Tieu ban: TAI NGUYEN SINH VAT BI^N VA N G U O N LQI 253
BIEN DONG THANH PHAN LOAI vA TRLT Lir(;mG TOM, CA, CUA VUNG BAI BOX TAY NGOC HIEN, CA MAU
Ha Phuoc Hiing*, Nguyen Trgng Ho*, Vo Thanh Toan*, Le Thj Ngpc Thanh*, Tran Dac Djnh*, Nguyen Hoang An**
* Khoa Thuy sdn, Dgi hpc Cdn Tha, * * Chi Cue BVNL Thuy Sdn Cd Mau.
L M d D A U
Viing Bai B6i Tiy Nggc Hien, tinh C i Mau (ggi tit la vimg Bai Boi) co difn tich 24.000ha mat nuac, thugc dja phin 5 xa, g6m: Dit Miii, Vien An (huyfn Nggc Hien), Dit Mai (huyfn Nam Cin), Vift Khii, Tan Hung (huyen Cii Nuac). Diy la viing phii sa b6i ling nhanh do ket hgp cic hf th6ng dong chiy bien D6ng, dong chay vinh Thii Lan vai sy dong gop ciia hai song ldn la song Cira Lon v i song Biy Hip tao nen mgt vimg sinh thii die trung, d6c dio cua hf thong hb bien Tiy Nam Bg. Diu nhting nim 1990, vimg Bai Boi nhifu hg din lin chiem, bao vi de nuoi t6m da lim inh huang den m6i truang nuac va tic dgng xau den khu hf sinh thii thiiy sinh vat ciia no, nhung sau do da dugc giii toa fri lai trang thii ty nhien ciia viing. Nhting nim gin diy duai i p lyc din s6 v i ke sinh nhai, nhieu hg din tir cac nai da tim dfn diy de sinh song.
Trong do mgt s6 ho da tan dung ngu6n lgi thiiy sin ty nhien de khai thac ci, t6m, cing lim ting them ip lyc trong vifc bio ve ngu6n lgi thiiy sin tai diy. Vai khu hf sinh thii die trung ciia vimg Bai B6i nhu vay da co nhieu chuong trinh nghien ciru khu hf dgng thyc vat rimg ngap man song quanh viing, nhung rieng vai thuy sinh vat thi chua dugc nghien ciru nhieu, nhit li chua xic djnh diy dii thinh phin cic loii hii sin (torn, ci, cua), miia vu sinh sin v i sinh lugng ciia chung. Muc dich cua nghien ciru niy l i nhim lim ro them va xic djnh lai cic thanh phin loai, miia vu sinh sin va sinh lugng ciia ci, t6m, cua s6ng frong viing v i cung nham de xuit giai phip bio vf hgp ly ngu6n lgi hii sin niy.
n . PHU'ONG PHAP NGHIEN CUU L Dja diem v^ thoi gian nghien cuu
Dja dilm nghien ciru dugc thyc hifn tai khu vyc Bai Boi vai difn tich 24.000ha mat nuac (H.4). Thai gian thyc hifn frr thing 11/2003 din thing 01/2005.
2. NQ! dung va phvong phap nghien ciru - Thdnh phdn lodi cd, torn, cua
Da khio sit qua 12 dgt. M6i dgt co 12 16 (m6i 16 02 ha) dugc chgn ngiu nhien de khio sit.
Tga do, difn tich v i dg sau cic 16 dugc xic dinh boi miy dinh vj (GPS) v i miy do siu do ci. De thu ci, t6m, cua chiing t6i da sir dyng luai Te (rgng 1 Im; cao 1,0 m; mit luai a dyt li 2a = 15mm). Tau dii 12,9m; Rgng 1,7m; mon nuac 0,7m; C6ng suit: 24 CV (H.l).
- Ddnh gid trir lucmg
Trir lugng c i dugc uac lugng theo phuang phip ciia King (1995) theo sin lugng trung binh cua mgt don vj difn tich quet:
254 Tuyen t?p HOi ngtii KHOA HOC T O A N Q U 6 C Vfi SINH HQC B I £ N V A PHAT TRifeN B £ N VCTNG
B = —X —
a v
6 diy: A li difn tich toin viing Bii B6i (A = 24.000ha); a Ii dien tich ciia moi 16 khio sat (a = 2ha); v la hf s6 ci thoit luai hay con ggi la hifu suit dinh bit cua ngu cu. Doi vai luai Te, gii tri v dugc chon li: v = 0,5 (King, 1995); ^ li sin lugng frung binh cua mgt 16 2ha.
Hinh 1. Ban ve khai trien ciia liFai Te
De thu ci s6ng a ting mat, ludi Re (mit luoi a = 30mm vi a = 70mm, vat lifu PA sgi dem) da dugc ip dung. Luoi dugc thi gin tai cic 16 thu miu vi bo tri ngiu nhien theo timg dgt (H.2).
1.5in
Hinh 2. Ban ve khai tri4n cua lifai Re
Tieu ban: TAI NGUYEN SINH VAT BifeN VA N G U 6 N LQI 255
Cic mau ca, tom, cua dugc gitr trong dung djch formaline 4%, dem ve phong thi nghifm Khoa Thuy sin, DHCT, de phin tich.
- Quan hi chiiu ddi vd trpng lirang
M6i quan hf chieu dii v i frgng lugng dugc dinh gii qua phuong trinh hoi qui: ^ "= "^--^
Wlk frgng lugng ciia t6m hoac ci, tinh theo gam; Z, la chieu dii tinh theo cm; a li hing s6 thyc nghiem; b l i tham so tang truong.
- Cdc tham so tdng truang (L-r., K, to)
Cac tham s6 tang truang (L^, K, to) dang duong cong von Bertalanffy (1938) theo chilu dii dac trung ciia m6i loai (Z,,) ung theo timg tu6i c i (/) cung da dugc xic dinh:
L,=L^(\-e-'"-'^')
La:, li chieu dii tifm can cyc dai, tinh theo cm; K li t6c do ting truong (1/nam); /„ li tu6i ly thuyet ma a do chieu dai ciia thuy sinh vat = 0.
Cic gii frj ciia cic tham s6 tang truong nay dugc xic dinh thong qua phin tich tin suit chieu dii v i chuang trinh phin mem miy tinh FMSP (Fisheries Management Science Programme).
- Chi so thuc hiin tdng tnrang <P' (Growth Performance Index)
Chi s6 niy dimg de so sinh sy khic bift ve ting truang gitra cic quan din khi ma cic gii fri Leo vi K tuong quan nghjch vai nhau (Pauly & Munro, 1984):
0'=2logL^-logK
Laa li chilu dii tifm can cyc dai, tinh theo cm; K li t6c dg tang fruong, tinh theo 1/nam.
- [fac lupng long mirc chit Z
T6ng muc chit tuc thai (Z) ciia quin din da dugc tinh toin tiiy theo die diem ciia timg loai ma CO thi tinh theo phuong phip duong cong sin lugng dinh bat dya fren chieu dii LCCC (Length Converted Catch Curve) theo Pauly (1983):
ln[F/dt] = constant - Z.t
F li so ca thi frong m6i lap tuoi; / l i tu6i tuong doi; dl la gii frj thai gian cho timg loai frii qua mgt lorp tuoi nao do.
Ngoii ra, uac luge muc chit Z con dugc tinh theo phuang phap t6ng muc chft trung binh bic thai theo phuang phip Beverton-Holt (1956):
Z^K[(L^-L)/(L-L)]
L la chilu dai friong binh cua ci, bing hoac dii hon I ' . Z ' l i giai ban duai cua khoing chieu dii diu tien ciia c i hoin toin bj dinh bit boi ngu cy.
Tir cac gii tri miic chit a fren, phin frim (%) mirc chft cua quin din dugc tinh theo King (1995):
Mice chit (%) = 100(1 - e^) - S6 lugng v i miia vu xuat hifn torn, c i giong
256 Tuyen tap HOi ngtii KHOA HOC T O A N Q U O C V S SINH HQC B | £ N V A P H A T T R I ^ N B £ N VLfNG
Hinh 3. Lu'O'i tui hinh pheu de thu tdm, Cci gidng
Ba luai tui hinh pheu, tiet difn 1 m" (a = 1mm) dugc diing de thu t6m, c i gi6ng (H.3). Luai thu dugc b6 fri tai truac ngu6n nuac do vio viing Bai B6i, m6i diem thu 3 ngiy lien tiep vio dgt trieu cuong frong thing. M6i dgt thu 15 phiit. lien tiep 4 dgt/gia/diem thu. Mat do v i trir lugng t6m, c i gi6ng dugc tinh tren ca sa lugng nuac di qua mieng luai fren mgt don vi thai gian:
Trie luang giong (theo cd the) = Mat do cd thi/m x The tich nuoc
III. KET QUA VA THAO LUAN
L Bien dong nguon loi torn, ca, cua, muc - Biin dpng ngudn lai tom
Da phit hien 20 loii t6m, thu6c 4 hg (xem phu luc 1). Co 13 loii t6m xuit hifn thuang xuyen (8-12 dgt/ nim) li: The, Sii, Dit, Chi, Bac, Bac nghf, Giang d i . Sat, Giang mit tre, Giang ma, Vic giio, Biu vi tom Tich.
Trir lugng chung cho cic loai t6m uac tinh 125.695kg. Co 8 loai t6m dat trir lugng cao (hem 5.000kg) ii torn Sat ran co trir lugng trung binh cqo nhit li: 32.557kg chiem 25,9%; Ru6c Aki:
15.446kg (12,3%); Vic giio: I4.290kg (11,4%); Bac: 13.438kg (10,7%); Giang di: 12.003kg (9,6%); torn Tich bien: 10.125kg (8,1%); Chi: 7.285kg (5,8%); Bac the: 6.634kg (5,3%).
Uac tinh bien dong trir lugng t6m cic loai dao dgng tir 1.716kg (thing 4) din 95.078kg (thing 10). Trii: lugng t6m trung binh ci nim khoing 24.863kg. Co 2 dgt t6m xuit hifn cao la thing 5 v i thing 10. Vio thing 5 xuit hifn rit nhieu t6m Bac gin nho, ggi la t6m "Cot"; vio thing 10 xuit hifn nhieu t6m Bac co kich ca Ion. Cin phii kiem soit nghiem ngat vifc khai thic ngu6n Igi t6m giong con tir thing 4-6 vi bio vf din t6m b6 me tir thing 9-11.
- Biin dpng nguon lai cua, ghe vd muc
Da thu dugc 6 loai cua-ghe thugc 4 giong ciia 2 hg, gom: Hg Portunidae co 2 giong la:
gi6ng Scylla co 1 loii li S. paramamosain (Cua sen). Giong Portunus co 1 loii li P. pelagicus (Ghe xanh); Giong Charybdis co 3 loii li C. affinis (Ghe di), C. miles (Gh? do), C. bimaculata (Ghe Triim men). Ho Grapsidae chi co 1 giong li Varuna vai 1 loii li V. litlerata (Ghem).
D6i vai Myc, da phit hifn 2 loii muc thugc 2 hg khic nhau li: Hg Sepiidae chi co 1 giong li Sepiella vai 1 loii li S. inermis (Myc nang). Ho Octopodidae chi co 01 giong la Octopus vai 1 loii li O. marginatus (Myc tugc).
Co 3 loai ghe xuat hifn thuong xuyen (8-12 lin/nim) la: Ghe xanh, Ghe d i v i Ghe do. 3 loii khong thudng xuyen li Ghe bimacula, Muc nang v i Myc tugc.
Tilu ban: TAI NGUYEN SINH VAT BifeN VA N G U O N LOI
Uac tinh trir lugng chung cho c i cua, ghe dao dong tir 804kg (thing 11) den 34.530kg (thing 3); trung binh c i nim 8.846kg. Nhin chung, trir lugng trung binh cac loai cua-ghe vi myc trong vTing Bai B6i deu duai 1.000 kg/nam. Nhung rieng ghe d i thi chiem s6 lugng rit cao khoing 6.974kg/nam.
Tru- lugng cua, ghe, myc dat cao nhit vio thing 11 vi thing 3. Cin bao ve cic nguon Igi nay vao thing 10-12 v i thing 2-4 hing nam bai sy xuat hien nhieu c i the chua truoiig thinh, da so dang trong tinh frang li con giong.
- Biin dpng nguon lai cd
Phit hifn dugc 71 loii c i thugc 02 lop, 21 bg, 39 hg, 56 giong (xem Phu luc 1).C6 27 loai xuit hifn thuang xuyen (9-12 dgt/nam) gom: c i Duoi; Com; Lep viy ngyc dii; Ml ga fring; Lat cho; Uc; Chem, San; Lift lon; Dii viy den; Chet; Bong trin; Ho; Luai friu; Doi muc; Doi viy to; Keo; Dua; Kim chim; Phen rau; Niu; Lep vang; Dii chim; Phen ving; Keo do; Chinh; va Due bac. Co 15 loii xuit hifn kh6ng thuong xuyen (5-8 lin/nim) trong vimg li: C i Ngat; Hong;
Noc; Moi ca; Lep huyet; Me gi; Uc thuang; Lift; Nang bac; Noc xanh dom; Due chim; Chai An Do; Du6i difn; Bong xf; v i Dia xanh. Co 29 loai xuit hien khong thuong xuyen (<4 dgt/nam) g6m: Chem; Siru; Thoi loi; Ba thu; Nhim h6; c i Ming; Chinh bac; Ngit cho; c i Dira;
Mu chim niu; Nuc so; ci Noc, ci Khoai; Lich; Chi ving; Hien van; Bong cit; Chim tring;
Mang ech. Vo cho; Sao; Duong; B6ng sop; Bong sao; Keo viy to; vi Luai hiim, ci Lim; Bong lau; D6i viy to; H6ng; va Keo. Dii, qua khio sit cho thiy ca Chem, Thoi loi, B6ng sao, Keo va Doi chi xuit hifn mgt vii lin trong nim, tuy nhien diy li cic loai s6ng thuang xuyen a vimg bai boi nhung do thu miu bing luai Te nen kho bat dugc chiing.
Uac tinh trir lugng cac loai ci dao dgng tir 39.846kg (thing 1) den 717.283kg (thing 5).
Trir lugng trung binh c i nim khoang 212.320kg. Co 9 Ioai ca dat trir lugng cao (tren 5.000kg) la: Lep viy ngyc dai (51.639kg); Lep viy ngyc ngan (5.398kg); Mao ga do (8.070kg); Mao gi fring (9.728kg); Uc fring (35.552kg); Son (28.441kg); Lift soc vang (42.976kg); Dii viy den (6.087kg); Luai triu (8.285kg).
Trtr lugng chung cao fren 400.000kg vao cac thing 5-7 vi thing 11-12. Cac thing con lai trU lugng thip. Tuy nhien dii frir lugng co thap nhung kh6ng the n6i li trir lugng khong ding ke bai do VLing niy chu yeu chi la nai sinh song ciia c i con.
- Quan hi chieu ddi - trpng luang mpt so lodi tom, cd
Moi ouan hf chilu dai - frgng lugng ciia mot so loii torn, ci co gii frj kinh te cao trong viing Bai B6i dugc thi hifn qua phuong trinh hoi qui cho kit qui Bang 1 phin phu luc. Cung qua gii fri b ta thiy da s6 cic loai c i dang trong giai doan con nho. Rieng ca Du co gii tri b>3.
dieu niy cho thiy c i Dii vio diy co thi li de tim nai sinh sin, boi thuang phit hifn buong trirng ciia ci nay dang trong giai doan 4-5.
- Cdc tham so ldng truang cua mot sS qudn dan tom, cd co gid tri kinh te
Tiiy die dilm. ciia loai ma cic tham s6 ting fruong (L,, K, to), lyiirc chet Z; Phin trim (%) mirc chit ciia quan din; v i Chi s6 thyc hifn tang truong 0' ciia mot so loii torn, ci co gii frj kinh te dugc the hifn trong Bing 2 ciia phu luc.
- Biin dpng qudn thi torn giong (lom conj
Xic djnh dugc 9 loii t6m gi6ng vi 01 loii cua giong. LTac lugng tong trii- lugng t6m giong cic loai dat frung binh li 5.966,3 frieu c i thi. Trtr lugng cao nhat la 11.684,4 tneu ci the vao thing 4, thip nhit li 197,1 tneu c i thf vao thing 9. Miia vu xuit hien ciia tirng loai torn hoac cua giong thi khong triing thai gian. Co thi do die tinh xuit hifn ty nhien cua loai. nhung cung con CO thi phu thugc vio thcri dilm, dja dilm thu mau v i phuong phip thu mau. Nhung cin chu \ li bit dau vio diu thing 4 la miia xuit hien ciia torn Bac va mgt so giong torn khic xuit hifn trong viing Bii Boi Tiy Nggc Hiln vai so lugng Ion. do viy cin luu y bio ve nguon lgi nay.
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Ti^u ban: TAI NGUYEN SINH VAT BigN VA N G U 6 N LQI 259^
2. Van de khai thac, bao vf nguon loi thiiy san 6" vung Bai Boi
Bai Boi la viing sinh thii ven bien die trung, doc dio cua vimg bien Nam bg. L i mgt bai uong rit tot cua cic loii t6m, c i con a giai doan hiu iu trung. Nai cung cip cic ngu6n gi6ng ca, torn ty nhien co gii frj kinh te cho cic bai c i ldn frong vimg Nam Bg. Tir die diem ngu6n lgi phong phii va da dang nhu viy, tir liu nong v i ngu din da thiy dugc tiem ning lon vi ca hgi de tin dung khai thic ngu6n lgi thiiy sin tai diy. Cu the li tir nhirng nim diu ciia thip ky 90, nhieu hp din da den diy lin chiem, chit p h i rimg, bao vi mot phin ciia viing Bai B6i de nuoi t6m, giy nen sy tin phi ning ne ngu6n lgi lim, thiiy sin ty nhien tai day. Mat khic, mgt s6 hg din djnh cu liu nim tai diy va mot s6 hg di din ty do cung ra sire, tranh thii khai thic, dinh bit mgt cich rit khong hgp ly ngu6n lgi bang cic phuang tifn co tinh hiiy dift cao nhu luai Te, Re 3 lap, Lu,... Dieu niy da dit ra mgt vin ve ldn v i nan giii doi vai cic cip chinh quyen v i nguai lim cong tic bio vf ngu6n lgi thuy sin li lim sao bio ve co hifu qui ngu6n lgi thiiy, hii sin phong phu vi qui hiem tai diy.
Vai tinh thin trich nhifm, cic ca quan, ban, nginh, doin the v i cic cip chinh quyen da kien quylt va giii toa dugc cic hg dan lin chiem, bao vi nu6i t6m trong viing Bai Boi tri lai nguyen frang v6n co cua no tir nhimg nim 1994. Tir sau 1994, sau khi giii toa Bai Boi thi Sa Thuy sin, Chi cue BVNL Thiiy sin C i Mau da dit ban mot fram kiem ngu tai ip Trai Xeo de quin ly khu vyc niy. K I tilp tir 6/2004 dugc giao ve Dpi Bio vf Khu Bio t6n Bien, Vuon Qu6c gia Mui C i Mau quin ly. Nha co lyc lugng quin ly v i kiem soit tai diy mi viing Bai B6i co the dugc xem nhu vin con l i nai thuan lgi cho cic loii torn, ci con sinh s6ng. C i hai Dgi bio vf (truac vi sau) diu lim khi tot cong tic giim sit ciia minh, c6 gang ngin ngira vi co nhung bifn phip xir phat thich dang doi vai cic hinh thirc vi pham khai thic viing cim.
Tuy nhien dii c6 co ging, c6ng tic niy xem ra vin con gap nhieu kho khan do bai die thii ty nhien ciia viing, tinh khich quan giy ra tir ngu din, nguai dinh bat frgm, va c i tinh chii quan cua nguai lim cong tic bio vf ngu6n lgi thiiy sin. Co the thiy nhu sau:
Do dgc thii tu nhien cua vung:
- Vimg Bai Boi li vimg co film nang thiiy sin cao. Rit thuan lgi cho t6m, c i co gii frj kinh te cao den diy s6ng va sinh sin.
- Li thuy vyc tuang doi rgng, co rimg ngap man bao quanh vi kenh, rach ching chjt.
- Co din cu s6ng sit hai ben ba. Co nhilu hg din djnh cu liu dai, nhung kh6ng it din mai nhap cu gin day, da s6 li nhting nguai ngheo kh6ng co phuang kl sinh nhai nio khic ngoii vifc khai thic thuy, hii sin.
- Li viing nuac ma, thuang xuyen co cic ghe, tau dinh ci v i van tai di qua.
- Li thiiy vyc can nen co thi khai thic thuy sin bing nhieu ngu cu khic nhau.
Do tinh khach quan gdy ra tir nguai vi phgm:
- Do ngheo kho, bin cimg, mgt bg phin cu din xem Bii Boi la nai tim ke sinh nhai, hg bim vio ngu6n lgi thiiy sin v i rimg dl song. C6ng tic xoi doi, giim ngheo, giiip v6n chuyen huong lam in ducmg nhu chua thi giii quylt hit so niy, m i nlu co giai quyft cho dugc mgt so hg thi lai xuit hif n hg ngheo mai tir nai khic tim den diy sinh s6ng.
- Vin con nhieu phuang tifn le ra khong dugc phep boat dgng trong vimg Bai B6i, ching ban luai Te, Lu, luai Keo cua, luai Re 3 lap,... Mat khic cic phuang tifn v i ngu cu niy thuang CO gii thanh re, df mua sam, trang bj.
- Ngu6n lgi ci, t6m phong phii v i doi dao. Do do nguai khai thic nlu \i pham r6i bj phat tien thi lin sau nlu "thoit" dugc thi co the "ga von".
260 Tuyfen lap HQi ngtii KHOA HQC T O A N Q U O C V £ SINH HQC BI^N VA P H A T T R I ^ N B £ N VCfNG
- Mgt s6 ho din diu co nghe nghifp 6n dinh van sim them mgt s6 ngu cu (luai Re, Lu) de franh thii kiem them thu nhap khi miia vu t6m, c i xuit hifn.
- Nhieu phuang tien dinh bit bing luai Te thuong xuyen boat dgng sit Bai B6i nhung mpt khi sin lugng dinh bit kem thi lai len vao Bai B6i de dinh bat trgm hoac d6i khi di ngang viing Bai Boi neu thiy co "ca hpi" thi sin sing thi luai.
Do chu quan tir cong tdc gidm sal vd bdo vi nguon lai thuy sdn:
- Lyc lugng giim sit, bio vf ngu6n lgi thuy sin thi mong, Bai B6i thi rgng, kho kiem soit het, nhit li khu vyc giip viing dugc phep phia ngoii vi lin can ven rirng ngap man.
- Vifc xir phat duang nhu con nhe, phat tien chir kh6ng tjch thu phuang tifn (luai Te).
- Mgt s6 ngu cu nhu Lii, luai Re 3 lap da thu dugc thi lai dugc thanh ly bin lai cho nguai din a khu vyc lin can.
Gidi phdp ndo cho bdo vi nguon lai Bdi Boi
Da CO nhieu qui djnh ve vifc quin ly, xir phat lien quan den khai thic NLTS noi chung va Bai Boi noi rieng dugc i p dung tir cic cip, ban, nginh dja phuong. That sy m i noi cic bifn phip nay phin nao ciing da gop phan ran de nhiing nguai c6 tinh vi pham. Tuy nhien, do d i e thii cua vimg Bai boi nen tinh frang vi pham cung thuong xuyen xiy ra, lim cho cong tic bao vf NLTS a diy lu6n li vin de kho khan, phirc tap. De co the lam t6t c6ng tic bio vf NLTS Bai B6i cin co nhimg giii phip d6ng bg, cin ph6i hgp vai nhieu ca quan, ban, nganh cic cip nham trift tieu dpng ca xem ngu6n lgi thuy sin li ke sinh nhai s6ng con ciia mgt bg phin nong, ngu din trong viing. De trift tieu dgng ca nay de nghj cin thyc hien d6ng bp sau:
- Phoi hgp cic ban, nginh thuong xuyen hgi hgp tuyen truyen, giao due tryc tiep vai nguai din ve y thirc gitr gin vi bio toin nguon lgi thiiy sin.
- Chung qui vifc dinh bit thuy sin viing Bai B6i li bai ngheo kho, bin ciing. Do do c6ng tic xoa doi, giim ngheo, giii quyet c6ng in vifc lim l i viec lim cin thiet v i quan trgng. Cic cap ban, nginh cin h6 trg, giiip v6n, dio tao lai cho n6ng ngu din chuyen nginh nghe khic. Cy the la, ngin hang nen cho vay a dang tin chip de ngu din co v6n, chuyen d6i nginh nghe phii hgp.
Can chii y den cic hg luai Te v i dat Lii. Chinh quyen, ban, nginh, doin the dja phuang cin giai thieu, tiep nhin lao dpng (vi con em ciia s6 niy) co boat dpng dinh bit trong vimg Bai B6i vio lim trong cic ca sa kinh doanh, djch vu khic. Cic lim truang v i Vuon quoc gia Miii C i Mau cin uu tien tiep nhin so lao dpng niy de giao pho cic c6ng vifc phii hgp.
- Kien quyet giio dye, cii tao, fri ve dja phuong cic c i nhan, cic hg tir nai khic den lim in m i CO hinh vi xam pham den ngu6n lgi thiiy sin vimg Bai B6i, xem nguon Igi nay la ke sinh nhai duy nhit ciia hg.
- Cin nghiem cim tuyft d6i luai Te boat dgng trong viing Bai B6i. Co the thiy ring trong khi nghe luai Te da bj cim a tinh Kien Giang thi tai xung quanh viing Bai B6i (Ong Trang, Go Cong) vin con co the boat dpng. Chinh dieu niy da tao dieu kifn cho luai Te dinh bit trii phep trong viing Bai Boi. Kich ca v i phuang tifn ciia luai Te tuong doi nho, lai phii hgp cho ho^t dgng trong viing Bii B6i. Do vay, nf u luai Te vin con co the hoat dgng thi k h i nang vi pham Bai Boi vin con.
- Nghe luai Re 3 lop vi nghe dat Lu se vin con boat dgng trong vimg Bai B6i bai n6ng, ngu dan de dang mua sam khi dieu kifn thuan lgi v i nguai hoat dgng khai thic trii phep kho bj phit hien khi khong co mat tai hifn truang. Do viy nen thuong xuyen thu gom v i fieu buy cic ngu cu nay (chir khong bin lai).
- Cac loai nghe dinh bit khic (luai keo tay, luoi Cua giong, dat Chi,...) cung co inh huong den ngu6n lgi Bai Boi nhirng kho mi cim tuyet doi mpi boat dpng cua no tai viing nay. Do do can thuoiig xuyen kiem tra, giam sit mirc dp khai thic mi co bifn phip hgp ly, cin theo doi
Tieu ban: TAI NGUYEN SINH VAT B | £ N V A N G U 6 N LQI 2 6 1
nhirng hoat dpng ciia cic nghe nay khi thay rang hoat dpng ciia chiing co lien quan va anh huona din nguon lgi torn, ci, cua giong, ching han cic hoat dpng cua luai keo cua, luai keo tom "Cot", luai vot ci Niu.
- Cin b6 sung them 3 fram phu de giam sat vimg Bai Boi: 1 a khu vyc miii Bai Bim, 1 a khu vyc mui Ba Quin, va 1 a Go C6ng. Viec dat them cic tram niy dii se tang them bien chi nhin sy nhung se giiip quan ly them ve bio \ e rimg, co the luin phien nhau kiem tra, giim thai gian di lai, phoi hpp ho frg khi cin thiet.
IV. KET LUAN
Vimg Bai Boi li mpt khu hf sinh thii thiiy sinh vat rit dgc dio vai nguon lgi thuy hai sin doi dao, phong phu, cung la nai xiy ra cic hoat dgng kinh te, khai thic trii phep nguon tii nguyen, giy ra cic vin de phirc tap ve an ninh, xa hpi va bio ve nguon Igi
- Da phit hifn dugc 71 loii c i thugc 56 gi6ng ciia 38 hg va hp phu. Co 20 loai T6m thupc 9 giong ciia 4 hp. Co 6 loii Cua thupc 4 gi6ng ciia 2 hg. Co 2 loii Myc thupc 2 gi6ng ciia 2 hg.
Trir lugng c i bien dpng theo miia, trung binh c i nim khoing 212.320kg. Thip nhit vio thing gieng vi cao nhit vio thing 5.
- Uac tinh bien dgng trii: lugng torn cic loai dao dpng tir 1.716kg (thing 4) den 95.078kg (thing 10). Trtr lugng torn trung binh c i nim khoing 24.863kg.
- L/ac tinh trti: lugng chung cho c i cua. ghe v i myc cic loai dao dgng tir 804 kg (thing 11) den 34.530kg (thing 3). Trti' lugng trung binh ca nim khoing 8.846kg.
- Uac tong trtj- lugng ci gi6ng cic loai trong vimg Bai Boi trung binh li 638,71 tneu c i the.
Cao nhit la 2.996,2 frieu ca the (thing 4), thap nhit la 116,8 trieu ci the (thing 1).
- Uac lupng tong trii' lugng tom, cua gi6ng cic loai xuit hifn trong viing Bai B6i dat trung binh li 5.966,3 tneu ci the. Trtir lugng cao nhat la 11.684,4 trieu c i the (thing 4), thip nhit li
197,1 trifu ci thi (thing 9).
- Da so cic loai torn, ci song trong \iing Bai Boi dang trong giai doan con non, kich ca nho.
Chiing li ngu6n b6 sung cho cic quin dan ci, t6m b6, me sau nay.
- Vimg Bai B6i rit de bj inh huoiig nlu hoat dpng khai thac thiiy sin trii phep con ton tai a diy.
- Tir thing 4-6 la miia vu xuit hifn torn giong; Tir thing 10-12 co xuit hien loai torn c i khic. Tuy nhien, dinh sinh de cho timg loai thi khong trimg thing vai nhau.
- c i n sip xip lai, tao vifc lim khic cho cic hg ngu dan khai thic luai Te.
- Tang cuong giim sit vi dat them mpt so tram kiem soit nho quanh vimg Bai Boi.
V. TAI LIEU THAM KHAO
1. Vuang DT Khang (1963). Ngu Loai, Phin Loai Hpc. NXB Khoa Ky - Vf Sinh. Thugng Hii.
2. Nguyen Khic Huang (1991, 1992, 1993). C i Biln Vift Nam. Nxb Khoa Hgc va Ky Thuat.
3. Nguyen Hiru Phung, Nguyin Nhit Thi, Nguyin Phi Dinh vi Do Thj Nhu Nhung (1997) - Danh myc c i biln Vift Nam. N.xb Khoa Hgc v i Ky Thuat.
4. Nguyen Vin Thuang (1999) - Ngu loai II. Giio trinh giing day, Khoa Nong Nghifp, Truong Dai Hpc Cin Tha .124p.
5. Mai Dinh Yen & ctv (1992). Djnh loai cac loii ca nuac nggt Nam Bp. Nxb Khoa hpc - Ky thuat. 239p.
262 Tuyln t i p HQi nghj KHOA HQC T O A N Q U O C V £ SINH HQC BigN VA P H A T T R I ^ N B £ N VLTNG
6. Fishbase (2004): A global informafion system on fishes. CD ROM, Worfish Center - Philippin Office, Los Banos, Philippines.
7. Holthuis, L. B., 1980. Shrimps and Prawns of the World. FAO Species Catalogue, Vol. 1.
F. A. O., Rome.
8. Rainboth, W. J. (1996). Fishes of the Cambodian Mekong. Published by Food and Agriculture Organization of the United Nations.
9. Somnuk Cahifiam va Mala Suponpan (1992). A Guide to Penaeoid shrimps found in Thai Waters. Aufralian Insfitute of Marine Science, Townsville. Australia. 75pp.
10. Starobogatov, Y. L (1972). Penaeidae (Crustacea decapoda) of Tonkin Gulf. The Fauna of the Tonkin Gulf and condition of Hfe in it Exploitafions of the Fauna of the seas. Acad. Sci.
U. S. S. R. Zoo. Inst.
11. Wen-Young Tseng (1987). Shrimp mariculture. A Practical Manual. NXB ChienCheng.
12. Yu, S. C. (1935). On the Chinese Penaeidaei. Bull. Fan. Memorial frist. Biol. Zool. 6(2).
13. Yu, Hsiang-Ping & Tin-Yam Chan (1986). The Illusfrated Penaeoid of Taiwan. Southem Material Center, Inc.
FISHERY STOCK DYNAMIC AND SPECIES DIVERSITY IN THE BAI BOI- NGOC HIEN WESTERN CONSERVATION AREA IN CAMAU PROVINCE
Ha Phuoc Hung, Nguyen Trong Ho, Vo Thanh Toan et aL
SUMMARY
The Bai Boi-Ngoc Hien Westem Conservation Area in Camau Province is a place for feeding of fishery seeds, and also a spawning ground of fishery species. Under the pressure of people populafion and illegal fishing, this area is being threatened to its ecological sustainability in the future. The purpose of study to identify' of species and to assess their stocks to suggest a solution for using and sustainable management of species in the fiiture. The study identified 71 species of 56 genus of 38 families of fishes; 20 species of 9 genus of 4 families of shrimps; 6 species of 4 genus of 2 families of crabs; and 2 species of 2 genus of 2 families of squids. Stocks offish seeds are changed under seasons, highest (2,996 millions individuals) in April and lowest (117 millions of individuals) in January. For shrimp seeds, highest (11,684 millions individuals) in April and lowest (197 millions individuals) in September. Almost ail fishery species presenfrng in the area are still young they will be a complemented fishery resource to fishery populations living around the area. From Apnl to June is a time for presenting of shrimp seeds in the area therefore it will be wiser if these shnmp seeds are protected effecfively. The Bai Boi area will be devastated seriously if put-net fishing is sfill operated illegally in this area.
Keywords: fish species; fish stock; presenting season.
jj^u ban: TAI NGUYEN SINH VAT BI^N VA N G U O N LQI 26:
PHU LUC
I. Thanh phan loai Tom viing B5i Boi - Tay Ngoc Hien, Ca Mau - Hp Penaeidae co 4 gi6ng:
Gi6ng Penaeus c6 3 loai la: P.lalisulcatus (t6m Nilon), P. monodon (Sii), P. semiculcalus (Rin).
Giong Ferenopenaues co 1 loii l i F. indicus (The).
Gi6ng Metapenaeus c6 4 loii li: M. ensis (Dit); M. affinis (Chi); M. tenuipes (Bac); M.
brevicomis (Bac nghf).
Giong Parapenaeopsis co 5 loai li: P. hardwickii (Giang); P. cultrirostris (Sit ran); P.
tenella (Giang mit fre); P. gracillima (Giang ma); P. hungerfordi (Gay tre).
- Hg Sergestidae co 1 gi6ng la Acetes vulgaris (Ru6c do); A. japonicus (Ru6c Aki).
- Hg Palaemonidae co 3 giong:
Giong Exopalaemon chi co 1 loii l i E. styliferus (Vic giio)
Giong Macrobrachium co 2 loai la M. idae (t6m Biu); M. lanchesteri (Tep bo). Giong Alpheus chi co 1 loii li A. euphrosyne (tom Tich nuac ngpt).
- Hp Squillidae chi co 1 gi6ng v i 1 loii l i Harpiosquilla harpax (t6m Tich bien).
1.
2.
3.
4.
5.
6.
7.
9.
. Th^nh phan loai ca viing Bai Boi - Tay Ngoc Nhdm ho (Heterodontus zebra^
Duoi ngdi (Himantura imabricataj Dudi diin (Narke dipterygia^
Mdng biin fCbanos chanos^
Mdi cd (^Clupanodon thrissaj Lam bung dep (Dussumieria acuta)
Cam thuang (Stolephorus commersonii^
Lep vay nguc ddi f^Sefipinna tatyj Lep den (Setipinna melanochirj 10. Lep vay nguc ngdn (Sedpinna
breviceps^
11. A/ao ga ^o (Coilia macrognathosj 12. Mao gd trdng ("Coilia grayii^
13. Cd Khoai (Harpadon nehereusj 14. Lich (Ophistemon bengalense^
15. Cd Dua (Muraenesox cinereus_) 16. Cd Lgt (Congresox talabon) / 7. Chinh bgc CAriosoma anagoj
18. Chinh rdn (Ophichthus rutidodermaj 19. Cd Ngat (Plotosus canius^
20. Ngat cho (Plotosus lineatusj 21. Bong lau (Pangasius krempfij
Hien, Ca Mau
36.Liit lan (Leiognathus equulus^
37.Liet spc vdng (Leiognathus daura^
38. Cd Hong (Lutjanus erythropterus^
39.Hong vdy ngang (Lutjanus johnii^
40. Ken ndu (Lobotes surinamensis^
41.Sgo chdm (Pomadasys maculatusj 42.Ngng bgc COtolithes ruber) 43. Siru (Parma microdonj
44. Cd Dudng (^Otolithoides biauritus^
45. Dii vdy den (Peimahia pawal;) 46.Dii chdm (Nibea maculata^
47. Chet (Eleutheronema tefradacfylum^
48. Phen rdu (Parupeneus barberinoides^
49. Phen hong (Parupeneus barberinusj 50. Hien vdn (Drepane longimana^
51. Cd Ndu (Scatophagus argusj 52. Bdng Iran (Buds bufisj
53. Bdng spp (Ophiocara porocephalaj 54. Bong xi (Oxyurichthys rmcrolepisj 55.Bong cdi ('Glossogobius giuris^
56. Thoi Ldi (Periophthalmodon schlosserij 57.Bong sao (Boleophthalmus boddarti;
58.Keo vdy nho (Pseudapocryptes elongatus^
264 Tuyen tap HOi ngtij KHOA HQC T O A N Q U O C V ^ SINH HQC BI^N VA PHAT TRifeN B £ N VCfNG
22. Cd Dira (Pangasius polyuranodon^
23. Uc thuang (Arius thalassinus^
24. Uc trdng (^Arius sciurus) 25. Vo chd (Anus sagor^
26. Kim (Hemiramphus far^
27. £)o/wwc (Mugil cephalus^
28. Doi vdy to (Liza macrolepisj 29. Chem (Lates calcarifer^
30. San (Ambassis gymnocephalusj 31. Mu chdm ndu ('Cephalopholis argus^
32. Due chdm ('Sillago maculata^
33. Due bgc (^Sillago sihama) 34. Nuc so (Decapterus maruadsi^
35. Chi vdng (Selaroides leptolepis^
59.Keo vdy to (Parapocryptes serperaster^) 60. Cd Ri cau (Trypauchen vagina^
61.Dia xanh (^Siganus javus^
62.Hd nho (Eupleurogrammus muficusj 63.Ba thii (Hasfrelliger brachysoma^
64. Chim trdng (Pampus argenteus^
65. Chai An Dp (Platycephalus indicus^
66.Luan hiim (Cynoglossus cynoglossus^
67.Ludi trdu fCynoglossus lingua^
68. Noc rang riia (Chelonodon patocaj 69.Noc xanh dom (Tefraodon fluviafrlisj 70. Noc (Tefraodon cutcufia^
71.Hdm ich (Halophryne diemensis/
Bang 1. Quan hf chieu dai - trpng iu>(7ng mot so loai torn, ca trong vung Bai Boi
Loai So mau (n) ~R^
Tom Giang (Parapenaeopsis tiardwickii) Tom Chi (Metapenaeus affinis)
Tom Bac ngh$ (Metapenaeus brevicomis) Tom B9c (Metapenaeus tenuipes) Tom The (Feneropenaeus indicus) Tom Giang mo (Vu nang)(Parapenaeops/s graclflima).
Tom Sit (Parapenaeopsis cultrirostris) Tom Dat (Metapenaeus ensis) ..
Tom Su (Penaeus monodon) Ca MSng (Chanos chanos) Ca Nau (Scatoptiagus argus) Cci Difong (Otolithoides biauritus) Ca Ut (Arius thalassinus)
Ca Keo (Pseudapocryptes elongatus) Ca Chet (Eleutheronema tetradactylum) C i Dii (Pennahia pawak)
Ca Phen (Parupeneus barberinoides) Ca Chem (Lates calcarifer)
1314 512 273 1436 893 336 1648 279 14 34 64 27 35 27 17 34 56 29
0.0117, 0.0083 0.0189 0.0189 0.0073 0.019 0.006 0.0137 0.0879 0.0123 0.0596 0.017 0.0988 0.0145 0.0146 0.0057 0.0133 0.0284
2.7642 2.9384 2.6096 2.6315 2.971 2.5348 3.0561 2.7401 2.1706 2.7639 2.7488 2.6643 2.2193 2.5412 2.8756 3.2104 2.6987 2.7735
0.8719 0.938 0.9006 0.9304 0.8982 0.736 0.9518 0.9002 0.9578 0.9962 0.9266 0.9639 0.9061 0.9438 0.976 0.99 0.9329 0.7738
Tieu ban: TAI NGUYEN SINH VAT BIEN v A NGUPN LQI 265
Bang 2. Cac tham s6 tang tru-o-ng ( L . , K, to), mu'c c h i t Z, he s6 t h y c hien tang tru-crng 0 ' cua mot s6 quan dan torn, ca co gia tri kinh t§ cao viing Bai B6i
Loai
Tom Giang Parapenaeopsis hardwickii
Tom Chi Metapenaeus afTinis Tom Bac nghe Metapenaeus brevicomis
Tom Bac Metapenaeus tenuipes
Tom The Feneropenaeus indicus
Tom Giang m a Parapenaeopsis gracillima
Tom Sat Parapenaeopsis cultrirostris
Tom O i t Metapenaeus ensis Tom Su Penaeusmonodon Ca Nau Scatoptiagus argus Ca Chem Lates calcarifer
L.
(cm) 14 16.2 15 10.3 20 7.06 16.3 16.0 30.0 27.5 168.5
K (1/nam)
0.94 1.0 1.0 0.85 0.99 0.98 0.46 1.0 1.0 0.27 0.12
to
(nam) -0.30 -0.28 -0.93 -0.54 -0.48 -0.05 -0.05 -0.64 -0.86 -0.81 -0.85
Z (1/nam) 2.16 ±0.22
2.22 ±0.26 2.76 ±0.83 0.82 ±0.08 2.35 ±0.25 1.03 ±0.19 0.86 ± 0.02 1.38 ±0.99 0.2 ±0.02 2.50 ± 1.3 0.67 ±0.1
% mCrc chet (1/nam)
85+91 86-92 85+97 52*59 88+92 57+70 57+58 32+91 16+20 70+98 43+54
<t>'
2.32 2.42 2.35 2.10 2.61 1.71 2.76 2.41 2.95 3.45 5.37