): Q^ = WQX 100/ U Trong do: Q vd Qo la dp beo Fulton vd Clark; W Id khdi lupng toan than ea (g); W,, Id khdi lupng todn than ca da hd ndi quan (g); U la chifiu ddi tifiu chuan (cm) (Nguyfin van Triiu e^a/. 2006).
KY2-THANG 10/2014 87
2.3. Phuong p h ^ nghifin ctiu v l dac dilm dmh
* Thu miu vi cd dinh miu
Mdu cd dupc xdc dinh chieu dai va khdi lupng co thi, chieu dai va khdi lupng he thdng tifiu hoa. Giai phdu ca va he thdng tifiu hod se dupc ngam vao fomahn 7%, sau dd mang ve phdng thi nghiem phan tich cac loai thuc an cd trong he thdng tifiu hod.
*Hd sdgida chieu dii rupt va chiiu dai thin Chi sd tuong quan chieu ddi rudt vd chilu dai than dugc xac dinh theo Nikolsky (1963).
Chieu dai rudt RLG=
Chilu dai l^ng cdng
(RLG; Relative length of the gut- chilu ddi rudt can ddi)
* Xac dinh thinh phin thuc an bing phuong phip tan sd xuat hien
Trong phirong phdp ndy sd luong he thdng tieu hda ca hifin difin tung loai tinic an rieng biet dupc quy ddi ra phan tram {%) trfin tdng sd he thdng tifiu hda dupc quan sat (Hynes, 1950). Phuong phdp ndy dupc tien hdnh theo 2 hudc.
Budc 1: Tat ea ede loai thiic an hien dien trong cdc mdu quan sat se duoc het ke thanh mdt danh sach, sau dd sir hifin difin hay khdng cd mat cua mdi loai thiic an se duoc ghi nhdn lai.
Budc 2: Sd lupng hfi thdng tieu hda trong do cd su hifin difin ciia mdi loai thiic an se dupc cdng lal va each tinh tuong tir cho cac loai thiic an cdn lai, sau dd se dupc tinh ra phan tram tren sd mdu quan sat (Pham Thanh Lifim va Trdn Dac Dinh, 2004).
* Xic dinh thinh phan thuc in bang phuong phip udc Iupng bing mit (phuong phap thd tich)
Trong phuong phdp nay, thiie an ti-ong mdi mdu rudt ca dupc dua vfi cung mdt don vi the tich va mdi loai thiic an dugc tmh ra theo phan tram the tich.
Thiic an tiong mdi mpt ca cho vdo the tieh nudc nhat dinh, ldc that manh d l thiie an phan tan deu trong nudc. Sau dd cho vdo budng dim 1 gigt nudc mdu va quan sat tifin kinh hien vi. Difin tieh hi chilm bdi mdi loai thiic an dugc xdc dinh theo don vi da quy udc.
Mdi mdu rupt ca quan sdt it nhat 10 gipt, sau dd lay gia tri tiling hinh eho mdi loai thuc an (Pham Thanh Lifim va Trdn Ddc Dinh, 2004).
2.4. Nghien ciiu v l d ^ dilm smh san Thu mdu cd ngua xam b cac sdng va thuy vuc trong tmh Dak Lak de xdc dinh sue smh san, cac gia|
doan phat hien cua tuyin sinh due due va cai. Tiqr&
sinh due se dugc cat lat va chup anh cac giai doan phat trien khdc nhau.
*J^c dinh hinh thai cdu tao tuy&i sinh due "
D l xdc dinh hinh thai va giai doan phat trien oia tuyen sinh due ca ngua xam, tien hanh quan sat hinh thai tuyin sinh due hang mat thudng vd kinh lup theo thang 6 giai doan cuaXakun va Buskaia (1968).
*^c dfnh mo va tebao tuyen sinh due Mdu dinh hmh trong dung dich Bovm, sau dd xii ly tiieo phuong phap nghifin ciiu td chiic hoc thdng thudng. Tmh sao nhudm man theo phuang phdp Hematoxylin - Sat cua Heidenhai va budng tnrng nhudm mau theo phuong phap Hematoxylin - Eozin cua Heidenhai. Dgc tieu ban theo hudng din ciia Xakun va Buskaia (1968) dudi kinh hiln vi.
*Xac dinh sdc smh san tuydt ddi vi tuong ddi Tuyen sinh due cdi thanh thuc feiai doan IV-V) duoc thu thap, can khdi Iugng hudng tning vd lay mdu d 3 viing khde rtiiau vd can khdi lupng mSu bang can dien tii cd dp chinh xdc tdi 0,001 g. D i m sd lupi^
tning cua mdu udc tinh sd lupng tning eiia tuyin sinh due cai. Tu dd tinh cac siic sinh san theo nhung cdng thiic sau:
- Sue sinh san tuydt ddi dupc xac dinh theo cdng thuc:
nG F =
g
Trong dd: G: Khdi lupng budng tning; g: Kh^i lupng mdu tning lay ra d l d^m fe); n: Sd tning ciia mdu ldy ra de dim (hat).
- Siic sinh sin tuong ddi dupc xac dinh theo cdag thiic:
Sd tning cd trong hudng tning RF =
Khdi lupng than (g)
(Pham Ttianh Uem va Trdn Dac Dmh, 2004).
3.KEn|UANGHniCUU
3.1. Nghifin ciiu dac dilm phdn loai vd sinb trudng
Bay muoi hai mdu ca ngua xam dugc do d ^ <%
thdng sd ve phan loai va trinh bdy d bang 1.
88 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 10/2014
KHOA HOC CdNG NGHi
3.1.1. Mota
D = 4 3 ; i ^ 3,5; P = 1,15; V=l,8.
U = 22;b-= 4 / 1 / 2 .
Lo = 19,28; H = 5,87; T= 4,78; 0 = 1 , ^ 0 0 = 3 3 . Ca ngua xam co than lliudn dai. d ^ bfin. Dau nho va mdm nhpn. Mifing nho Uidng dai d o i vioi trudc m a t Moi Asy, moi tren c6 I h i ^ tibit ngdn. Moi dudi CO thtQT diit dai hinh vong ctmg dudi mom. Ranh sau moi duoi hen tuc. Rach mioig dai chua d o i m a t Co hai ddi rau, ca cang ldn rau cang dai, doi iau tren dai hon ddi r ^ duoi, rau mom dai hon dudng kinh mdt khoang 1,5 lan, rau ham tren ngdn. Duong ben hodn toan, cong a ^ y nguc. Khoi diem v% hmg gan nhu ddi xizng vay bung. V ^ lung co 9 tia vv^ khong phan nhaidi, goc vay hmg c6 tbd fliit bao boc va nho lfin hoi cao. Waj nguc co 16 tia v ^ . Vay bung co 9 tia khdng xe rang cua. V ^ hau mon co 3 tia v ^ khdng phSn nhanh va 5 ha vay phan nhanh. Y ^ dudi phan thu^ sau, chia 2 nhanh, nhanh trfin cac tia khdng phSn nhanh, nhanh duoi cac tia phin thanh 3 nhanh.
Todn than ca phu vky to, s ^ x ^ deu, can ddL So lop vay dudng ben la 22-24 cai, so ldp vay trfin duong hen Id 7. Dudng bfin phan trudc hoi ldm, phan sau di vao giura cdn duoi. Ca ngua xam c6 2 m i t to. Idioang each giua 2 mat rpng, ddu thon can d6i, idie mang hoi hep. Nhmig md ta v l ca ngua xam cua nghien aiu nay tuong ddng voi nhung md ta trudc do ve loai ndy (Nguyfin Tbi Thu He, 2000; Nguyfin Van Hao va Ngd a van, 2001).
Bang 1: MQt a 6 d n tieo vfi Mnh flrii c m c i SIT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Cac dli sd Qnen dai dian L (cm) Chien dai chuan Lo (cm) Khoi fanmg ca W (g) Chifa dai aau,T (cm) Chien cao IhanH (cm) Sd tia v ^ ngiK P (tia) Qiifa dai vay nguc (cm) Sd tia vay bung V (tia) Chien dai va^ bung (cm) SdtiavaylimgD (tia) Chilu dai vay hmg (cm) Sd tia vay hau mon, A (tia^
Chieu dai vay hau mon, (cm) C3lifa daa v% dudi. C (cm) Sd lop vay hang ngang TT (caO Chieu dai root (cm) Sd lop vay t l ^ ducmg hen Ll Oop)
Tyle dai tfaan/dai dau (lap) Tyle dai mot/dai than 0an)
TB 25.04 19,28 1903 4,78 5.87 145 3,29 1,80 3,08 4J0 3,91 330 4,90 4,33 4 i 2 43,23 22,61 5,20 1,73
±a>
7,26 537 201,09
1,33 1.75 0,00 2,73 0,00 1.44 0,00 146 0,00 2.75 1.43 0.00 12,39 0,67 0,43 0,27
±SE Oft! 0,67 24.04 046 0,21 0;00 033 0,00 0,17 0,00 0,14 0,00 0,33 0.17 0.00 1,48 0,08 0,05 0,03 - Mau s ^ T o a n ifaan ca c6 mau xam den, bung xam n h a t Ca thu m ^ dupc co kich tinioc tii nho d ^ lon. Luc ran nho, than ca cd mau xam bac nhat dan v l phia bung. Goc v ^ a hmg co dai den n h a t Cac vay CO man xam. Khi ck lon c a trfin 500 g tro lfin, ca c6 mau xam bac hoi den, toan ttian co mau xam den.
Kidi cd ldn n h ^ cua ca ngua xam ma ngu dan da danh b i t dugc ndm 2009 tai song Krong No, dia ^ban huyen Lam Ha, tinh Lam Ddng nang 13 kg.
Hinh 1: ThiJEy giOa mdi dudi cua dia 7br/laai&raHfes OQ v i Tixrdbi^
Ghi diii: 1- Tbifygiua dia moi duoi; 2- Duong IK^ kdt cua 2 khoe mieng.
- So sinh. So sdnh cac loai trong gidng thi hmh thdi ngoai ciia Tor tambroides gan gidng voi cac ca thi cua lodi Tor douronensis. Hai kiai nay khac nhau d mdt dilm dfi nh|n thay la thiiy giua mdi dudi cua Tor tambroides kfio ddi va dilm k i t thiic noi vdi hai gdc mi^ng thdnh mdt dudng fliing (\Ki. Con thuy
giiia moi duoi ciia Tordinironaisis tbi ngdn ban nhilu 0 ^ . Ca hai loai nay diu thl^ phan bd a cac thiiy vuc dieu tia. Dac diem khac bifit n ^ cua Tor tamixvides va Tor douronensis hoan toan phii hpp vdi md ta ciia FAO (Flshbase, 2014).
3.1.2. Tmmg quan chieu dai va khdi lupng
N 6 N G NGHIEP V A PHAT IWEN NONG THON - KY 2 - THANG 10/2014 89
Ap dung phuong trinh tuong quan ve chi^u dai va kh6i lugng cua Berverton - Holt (1956) voi nhung so lieu thu duoc va lap duoc phuong tiinh sau:
W - 0 , 0 1 ' 1.200 -|
l.OOO 1 SOO 1 600
n
•* 4 0 0 2 0 0
1
•*
0 2 0
^^
30 Ad C b i e u flai ( c m )
R - = 0.904
50 6 0
Hmh 2: Dd thi h i & diSn tuong quan giua chi^u ddi vd khdi luong ctia ca ngua xdm
Bang 2: Can tnic tudi ciia qudn ddn ca ngua xam
Do tiii bieu difin phuong hinh di^lc trinh bay 6 binh 2 vdi R^ = 0,904 chiing td mdi tuong quan gifla chieu dai vd khdi lucmg la kha. chat che.
Dd thi cdn cho thay ca ngua xam Id lodi cd su tang trudng ve chieu dai ti 1$ thuan voi su tang trudrng vi khdi luorng ciia chiing. Nhu vay cd the noi su tang trudng ve chi^u dai va khdi luong cua ca ngua xdm phii hop vdi qui luat phat triln cua ci xuong viing nhiet ddi ndi chung.
3.1.3. Tudica
Ket qua ph§n tich 72 mau, trong do cac mdu thu chu yeu trong 4 thdng la cac thang 11 vd thdi^
12/2013 (mua khd), thdng 5 va thang 6/2014 (miia mua) duoc trinh hdy b bang 2 vd hmh 3.
Nhom tuoi 0*
1*
2*
3*
4*
Chieu dai L (cm) 1 7 - 2 5 2 5 - 3 5 37-38,4 41,5 - 43,5
49
22,56 28,60 37,90 42,13 49
Khoi luoni
w„„-w„
28,15-220 240-450 490-580 810-780 1.100
r-w(g)
114,10
w„„
267,50 546,67 792,50 1,100
MSu thu S^ luong
58 6 3 4 1
80.56
%
8.33 4.17 5.56 1.39
3.1.4. He sdbeo
Dd beo the hien muc do tich luy dinh dudng cua cd vd thay ddi theo timg giai doan phdt tnen cua co the. Dac biet do beo thay doi theo su phat tii^n cua tuyen sinh due va cd y nghia quan trong trong vi6c du doan thdi gian de trung cua cd. He sd beo cang
b: Vdng sinh trudng c; Kich thudc vdng nam thii nhdt Hinh 3: Hinh thdi vay va vdng nam
cao thi thdi gian de tnmg cang gan (Paradm, 1963).
Hinh 4 cho thay ca hai do beo Futton vd Clark d ^ cao nhat vdo thang 12 (Fulton =2,47 vd Clark = 2 ; ^ ke den la thdng 6 (Fulton = 2,19 va Clark = 2 , 0 4 ^ , ti^p theo la thang 5. Cd hai do beo deu thap nhat Wo tiiang 11 (Fulton = 1,95 va Clark = 1,82).
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 10/20W
KHOA HOC CdNG NGHi
- • ' 1
« 2.5 •
^ 2,1 I ^ 1.7
_ -•-FnlKm -•-Clad:
11 1 2 5 6 Thai^
3.2. N ^ ^ ctiu d ^ ^im dinh duong 3.2.1. He sd chieu diiruotvi chieu dai thin Mdt he sd thudng dupc dung de xdc djnh tinh an ctia cd la chi sd tuong quan gitia chidu dai mot ca va chieu ddi than. Tlieo Alikunhi va Eao (1951), Pham Phuong Loan, (2006), chieu ddi mot cdc loai ca phu thudc vao loai thiic an tu nhifin md chiing ti^u thu.
Chi^u ddi mot tang tiieo su gia tang t^ 1§ cdc loai thiic an thuc vat trong khau phdn an cua cd.
Hmh 4: Dd beo Fulton vd dd bdo Clack
Bang 3: Tiiong guan c h i ^ ddi mpt v^ c h i ^ ddi than (RLG) Chiatu do
C h i ^ u dM t o a n t h a n ( c m ) Chi^u d a i r u o t (cm)
T u o n g q u a n giiia c h i e u d a i r u o t v a c h i ^ u dai t o a n t h a n (RLG)
T n m g b i n h 25,09 ± 7 , 2 7 43,23 ± 1 2 , 3 9
1,73 ± 0 , 2 8 M i n 16,70
17,0 0,03
M a x 60,0 17,0 1,00 Cd ngua xdm la loai khdng cd da ddy. Kdt qua
nghifin ciiu tu bang tren cho thay su tuong quan giiia chi^u ddi mdt vd chieu ddi than ca ngua xdm RLG (Relative length of the gut) la 1,73. Hieo nhdn dinh Nikolsky (1963), nhiing lodi cd cd tinh an thifin ve ddng vdt se cd gia tri Li/Lo < 1, ca an tap cd Li/Lo = 1-3 vd cd an thifin ve thuc vat Li/Lo > 3. Khi ddi chi^u k^t qua nghien cihi b bdng 3 RLG = 1,73 cd th^
k^t luSn rdng cd ngua xdm thudc loai an tap.
3.2.2. Thuc in tu nhidn cua ci ngua xim
* Tan sd bat gip cic Ioai thuc in tiong he thdng tidu hda cua ci ngua xim
Phuong phap ndy tinh tan sd xuat hien hdng cdeh xdc dinh cdc logi thiic an hien difin trong hfi thdng tifiu hda ca. Phuong phdp nay cho phep dinh tinh thdnh phan thiic an vd tdn sd xuat hifin cua mdi I091 thiic an trong sd mdu quan sat, giiip suy doan dufjc tinh lua chpn Ihiic an cua cd ngua xdm.
Bdng 4: Tdn sd xuat hi§n tfaiic Sn trong hfi ihdng tifiu hda cua cd ngua xdm
thdng tifiu hda ciia cd ngua xdm, tan sd xuat hifin cua ddng vat khdng xuong sdng cao nhdt, chiem 70%, den mun ha huu co (60%), ddng vat nguyen sinh (40%), tao luc (35%), ddng vat cd xuong sdng (30%) va nganh tao ldng roi lech (30%). Nhu vay tir dd suy ra ca ngua xam cd thien hudng an ddng vat
* Phd thuc in cua ci ngua xim theo phuang phip the tich
Tiianh phdn cdc loai thuc Sn cd ngua xam trong hfi thdng tieu hda phan tich theo phuong phdp th^
tich dupc trinh hdy d hinh 5. Trong do dpng vat khdng xuong sdng chidm ty le cao nhat (45%), kd den la nganh tdo luc (25%), tao ldng roi Ifich (23%), ddng vat khdng xuong (4%), ddng vat nguyfin smh (3%), mim ba huu co chiem ty le rat nhd (0,2%).
Nhu vay thiic an chidm uu the cua ca ngua xam theo phuong phap nay vdn Id ddng vat khdng xuong sdng, trong khi cdc nganh tdo cung chidm th^ tich ddng kd tiong thanh phan thiic an.
ThAnh phan thiic an Nginh tdo 16nfi roi lech Tio lyc
BOnK vit n^uy^n suih BOnK vit kh6ng xuong sdng BOng vit c6 xinmg sdng Miin b i huu c o
Tong sd m i u phan
lich 40 40 40 40 40 40
M i u b i t gap
sa
luong 12 14 16 28 12 24
Phan lrim(%)
30,0 35.0 40,0 70,0 30,0 60.0 Kdt qua phan tich thdnh phdn thiic an ti-ong hfi thdng tifiu hda cua cd ngua xdm theo phuong phdp tdn so xudt hi^n dupc hinh hay b bang 4. Trong hfi
Wngval
Hinh 5: Phd thiic an cd ngya xdm
N 6 N G N 0 H « | P V A PHAT TRIEN NONG THON - KY 2 - THANG 10/2014
K ^ hpp giua tuong quan cfaieu dai mot va d i i a i Hai tbdn, tan so suat hieii cua tfaiic an tnonghe tfadng tieu hoa va { ^ thuc an theo phmmg [^1^ the licb CO tbe ket Inaa ca ngua xam la Ioai an tap I h i ^ ve dpng
33. fi0nSn con ^ £ & n sinh san 3.3.1. Bsc ^anpbat trien aia tuym saib thw
* Tityea anb ^ccai
+ Giai d o a n t Budng tning giong nhu bai soi chi manh, nho, man tring xam do madi mau dma phat trien.
+ Giai doan IL Buong tning co kich thuoc ldn hon mot it, cb mau hong nhat do co nbieu mach mau va mo lii^ k^hon.
+ Giai doan IIL I b e tich buong tning tang loi, be mat budng tning co mau hdng nhat Mat thuong da phan bifit dupc due caL
+ Giai doan IV: Buong tning cbiem phan lon xoang bung. Cd fb^ nhin ro cac hat tning tron va man vang nhat a bfin trong buong tnmg.
+ Gai doan V: Budng tning dat kidi flnroc lon
n h ^ va a tinh trang sSn sang tfaam gia sioh sSn.
+ Giai doan VL Ftian Idn tning da duoc ph&
moi tmong ngoai, buong tning teo nho laL TodiH>
buong tning m ^ nhao va co mau do bam. Bfin trong budng tnmg cdn lai nhtmg hat tning dr cac gial doan feliac nhan.
* Tuy6i smb ducduc
+ Giai doan I - I t T i ^ o i sinh due dia ca due (tmh sao) chua phat trien. chi la hai spi chl nho di mail bong nhat nSm sat hai b ^ xuong s^ig
+ Giai doan n t Tinh sao co mau hong, co nhi^
mach mau pban bd.
+ Giai doan IV: Tmh sao co mau trang siia, dat kich thuoc ldn nhat va phSn thiiy ro rang.
+ Giai doan V: Hnh sao a trang thai sdn sang tfaam gia sinh san.Tinh tning chiia d ^ trong dng din tinh, toan bo budng tinh c6 mau trang sua
+ Giai doan V t Tmh sao da sinh san xong, b^
mat tinh sao CO mau do hdng, mem nhao.
* Hinb anb chop cat lat budng trung ci ngui xam cat cac giai
W^Ji^...
Hinh 8; Tuy^n sinh due giai in(40X) Hmh 9:Tijy6i sinh due cai giai d o ^ IV (4CB0
92
Hinh 10: Tuy6i sinh due cU giai doan V (4aX)
N O N G N G H l l P V A PHAT THEN N O N G THON - KY 2 - THANG 10/20W
KHOA HOC C O N G NGHi
Hinh 11: Tuydn sinh due due giai doan I (40X)
-i , t
Hinh 12: Tuyen sinh due due giai doan II (40X)
Hinh 13: Tuydn sinh due due giai doan III (4030 3.3.2. Sue sinh sin tuydt ddi vi tuang ddi
Hmh 14: Tuydn suih due due giai do?m IV(4050 Sue sinh sdn tuyet ddi va tuong ddi cua ca ngua xdm duoc trinh bay d bang 5.
Bang 5: Siic sinh san tuyet ddi vd tuong ddi cua cd ngyra xdm STT
1 2 3 4 TB
Khoi luong than
fe)
570 810 580 450 602,50±150,42
Khoi luong bu6ng
trtngfe)
33,2 29,0 29,8 26,2 29,55±2,88
Sire sinh san tuyet doi (tnmg/ca the)
4.604 7.842 3.924 3.747 2.943±3752
Siic sinh san tuong doi (trimg/ g ca cai)
8,1 9,7 6,8 8,3 8±1,2 Bang 5 cho thdy siic sinh san tuyet ddi cua cac
mau ca ngua xdm dao ddng tir 3.747 ddn 7.842 himg/cd tiid. Siic sinh san tuyet ddi cao nhat bat gap d cd tiid cd khdi luong ldn nhat (810 g) vd sue san thap nhdt bdt gap d cd thd cd khdi luong nhd nhat (450 ^ . Siic sinh sdn tuong ddi cua cac mdu ca ngua xdm dao dpng 8,1 - 9,7 tning/g cd cai.
So sdnh siic sinh san cua cd ngua xdm vol mdt sd lodi thudc hp cd chep cho tiiay cd ngua xam la loai cd sue sinh san thap hon so vdi cd me Vinh, me trdng, tidm cd, tidi rohu va ca chep (Le Xuan Nhu va cdng tdc vifin, 1994). Siic smh san phu thudc vdo dieu kifin mdi trudng sdng (nhat la dieu kifin dinh dudng vd didu ki§n nhifit dd), vao tap tinh sinh san cua cd.
Thdng tiiudng nhiing loai cd tning nhd, lugng noan hodn it vd nhiing lodi khdng cd tap tinh bao vfi tning, khdng bao vfi con cd sue sinh san cao. Nhiing loai cd kich tiiude tning ldn va cd tdp tinh bao ve tning va con sfi cd siic sinh san thap (Pham Mmh Thanh va Nguyfin Kidm, 2009).
N 6 N G NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 10/2014 4.KErUJAN
Mdi tuong quan giiia chieu dai va khdi lupng ca ngua xam cua cac mau cd cd chieu dai todn than 16,7-49 cm dugc the hien bdng phuong tiinh: W = 0,01 xL^-^^ vdi R^=9,04.
Ca ngua xam khdng cd da day. Chidu ddi rudt trung binh cua cd ngua xdm dai gap 1,73 lan chidu dai than. Nghien cuu thuc an trong rudt ca cho thay day la loai ca an tap thifin vfi dgng vat.
Ca hai do beo Futton va Clark deu cao nhat vao tiiang 12 (Fulton =2,47 va Clark = 2,35) va ke den la thang 6 (Fulton = 2,19 va Clark = 2.04). Uep theo la thdng 5 vd thap nhat vao tiiang 11 (Fulton = 1,95 va Clarke 1,82).
Sue sinh san cua cd ngua xam thap hon nhi^u so vdi cdc lodi ca cung hg cd chep. Sue sinh sdn tuyfit ddi ndm tiong khoang 3.474-7.842 tning/ca Uid va siic sinh sdn tuong ddi khoang 8,1-9,7 tning/g cd cdi.
93
Till Idu TMM KHAO
1. Baird, I. G., V. hithaphaisy, P. Ksouvannalath, B. Phylavanh and B. Mounsouphom, 1999. The Bshes ol southern Lao. Lao Conmunity Fisheries and Dolphin Protection Project Ministry of Agriculture and Forestry. Lao PDR 161 p.
2. Du an Quan ly nghi ca luu vuc song Me Kong, 2005. Kit qua dieu tia nhanh nghi ca luu vuc sdng Sripdk, Tay Nguyen, Viet Nam. 62 h-ang.
3. FAO, 2014. Fishhase: http://www.flshhase.org/
4. Ingram B., Sungan S., Tmggi D . , Sim S. Y. &
De Silva S. S., (2007. Breeding performance of Malaysian wahseer. Tor tambroides and T.
douronensis broodfish in captivity. Aquaculture Research, 38: 809-818.
5. L6 Xuan Nhu va cong tac vien, 1994. Kf thuat nudi ca nudc ngot So Khoa hoc va C6ng nghe tinh An Giang.
6. Pravdin, 1. F., 1963. Huong ddn nghien cuu ca.
Nha xuat ban Khoa hoc va Ky thu&t Ha Noi. Tai heu tieng Vi6t do Pham Minh Giang dich nam 1973.
7. Pham Minh Thanh va Ngayfa Van Ki&, 2009. Co' s& khoa hoc kf thuat san xuit ci gidng, Nha Xuat han Nong nghiep TP. H6 Chi Mmh.
8. Pham Thanh liftm va Tr4n Dac Dinh, 2001 Phucmg phap nghien ctiu sinb hoc ci Tu sach Dgi hoc CanTho. 81 trang.
9. Pham Phuong Loan, 2006. NghiSn cm dfc diim sinh hoc ca Leo (WaUogo attu) tai An Giang.
Luan van cao hoc. Tnrong Dai hoc Cdn Thff.
10. Nguyta Thi Thu He, 2000. Biiu ti-a ihu M ca sdng sudi TAy Nguyin. Luan an tien si. Dai hgc Qu6cgiaHaN6i.
11. Nguyta Van Hao va Ngo Sy Van, 2001. Ci nuac ngot Viet Nam. Tap L, Hp ca ch4p. Nhi xu4 ban Nong nghigp Ha N6i.
12. Nguyin Van Triiu, Duong Nhut Long va Bui Chau Tnie Dan, 2006. Nghiin cm dac diim sinh hoc ca kit (Kryptopterus bleekeri Gunther, 1864). Tap chi Nghien ciiu Khoa hoc -Trucmg Dai hoc Cdn Tha 2006: 223-234.
SOME BIOLOGICAL CHARACTERISTICS OF Tor tambroides (Bleeker, 1954) IN CENTRAL HIGHLANDS, VIETNAM
Phan Dinh Phuc, Duong Tuan Phuong Siumnary
From November 2013 to August 2014, seventy individuals of Tor tambroidesv/ere collected irom Srepok nver basin in Buon Don district of Dalt Lak province, Cu Jut district of Dak Nong province, and Lam Ha district of Lam Dong provmce, to study some biological characteristics. The results show that most taxonomical indices of this species were similar to those previous decribed by several authors. Specifically, the dorsal fin is 4/9, pectoral fm is 1/15, anal fin is 3/5; lateral scales number fi^om 22 to 24; usually 4+1/2 scales between the lateral line and the dorsal-fln origin, and body length is 5.2 of the head length. Relative length of the gut is 1.73. The study on food and feeding of this species mdicated that this species is oramvorous. The relaUonship between length and weight was W = 0.0157*L^'*' (R^= 0.904). The fat content mdexes of Futton va Clark were highest in November (Fulton's =2.47 and Clark's = 2.35), and lowest in November (Fulton's = 1.95 and Clark's = 1.82). The absolute fecundity of Tbr/^mSro/rfeswas fi-om 3,474 to 7,842 eggs/female, and relaUve fecundity was 8.1-9.7 eggs/g of female.
Key words; Tor tambroides, relative length of the gut, fat content index, relative fecundity, absolute fecundity.
NguM phan hiSn: GS.TS. Mai Dmh Yta Ngay nhan bai: 11/8/2014 Ngay thong qua phan b i t e 12/9/2014 Ngay duySt dang: 19/9/2014
94 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 10/20M