524 Hgi nghi Khoa hgc vd Cdng nghebien todn qudc lan thu V
HIEN TRANG TRLTNG CA - CA CON Of VUNG BIEN VEN B d PHIA TAY VINH BAC BQ
Pham OuocHuy, Do Van Nguyen va Dao Thi Lien Vien Nghien ciiu Hdi sdn - Sd 224 Le Lai - Hai Phdng Email: [email protected], pqhuvfajrimf.org.vn
Tom tdt:
Bdo cdo dua tren cdc sd lieu vd mdu vgt vi trimg cd - cd con (TCCC) thu dugc tgi 25 trgm cd dinh (trong dd cd 01 trcim thu mdu TCCC lien t\tc ngdy dim. 4 gi& thu mdu mdt Idn) & vitng bien ven ba phia Tdy vinh Bdc Bd, bao phii tir if 30 din 2l'^30 vT do Bdc vd 105^45 din 10f45 kinh do Ddng. Dd sdu thu mdu dao ddng tir 4 - 30m. Phuang tiin thu mdu la tdu cd ngir ddn TH9079STS, trong thdng 3, 4 vd 5 nam 2011. Sir dung 2 logi lir&i di thu mdu Id: lu&i keo tdng mat vd tdng thdng dirng. Tdng sd dd thu duac 39.729 trung cd (TC) vd 3.203 cd con (CC). TC thu dirge & tdng mat cao han tdng thang dirng. TC & ddi do sdu < 20m bdt gap nhiiu han & ddi do sdu tir 20-30m vd ngirgc lgi doi vai CC. Mat do phdn bd TCCC giira hai tdng nir&c co sir khdc nhau. Tdng mat thir&n^ xuyen cd mat do cao han tdng thdng dirng. Khu virc tap tning TCCC chit yeu & \'ung biin ven ba vd xung quanh cdc ddo.
STATUS OF FISH EGG AND LARVAE IN INSHORE AREA OF THE BAC BO GULF
Abstract:
This report based on fish egg and larvae data collected from 25 stations (including 01 day - night station with sampling frequency of every 4 hours) in inshore area of the Bac Bo Gulf from 17^30 - 21°30Nand 105^45 - i0f45E, at the depth of 4 to 30m. The survey was executed on board the vessel named TH90798TS of a Jishermen in ThanhHoa province from March to May, 2011.
Fish egg and larvae sample collected by two types of net: surface and vertical nets. Total number of sampled fish egg and larvae were 39.729 and 3.203.
respectively. The quantity offish egg collected in surface is observed larger than the one collected from vertical; and at the depth of less than 20m Is larger than at 20-30m. This is contrary to the observations of larvae. Fish sgg and larvae at two water levels are observed different in density. The density offish egg and larvae was observed most dominant at surface and then vertical level. The density offish egg and larvae coastal, estuary and around of islands was observed higher than that In offshore area.
Tieu ban Sinh hgc vd nguon lgi sinh vgt E
1. MO DAU
Tning cd - cd con (TCCC) Id llnh vyc nghien ciiu khoa hpc co ban va cd vai tro thuc tien rat quan trpng, da dugc cdc nude tren the gidi ddnh gid cao vd dua vdo chuang trinh nghien Cliu thudng nien. 6 Viet Nam hign nay, viec xdy dung cdc djnh hudng bao ve nguon lgi ven bd chu yeu dua vao ngudn sd lieu cii, hogc lay tir cdc De tdi khac nhau. Do dd viec quy hoach, phat trien thuy san ven bd khdng the han che dugc cdc khd khan phdt sinh tir thyc te va mang tinh thuc tien chua cao, chua sdt vdi dieu kien hien tai.
Ciing vdi siic ep cua su gia tang ddn sd vd phdt trien cua kinh te, ngudn lgi hai sdn ven bddang ngay mdt suy gidm, doi hdi phdi cd bien phdp quan ly, khai thdc hgp ly, ben virng.
Viec vang mat hdu nhu hoan todn mpt sd loai ca dac san vdn d vung nude ven bd dang la thuc trang can xem xet va danh gia. Mdt trong nhirng nguyen nhan yeu kem trong qudn ly ntnion lgi nghe cd ven bd la sy thieu thdng tin ve bien trang ngudn lgi, nhdt la cac dii lieu ve bdi de vd miia vy sinh san ciia ngudn gidng. Vi vdy, viec nghien ciiu hien trang, phdn bd va sy bien dpng ciia TCCC d vimg bien ven bd cdn dugc d$t ra, cd y nghia dac biet quan trgng nham gdp phan cho viec quy hoach, dinh hudng, phdt trien nghe cd, phii hgp vdi Igi ich ben viing ciia ngudn lgi day tiem ndng nay. Ben canh dd, thdng qua cac hoat ddng nghien cim ve hien trang va vai trd cua TCCC, nham tang cudng y thiic cua cdng ddng dan cu ven bien trong viec bdo ve ngudn Igi sinh vat d viing bien ven bd.
Tir ngudn sd lieu ciia De tdi ""Ddnh gid hien trgng vd di .xudt cdc bien phdp bdo vi tn'rng cd - cd con vd du triing tdm - tdm con & viing biin ven b& vinh Bdc Bd" cac thdng tin ve thanh phdn lodi. phan bo mat dp ciia TCCC se dugc trinh bdy trong bai nay.
2. TAI LIEU VA PHUONG PHAP NGHIEN ClTU 2.1. Tai li^u nghien ciiu
Tai ligu nghien ciru la ngudn sd lieu ve TCCC, thuc hien trong thang 3, 4 yd 5 nam 2011. Moi chuyin thu 30 mdu tdng mat va 30 mdu tdng thdng dirng, trong tdng so 24 tram thu lien tyc va I tram ngdy - dem (4 gid thu mau 1 Idn) d viing bien ven bd phia Tdy vjnh Bdc Bp.
2.2. Phuang phap nghien ciiu + Thiet ke trgm vi:
Khu vyc khdo sat dugc chia thanh cdc mat cdt song song vdi dirdng vT tuyen, vdi dp sau
<30m. Tuy thudc vao cdc tieu vimg md khoang each giiia hai mat cat dao dgng tir 15 den 20 hai ly vd sd tram vi tren mgt m?t cdt tir 1 den 4 tram. Cdc chuyen khdo sat bao gom 24 tram thu mdu djnh ky theo tram vj da xdc dinh vd 01 tram ngdy dem, sd lugng thu mau lap lgi la nhu nhau (Hinh 1).
+ Phuang phdp thu mdu
- Ludi keo tdng m|t: Mieng ludi hinh chii nhdt, chieu dai I,Om, chieu rpng 0,5m. Dien tich mieng ludi la 0,5m^ Kich thudc mat ludi Id 450|am. Ludi dugc thilt kl theo kilu hinh non
Hgi nghi Khoa hgc vd Cdng nghj bien todn qudc lan thu V
cyt. Chilu ddi tinh tCr mi^ng ludi den dng day Id 2m. Ludi dimg dl thu mau d ting nude tu 0,5-Om. Khi tien hdnh thu mdu, ludi dugc thd cdch man tau Idioang 50m vd cd djnh vdo man tau. Hudng thu mau ngugc vdi hudng sdng, toe dd tdu khoang 2 hdi li/gid. Thdi gian thu mau khodng 5 - 7 phut.
- Ludi keo thang dung: Migng ludi hmh trdn, dudng kinh 0,5m, dign tich mieng ludi 0,2m^. Ludi dugc thiet kg ludi giong nhu ludi keo tdng mat. Khi thu mau, ludi dugc thd xuong theo phuang thang diing,' keo thang d^u len tren mat nude, vdi tdc dp khodng Im/gidy.
Lupng nude qua ludi dugc xdc dinh bdng mdy luu tdc ke (flowmetter) gdn d mieng ludi.
Mdu dugc nia sgch bun ddt, chuydn todn bg mdu vdo Ip nhua cd dung tich 1 lit vd bdo quan trong dung dich formaldehyd 5-7% vd mang vS phdng thi nghi$m phan tich
+ Phuang phdp phdn tich vd xir ly sd lieu - Sur dyng cac md td vd khoa phan loai cua cdc tdc gia: Muneo Okiyama (1988), J. M. Lei vd T. Trunski (1989), Jeffrey M.
Leis va Brooke M. Carson-Ewart (2000), A. M. Shadrin et al (2003)... dk xdc dinh ten ciia TCCC. Nhung ddi tugng chua
phan lo^i dugc, se bdo qudn riSng d^ ti§p tyc xac dinh sau nay.
- Lugng nude qua ludi (V) dugc chuySn doi theo cdng thtrc sau:
V = S * T [(X / T) 0,2324 + 0,0497]
Trong dd: S - dign tichmiSng ludi (m^), T - thdi gian keo ludi (gidy),
X - sd vdng quay hen may do lugng nude qua ludi (flowmeter).
- Mat dp TCCC dugc tinh don vi Id ca thl/100(hn^ nude biin.
- Cdc sd lieu ve thdiih phdn loai, m|t dp dugc xur Iy theo phuong phdp thdng ke m6 td thdng thudng vd phdn mem Maplnfor 6.0.
Hinh 1. Sa do trgm vi nghien ciiru ndm 2011
Tieu ban Sinh hgc vd ngudn l0 sinh vdt Bien
3. KET QUA NGHIEN CUtJ 3.1. Thanh phan loai
Qua 3 chuySn khao sat thu duoc 39.729 TC va 3.203 CC. Budc dju da xac djnh dugc 35 loai thugc 31 hg, chi6m 36,03% t6ng si TC va 99,97% t6ng sd CC. Trong do, thang 3 (thu dugc 1.206 TC va 611 CC) bat gap 21 hg va 16 loai, chiSm 45,36% TC va 99,84% CC; thang 4 (4.996 TC va 104 CC) bit gap 15 hg va 9 loai, chiSm 47,72% TC va 100% CC; va cao nhdt vao thang 5 dat 26 hg va 23 loai, chiem 33,80% TC va 100 % CC (33.527 TC va 2.488CC).
So sanh s6 lugng mlu thu dupe ciia 2 loai luai thi luoi tjng mjt co s6 lugng TC cao han nhieu so vol luoi thang dung, nhung thanh phan Ipai khSng cp su sai khac nhieu. Trong thang 3 bit gap nhiSu nhdt la TC hg ca Trich - Clupeidae (chiim 23,13%); nhung sang thang 4 ti le TC hg ca Trich (chiem 16,15%) bit gjp thap hon sp voi TC hp ca Trong'- Engraulidae (dat 23,78%); va sang thang 5, so lugng TC hg ca Trich chiim 21,66% cao han han hg ca Trong, chiem 2,64%. Ben canh do da xudt hien mgt s6 d6i tugng khac co ti le dang kS nhu hp ca D6i - Mugilidae (5,74%), hg ca Bon luai - Cynoglossidae (2,48%), hg ca Moi - Synodontidae (0,98%), hg ca Ban vi - Bothidae (0,25%)... vai so lugng TC gap nhieu lan thang 3 va thang 4.
So sanh theo dai do sau (<20m va tu 20-30m), s6 lugng CC khong co sir chenh kech nhieu, nhung thanh phdn loai thi co su sai khac. CC chii^iu tap tnmg d dai dp sau tir 20 din 30m, chiem 61,41% tong so CC. Xet chung ca 3 chuyen khao sat, dat ti le % cua CC cap nhdt la hp ca Trich (28,47%), sau dp la hp ca Dan lia - Callipnymidae (16,42%), hg ca Bpng tring - Gpbiidae (15,55%), hg ca Trong (6,03%)... Niu xet rieng timg thang thi hg ca Dan lia chiim uu thi hon han (>50%) cr cac thang 3 va 4, nhung sang thang 5 hg ca Trich lai chiim uu the (chiem 36,41%), hg ca Trong chiem 7,56% va hg ca Dan lia chi chiim khoang 1%.
3.2. FhSn b6 mat dp
Xu the phan bo cua TCCC, chii yeu tap tnmg d viing gan bd, noi cd cac cua song do ra va xung quanh cac dap d vung bien ven bd phia Tay vinh Bac Bp. Nhin chimg, mat dg TCCC trung binh tang len theo thdi gian thu mau [Bdng !).
Bdng i. Mat do TCCC trung binh (iSD) a viing bien ven b&phia Tdy vfnh Bdc BQ Thoi gian
thu may Thang 3 ThanK 4 Thang 5 Trunu binh
Luo'i thang dung Trijng ca
47,58±88,30 53S,75±771,62 1.760,56±3.067,39
790,76±1.947,28
Ca con 40,02±36,3S 46,44±55,74 785,23±1.121,26
294,91±728,75
Luoi tSng mat Trung ca 364.54±483,87 1.437,30±1.920,61 11.374,69±17.365,44
4.068,25±11.192,47
Ca con 205,70±S22,43
28,64±50,28 621,05±547,22 301,84±5I1,58 Tir cdc hinh 2, 3 vd 4 cho thdy: Phan bd mat dp TC d tang thdng dtmg thdp nhdt trong thang 3 (<100 tning/lOOOm^), tdng ddn sang thdng 4 va cao nhdt xudt hien vdo thdng 5 (m6t sd tram dat >10.000 tning/lOOOm^). Khu vuc tap trung cd mat dp cao nhat chii ylu d vimg bien ven bd tir Qudng Ninh den Hdi Phdng vd xung quanh qudn ddo Cdt Bd - Long Chau. Xu thi phdn bd TC d tang mat ciing tuong tu tdng thdng diing. Ngoai cdc vimg tap trung tren, glira Hon Me (Thanh Hod) - Hon Mdt (Ngh? An) vd cua song Nhdt Le mat dp TC ciing tuong ddi cao, dat tir 5.000 den 10.000 tning/lOOOm^
1
Hdi nghi Khoa hgc vd Cdng nghj biin todn qudc lan thit V
Hinh 2. Phdn bo mgt do trimg cd tdng thdng dimg (trdi) vd tdng mat (phdi), thdng 3 - 2011
V I E T N A M
ffilAMv
• n u i B * /
IbubHei * j / B
1
HP^/ .
1 ^y"^ sEKi[^>40
'fr^A
H Ll
. . ™ XMi
»
/finA 3. Phdn bd mat do trimg cd tdng thdng dung (trdi) vd tdng mat (phdi), thdng 4 - 2011
Tieu ban Sinh hgc vd ngudn lgi sinh vgt Bien
Hinh 4. Phdn bo mgt dg trung cd tdng thdng dung (trdi) vd tdng mat (phdi), thdng 5 - 2011
Ddi vdi CC: Nhin chung mdt dd CC vao thdng 3 va 4 thdp hon so vdi thdng 5 (cung trong thdi gian nky, nhigt dg trung binh d tdng mat nude bien hong thdng 3 vd 4 thdp hon thdng 5 khodng 5 C). Trong thdng 3 phan bd mat dg chua dugc ro rang, cdn tuong ddi rdi rac khdp vimg nghiM curu. Din thdng 4, da xuat hien mdt sd khu tap trung nhxmg vdi mat dp chua cao, khoang I.OOO - 2.000 cd con/1 OOOm^ nude biin. Sang thdng 5, khu vuc tap tnmg ciia cd con da ro r$t, chu y§u d vung bien ven bd Qudng Ninh - Hdi Phdng, Thanh Hod vd khu vyc qudn ddo Long Chau - Cdt Bd (Hinh 5, 6 vd 7).
Hgi nghi Khoa hgc vd Cdng nghi bien todn qudc Irm^y
V I $ T N A M
8 ffiiFh^
ThiiHM^
-^^'fy
•^o N § . i . i a ^
\
' " ^ ' T
~"^^
Q M , . M ± ^
1 ^ ' .
- ^
RUNG QoS4jii;3»
"Tr^f^T^K-.
t^^iA^^f ^ -
f^"^
(S
• • •
_.
s - ~ B
a ™-«
//in/i 5. Phdn bo mgt do cd con tdng thdng dimg (trdi) vd tdng mat (phdi), thdng 3 ndm 2011
V l j T N A M
9 RiiFUii
T U i n t b .
ItauibBcs 1 J3f
^ s ^ h t - A B V A ^ ^
«^jKgJ
0> ts.'
J --X
o D « g & . ^""•'^^
^-/ *
O ^ L 4 ^ ^
^z^-
y \Hp?aa
•.
/
X. ^ ..w^ifi.^
///nA 6. Phdn bo mat do cd con tdng thdng dimg (trdi) vd tdng mat (phdi). thdng 4 ndm 2011
•Tieu ban Sinh hgc vd ngudn lgi sinh vgt Biin
Hinh 7. Phdn bo mat do cd con tdng thdng dimg (trdi) vd tdng mat (phdi), thdng 5 ndm 2011 So sdnh theo tdng nude thi mat dp CC trung binh d tang thdng diing vd tdng mat chenh Ifch khdng dang ke, dao dgng hi 294 den 301 ca con/ lOOOm^. Khu vyc tap trung cua CC khdng sai khdc nhilu so vdi TC, nhung vdi dien tich phan bd vd m^t dp Idn ban.
Kit qud tren phu hgp vdi nghien ciiu trudc ddy ciia Do Van Nguyen (1977) ve phdn bd mdt dd cua cdc loai hdi sdn d vung biin tir Mdng Cdi den Cira Sdt (Hinh 5); vd Nguyen Thi Thu (1985) da xdc dinh miia vy smh sdn tdp trung cua cdc loai tdm, cd gidng ty nhiSn thu vao ddm nude Ig ven bien phia Bac la tii thdng 4 den thdng 6.
(Ngudn: Dd Vdn Nguyen, 1977}
"—'M
-. ,,.:^p
• " • • - ' \ ^
s ^ l •
Qin •"-*>
i j ^
• • - - ' ' %
'-.- ..^^
.;,..„...X^^^
-iSm>
niD .• ™
• • —
• •
^,;,
Hinh 8. Phdn bd mQt df TCCC cr vimg bien ven ba tir Mong Cdi din Ciia Sot, thdng 5/1976
Hgi nghi Khoa hgc vd Cdng nghe biin todn quoc lan thu V
4. NHAN XET
1. Tdng so da thu dugc 39.729 TC va 3.203 CC. Budc ddu dd xdc dinh dugc 35 loai thugc 31 hp, chiem 36,03% tdng sd TC vd 99,97% tdng so CC.
2. Ludi tdng mat cd sd lugng TC cao hon nhieu so vdi ludi keo thdng diing, nhung thanh phdn lodi khdng cd su sai khdc nhieu.
3. S6 lugng CC theo cdc dai dp sau khdng cd sy chenh lech nhieu, nhung thanh phdn loai thi d ddi dp sdu < 20m phong phii hon ddi dp sdu tir 20 den 30m.
4. Khu vyc xung quanh ddo Cat Ba - Long Chdu (Hdi Phdng), Hdn Me (Thanh Hod) - Hon Mat (Nghe An) vd ciia Nhdt Le (Qudng Binh) khdng nhung phong phii ve thdnh phdn loai md cdn bat gap vdi sd lugng Idn TCCC.
TAI LIEU THAM KHAO
Dd Vdn Nguyen, "Thdnh phdn, mat dg, vd phdn bd tnrng cd - cd con & vitng biin ven ba tir Mdng Cdi - Qudng Ninh t&l Cira Sdt - Hd Tinh trong cdc ndm 1975-1976", Vien Nghien ciiu Hdi Sdn (1977).
Nguyen Thj Thu, 'Ti/i/i hinh tnrng cd - cd bgt & dam nu&c la Hdi Phdng - Qudng Yin ", Phdn Vien Hdi Duong Hpc tai Hdi Phdng (1985).
Leis J M and T Trnski, "The larvae of Indo - Pacific Shorefishes In the New South Wales", University Press, Sydney, 317 pp. (1989).
M Leis and M Carson-Ewart, "The larvae of Indo-Pacific coastal fishes". Fauna Lalesiana Handbook 2, AusU-alian Museum Sydney, pp. 755. (2000).
Muneo Okiyama, "An atlats of the early stage fishes in Japan ", Tokai University Press. (1988).
Shadrin A M and et al. "Atlats of egg and larvae of coastal fishes of southern Vietnam ", Moscow, GEOS (2003).