Hgi nghi Khoa hgc vd Cdng ngh? biin todn qudc lan thu V
BIEN DONG NGUON LOI QUAN XA CA CAC RAN SAN HO VEN B d VIET NAM
Nguyin Van Quan Vien Tdi nguyen vd Mdi trudng Bien
Email: [email protected]
Tdm tat:
Cdc qudn xd cd sdng trin cdc rgn san hd ven ba Vi^t Nam cd sir da dgng cao ve thdnh phdn gidng lodi vdi 1206 lodi thugc 45Tgidng trong 118 hg dd duac ghi nhdn. Trong so ndy. 779 lodi ducrc xep vdo cdc hg cd san ho dien hinh. Dua vdo gid tri sir dung co thi phdn chia qudn xd cd rgn san hd thdnh hai nhdm: (1) nhdm cd ldm thuc phdm. (2) nhdm cd cd khd nang ldm cd cdnh. Xu the biin dgng vi ngudn lai cua cdc qudn xd cd rgn san ho dug^c thi hiin mdt cdch ro rdng v&i su suy gidm nghiem trgng ve ty 14 nhdm cd trong bgc thang dinh duoTig cda bien: su suy gidm nhanh chdng ve mgt dg ciia nhdm cd dir (cd kich thu&c l&n la ddi tiring ddnh bdt) vd gia tdng nhanh mat do nhdm cd mdi (kich cd ca the nhd. it bi khai thdc). Mgt so de dga den ngudn lgi cd rgn san hd bao gdm cdc nguyen nhdn true tiep (khai thdc huy diet, ddnh cd bdng hda chdt) vd cdcyeu to bdt thuang ciia thoi tiet khdc (ddng td, bdo lU, nhiet do nu&c bien gia tdng. axit hda dgi duong). Su cdn thiit phdi nhanh chdng cd duac cdc cdng cu qudn ly ngudn Igfiphit hgp nhu viec thiet lap vd van hdnh tdt hg thong khu bdo ton biin nhdm bdo v$
cdc rgn san ho ciing v&i ngudn lai sinh vgt bien di kem, thda mdn dugrc cac ddi hdi giira phdt trien vd bdo tdn ngudn tdi nguyen thien nhien biin cua
Viet Nam.
DYNAMICS OF REEF FISHES RESOURCES IN COASTAL CORAL REEFS OF VIETNAM
Abstract:
Coral reef fish commuities distribute in the coastal areas of Vietnam contain high species diversity with 1206 species belonging to 451 genefa and 118 families have been recorded. Among of them 779 species are listed as the typical coral reef fishes. Based on the utilization potentials, the coral reef fish communites can be divided into two main groups: (I) live reef food fish, (2) ornamental fish. The trends of resource dynamic show clearly in fact of fishing down marine food web strategy: rapid reduction in density of the predator fishes (large size body) and increasing of the prey fish (small size body). Several threats cause the depletion offish resources include over fishing practices (destructive fishing, chemical fishing) and other abnormal weather conditions (rainy.
Tieu ban Sinh hgc vd nguon lgi sinh vgt Bien
tropical storm, high sea surface water, ocean acidification). It is enmerging to implement the sufficient management tools such as establishment of the marine protected area network to conserve reef habitats as well as coral dwelling species in long term period.
1. MO DAU
Trong cdc nhdm lodi sinh vdt sdng trong rgn san hd, ca la nhdm ddn ddu trong nhdm dpng vgt cd xuong sdng ve su da dang loai, mac dii su da dgng nay phy thugc nhilu vdo phdn b6 dia ly va cau tnic sinh canh rgn. Cho tdi nay hon 4000 lodi ca RSH da duoc ghi nhdn cd trong 255.300km^ tdng dien tich san hd cdn sdng tren the gidi. CJ Vi?t Nam, cd khai thdc dupe tir cdc RSH ven bd va quanh cdc ddo cd san hd phdn bo khdng chi cimg cdp nguon thyc phdm tai cho cho dia phuong ma cdn phyc vy cho viec xudt khdu cd ran tuoi sdng (ca mii, ca hdng, cd kem) vd nudi ldm cdnh (cd budm, cd thia, cd thdn tien). Mdt sd trnng tam khai thdc cd RSH ciia nude ta tap trung d cdc vimg ran thupc Co To, Cat Ba, Bgch Long Vy, Son Chd (phia bdc) va Nha Trang, Ca Nd, Phii Qudc d phia Nam, gdp phdn ddng ke cho cdng tdc xda ddi gidm ngheo cua cdc dia phuofng cd RSH phat hien.
Tuy vdy, do tinh trgng khai thac thieu qudn ly da kbien cho ngudn lgi cd RSH bi suy giam nhanh chdng d hdu bet cdc rgn. Dieu ndy cd lien quan mdt phdn tdi su thieu cdc thong tin cdn thilt ve hi?n trang va khd nang khai thac ngudn lgi cd ran cua ngudi dan ciing nhu ngudi thuc thi phap ludt (coi ngudn loi hdi sdn la vd tan). Bai bao ndy vdi muc dich ddnh gid lai hien hang ngudn lgi cd rgn san hd vd xu hudng biin dpng theo thdi gian tdi hen CO sd phdn tich nhiing biin dpng hong quin xa ca rgn san hd tai m^t s6 viing ran san ho ven bd Viet Nam.
2. TAI LIEU VA PHU'OfNG PHAP NGHIEN CUtJ
Bh ddnh gia mpt cdch cd h? thdng vl ngudn Igi cd ran san hd, bdo cao nay da sii dyng mpt kh6i lupng Idn tai li^u cd dugc tit cdc dl tdi vd dy dn cd lien quan dugc thyc hi?n bdi Vi?n tdi nguyen vd Mdi trudng Biin tir cdc nam 1990 cho tdi 2010 tai mpt so virng ran san ho trpng diim: Cat Ba, Hg Long, Long Chau, vinh Nha Trang...dugc sii dyn^ dl ddnh gia nhiing thay ddi trong qudn xd cd ran san hd thdng qua chuoi thdi gian quan trdc d cung mdt dja diem khdo sdt.
Cdc phuang phap thu thdp mdu vat vd tu lieu ngoai hien trudng dugc tudn theo cdc phuang phdp nghien ciiu bien hi?n hanh vd cudn s6 tay "Dieu ha* ngudn lgi sinh vdt bien nhi?t ddi" ciia English vd nnk, 1997 [3]. Mdu vat dugc phdn tich tgi phdng tbi nghi8m ciia Vi^n tai nguyen va Mdi trudng Biin. Cdng tdc phan loai (tai hign trudng va phdng thi nghiem) dya theo phuang phdp phdn logi hinb thdi hen cac sdch phdn logi chuyen ngdnh va so sdnh vdi cac ket qud nghien ciiu ciia cac tdc gia trong va ngoai nude [1], [2], [4], [5], [6], [7], [8], [9], [10].
Hgi nghj Khoa hgc vd Cong nghe bien todn qudc lan thu V
3. KET QUA NGHIEN CtTU 3.1. Thanh phan loai
Phan tich vd tdng hgp tit cd cac ket qud dieu tra khao sat vd nghien ciiu da co din nam 2010, da thdng ke dugc thdnh phan loai ca RSH bien Viet Nam cd 1206 loai, thuoc 451 gidng, 118 hg. Cd tbi coi day la danh sach cd RSH biin Viet Nam ddy du nhit tir trudc din nay. Trong tdng s6 1206 lodi dugc phat hi?n, cd 779 loai (Bang 1) thudc cac hg cd san ho tieu bieu.
Bdng I. So lugng lodi trong mdt sd hg cd san hd tieu biiu STT
1 2 3 4 5 6 7 8 9 10
Ten ho HocE HOCE Hoc£
H0C£
HocE Ho ct
Song Son Hdng Mien Sao I Budm Ho cd Thia Hp cd Bang chai
Ho ca Md Hp cd Dudi gai
Ten khoa hpc Serranidae Apogonidae Lutjanidae Caesionidae Haemulidae Chaetodontidae Pomacentridae Labridae Scaridae Acanthuridae
So loai 50 - 52 - 28 - 14 - 16 - 47 - 112 - 94 - 43 - 39 - 3.2. Ddnh gia bien dgng nguon lui ca ran san ho
Khu vuc Cat Bd - Ha Lon^
Tren co sd budc ddu phdn tich su bien ddng ve mat dp trong quan xa ca ran san hd doi vdi mpt sd hp cd dugc lya chgn tgi vimg bien Cat Bd (Bang 2, Hinh 1) hong chudi thdi gian tir 2004 - 2009 cho thdy: ngogi trir hg ca Budm Chaetodonhdae (p>0,05), cdc hg ca kinh te nhu cd Mii Serranidae va hp ca hong Holocentridae va cac hp ca cd kich thudc co the nhd nhu cd thia Pomacenhidae va ca son Apogonidae thi lai cd su khac biet trong khoang thdi gian tir 2004 - 2009 (p < 0,05).
Xu the bien dgng mat dp cd the trong quan xa cd ran san hd khu vyc Cdt Bd - Ha Long theo chieu hudng gidm dan mat dp cd the cdc hp cd cd gia tri thuong phdm cao nhu cd mii, cd hdng, cd son dd vd gia tdng mat dp ca the ciia nhdm cd cd cd kich cd nhd: cd son, ca thia. Hien tugng ndy cd lien quan tdi vi?c khai thdc thieu kiem soat ngudn lgi sinh vdt tren ran san hd ndi chung, ngudn Ipi ca ran san hd ndi rieng d khu vyc nghien ciiu. Rieng hp ca budm Chaetodontidae khdng cd sy biin dpng ve mat dd, dieu ndy cd lien quan tdi kha ndng day la hg cd chua phdi la ddi tugng dugc chii trgng khai thac dS lam cd canh blln d vimg bien Cat Bd, - Ha Long.
Sy suy gidm ve ngudn lgi cdn dugc the hi?n rat rd d vi^c bd sung ngu6n gidng ci con cho cdc quan dan ca bd me. Kit qud quan hac miia mua nam 2010 cho thay khdng c6 sy xuat hien cd gidng thupc loai Epinephelus fasciatus va Cephalopholus boenack d hau
Tieu ban Sinh hgc vd ngudn lgi sinh vgt Biin
het cdc dja diem rgn san hd trong chuyen khdo sdt nay. Trdi lgi, trong cdc chuyin khdo sdt cac ndm 2004 - 2005 thi tan sudt xudt hien ca gidng thupc hg ca song la tuong ddi phd bien hen ran san hd hong khu vyc.
Bdng 2. Biin dgng mgt dg cd the mgt sd hg cd rgn san hd dien hinh trong quan xd cd rgn san hd viing bien Cdt Bd - Hg Long
H9ca Serranidae Apogonidae Pomacentridae Lutjanidae Chaetodontidae
T^c dong Thoi gian (nam): 2004 - 2009
F 4,82
19.70 4,95 1,39
Gi^ tri p 0,03*
0.0001*
0,02*
0,25
* Gid tri chap nhgn P< 0.05
Hinh 1. Xu thi biin dgng mgt do cd thi mgt sd hg cd rgn san hd dien hinh vitng biin Cdt Bd - Hg Long
• Khu vyc vimg bien vinh Nha Trang: cdc nghien cim duoc tien hanh hong cdc ndm tir 2003 d6n 2010 hong phgm vi cua khu bdo tdn bien vinh Nha Trang cho mpt sd nhdn dinh ban ddu nhu sau
- Ddi v&i nhdm cd ldm thirc phdm: Trong so nhdm cd lam thyc pham va la ddi tupng khai thac ciia ngu dan quanh vimg thi hp ca dia Siganidae cd mat dp cao nhat (346 cd the/500m^), diing thii hai Id hg cd md Scaridae vd tiep den la hg ca mii Serranidae, hg cd he Lethrinidae cd mat dp cd the thap nhdt vdi 21 cd the. Xet ve nhdm kich cd thuong pham thi CO tdi tren 70% cdc cd the trong nhdm ndy dugc xep vao nhdm ca cd kich cd nhd (5-10cm), sau dd den nhdm kich cd Idn hon 10-15cm. Rdt it gap nhung ca the cd kich cd Idn hen 30cm, logi trir 5 cd the thupc hp cd mii Serranidae.
- Ddi v&i nhdm cd khd ndng nudi ldm cdnh: ket qua quan trdc giai dogn 2003 - 2010 cho thdy mgt dp nhdm cd cd tiem nang nudi lam cdnh d vimg bien vinh Nha Trang cdn tuang ddi phong phii so vdi cdc vimg biSn d phia Tdy vjnh Bdc Bp ciia Vi?t Nam: hg cd thia dat 917 cd thl/12 diim rgn khdo sdt, hg cd budm 315 cd thi, ca bdnh chai: 362 cd thi.... Tuy nhien kit qua phdn tich ANOVA ve tdc dpng ciia ylu td raiia vu tdi quan xd cd ran san hd
Hgi nghj Khoa hgc vd Cdng nghe bien todn qudc lan thi V
dya vao mat dp cd thi ciia mdt sd bp ca rgn san bd dien hinh thi khong diay cd sy khdc bift vl mat dp cd thi cua hg ca budm Chaetodontidae (p>0,05) (Bdng 3). Mgt trong nhung gia thuyet dugc dat ra la da cd su suy gidm manh ve mat d§ cd the ciia ddn cd bo me bd sung cho qudn dan. Trong nhiing nam 1990 ciia the liy truac, viing bien vinh Nha Trang Id noi cung cdp ngudn ca cdnh nurdc man quan trpng ciia ca nude vd thu gom xuat khau di cac nude. Viec khai thdc bua bai cdc hp cd cd mdu sac d?p va cd gia tii thuong mai cao nhu c4 budm da lam suy giam mat dd cua cdc qudn th6 cd d ddy, ddu tdi suy giam mdt dp ciia nhdm ca trudng tiiamh vd ddi hdi can cd thdi gian ddi hon de phyc hdi.
Bdng 3. Phdn tich phuang sai ANOVA gid tri mgt dg cd the trung binh cda mgt sd hg cd san hd dien hinh liin quan tdi yeu td bien ddi miia v^
Ho ca Serranidae Chaetodontidae Scaridae Acanthuridae Pomacentridae
Gia tri F 4,83
1,39 4,95 7,12 12,6
Chi sop 0,03*
0,25 0,02*
0,009*
0,001*
*Gid tri pphu hop (p< 0,05)
KSt qua nghien ciiu cua Nguyen Van Long va nnk (2009) [6] a khu vuc Nam Trung Bp cho thay xu the chung cua cac quan xa ca ran san ho cr khu vuc la: mat dp tang theo thoi gian, chu yeu nhom ca canh co kich thuoc nho 1 - 10cm va 11 - 20cm. D6i vcfi nhom ca lam thuc pham co kich thuoc > 20 cm nhin chung deu Co xu huong giam ho|ic thay doi khong ro rang do m|t do qua thip (Hinh 2).
800 1
- 200
0
01994-95 0 2002 12003 B2004 12005 12006 12007 D20D8
. F ^
CCi Lao Cham Van Phong NhaTrang Ninh Thuan C^N^
Hinh 2. Bien dong ngudn Iffi cd ran san ho vimg bien Nam Trung BQ (NguySn Van Long, 2009)
Tiiu ban Sinh hgc vd nguon lgi sinh vdt Biin
3.3. Phan tich chuot cac de dga den nguon lgi ca ran san ho
Cd hang logt cdc yeu td de dpa den ngudn Igi cd ran san hd bao gdm cac vdn dl thdi tilt cue doan nhu tdng nhi?tmdt each bat thudng cua nhiet dp nude biin ting mgt (dinh diem d cdc ndm 1997-1998), mua Idn do ddng bao d pham vi cyc bg...gdy chet san hd, lam suy gidm chat lupng noi sinh cu la mgt trong nhirng de dpa din ngudn lgi cd trong khu vuc nghien curu. Ben cgnh dd tdc dpng ciia bi?n tupng khai thdc cd qud muc Id vin dl ddng lo ngai vdi viec phdt trien mgt each d gt ciia nghi lan cd vdi khi do thg lan vo vet tit cd nhiing gi cd the thu lugm dugc md hp bat gap. Nghi nay khdng chi la nhiing de dpa tryc tiep tdi cdc rgn san hd ven bd md cd nhiing rgn san hd xa bd nhu Cdn Ddo, Phii Qudc, Trudng Sa...
Hoat dpng du lich bien dugc khdi xudng trong phgm vi cac khu bdo tdn biin: Nha Trang, Cdn Ddo, Phii Qudc, Cii Lao Cham....dd ddng gdp mdt phdn quan trpng ddi vdi viec tao nguon thu cho cdc boat dpng cua ban qudn ly. Tuy vdy cung cdn chdn chinh lai boat dgng lan ngdm tren ran san hd do hign tugng danh bdt cd trdm bdng each cdu tay, siing bdn cd vdn xdy ra do rat khd kiem soat hdnh vi ciia nhiing ngudi lan dudi nude.
Anh hudng ciia dd thj hda vd cdc boat dpng ven bd: thdng qua viec san lip mat bdng dl xdy dung cac khu vui choi, nghi dudng...ldm tang nhung nguy co gdy due hda Idm chit san hd, suy gidm chat lupng nai sinh cu cua he sinh thdi rgn san hd - mai nha cho cdc lodi sinh vgt bien.
4. KET LU^N VA KHUYEN NGHI
Ket ludn: Quan xd ca ran san hd bien Viet Nam cd tinh da dgng cao ve thanh phan giong loai vdi 1206 lodi, thugc 451 gidng, 118 hp. Trong sd nay cd 779 loai dugc xep vao cac hp cd ran san hd tieu bieu. Ngudn lgi ca ran san hd bien Viet Nam dugc phan chia dua vao nhom gid tn su d\mg: nhom ca ldm thyc phdm vd nhdm cd tiem ndng nudi ldm cdnh vdi xu hudng bien dpng ngudn Igi tuang ddi rd rang: (1) suy gidm manh ve mat do nhdm ca lam thyc pham cd kich thuac Idn vd gid tri kinh te cao, (2) gia tdng ve mat do nhdm ca cd kich thudc nhd (cd tgp) h cd gid tri kinh te. Cac de dga tdi ngudn lgi ca ran san hd bao gdm: (1) nguyen nhdn true tiep: khai thdc qud miic vd danh bat hiiy diet, (2) mat noi sinh cu do cdc hoat dgng tir con ngudi vd cac yeu td ty nhien bdt thudng khdc.
Khuven nghi cho cac nghien ciiu tiep theo: Nen chii trpng nghien ciiu sdu hon ve khia canh nguon lgi do cac nghien cihi trudc day chi mdi de cap tdi cdc nghien ciiu mang tinh chat sa bd ve thanh phdn loai vd cdu tnic khu he cd tai cdc vimg ran san hd trpng diem. Tap trnng nghien ciiu dac diem sinh hpc vd ngudn Ipi cua cdc nhdm ca cd gid tri kinh te, nhdm cd chi thi (cd budm, cd thia, cd mii) phdn bd phd bien trudc day tai viing ran san hd ven bd va nhirng nhdm ca chiem ty trgng Idn ddi vdi cac nghe khai thdc thu cong trong khu vuc nude ven bd. Nghien ciiu ve co cau nganh nghe khai thdc, nudi trdng thiiy san d khu vuc va nhiing ddng gdp ciia nd tdi viec tgo sinh ke, xda ddi gidm ngheo cho cdc cdng ddng dan cii ven bd va mdi lien quan den bien dgng ngudn lgi thuy sdn trong viing nude ven bd.
Hgi nghj Khoa hgc vd Cdng ngh? biin todn qudc lan thu V
TAI LIEU THAM KHAO
1. Allen G.R. (2000), "Marine Fishes of South-East Asia". Western Australian Museum.
2. Bd Thiiy san (1996), Nguon lai cd rgn san hd. Nguon Igri thity sdn Viet Nam, Nxb Ndng nghigp, h. 377-383.
3. English S, Wilkinson C, V Baker (eds) (1997), Survey Manual for Tropica Marine Resources, ASEAN-Australian marine science project, Australian Institute of Marine Science, TownsviUe.
4. Do Vdn Khuong va ctv (2008), Bdo cdo tong hgp ddnh gid ngudn Igri cd rgn san hd a mgt sd vung du kien thiit lap khu bdo ton bien, thupc de tai "Ddnh gid nguon lgi cd rgn san hd a mgt sd viing dt^r kiin thiit lap khu bdo tdn bien vd mgt so lodi hdi sdn cd gid tri kinh ti cao a doc thim luc dia Vi$t Nam. de xudt cdc gidi phdp su diing bin vimg ngudn Igrl", 180 hang. Luu trii tai Vi$n Nghien ciiu Hai sdn.
6. Nguyin Van Long (2009), "Nghien cuu mdi quan he giiia qudn xd cd rgn vdi mdt sd ddc trung vd hi?n trgng rgn san hd d vimg bien ven bd Nam trung Bp", Lugn An Tiin ST Sinh hgc, Vien Hdi duong hpc Nha Trang, 174 hang.
5. Nguyen Hiiu Phyng, Nguyen Vdn Long, Trdn Thj Hdng Hoa (2001), "Ngudn lpi ca ran san hd d vinh Nha Trang" Tgp chi khoa hgc vd cdng nghe biin, 1 (2), tr. 16-26.
6. Nguyen Vdn Qudn (2005) Danh sdch cd khu bdo tdn bien Hdn Mun (kit qud khdo sdt nam 2003-2004), Luu trii tai Vien Tdi nguyen va Mdi trudng bien.
7. Nguyen Van (Juan (2003), Danh sdch cd rgn san qudn ddo Truang Sa (kit qua chuyen khdo sdt cdc ndm 2002-2003), Luu trii tai Vign Tai nguyen vd Mdi trudng biin.
8. Nguyin Van Quan (2004), Danh sdch cd rgn san hd viing biin khu bdo tdn Cd To vd khu bdo tdn bien Cdt Bd (kit ^ud chuyin khdo sdt hai ndm 2003-2004), Luu trii tgi Vien Tdi nguyen vd Mdi trudng bien.
9. Nguyen Van Qudn (2004) "Da dang sinh hgc cd bien ven bd phia bdc Viet Nam" Tuyin tap bdo cdo khoa hgc Hdi thdo Viet Nam - Italia: Bdo ton da dgng sinh hgc ddi ven bd Vi0t Nam, Nha Xb Dai hpc Quoc gia Ha Ngi. tr. 229-235.
10. Nguyin Nhdt Thi va Nguyen Vdn Qudn (2006), Da dgng sinh hgc vd tiim ndng ngudn lgi cd rgn san hd biin Viet Nam. Sdch chuyin khdo, Nxb KH&KT, Hd Ndi.
