Hgi nghi Khoa hgc vd Cdng nghe biin todn qudc ldn thu V
DA DANG SINH HQC VA NGUON LQfl THUY SAN TRONG HE SINH THAI RUTVG NGAP MAN VEN BIEN VIET NAM
Nguyen Quang Hiing, Do Anh Duy Vien Nghien ciiu Hdi san 224 Le Lai - Ngd Quyen - Hdi Phdng
Email: nqhungfgrimf.org.vn
Tom tat:
Trong th&i gian nghiin cuu 03 ndm (2008-2010), di tdi da tiin hdnh 04 dat khdo sdt, nghien ci'ni tgi 04 viing RNM Ddng Rui (Qudng Ninh), Hung Hda (Nghe An), Long San (Bd Ria - VUng Tdu) vd VQG miii Cd Mau. Kit qud nghiin cicu dd xdc dmh duac tdng sd 992 lodi sinh vgt. Trong do, thuc vgt ngdp man bdc cao cd 225 lodi (cdy rirng ngdp man - 221 loai, cd biin - 4 lodi), rong biin (50 lodi), sinh vdt phii du (293 lodi), cd (161 lodi), gidp xdc (112 lodi). dgng vdt thdn mim (146 lodi), da gai (5 loai). Riing TC-CC ddxdc dinh dugc 44 ho vd ATT-TC da xdc dinh duac 17 hg. Tdng trii lugmg tiic thai ngudn lgi thuy sdn u&c tinh tgi 4 vimg RNM (48.284 ha) dgt 36.173 tdn, khd ndng khai thdc bin vitng khodng 18.086 tdn; Tdng trii lugmg tuc thai ngudn lai cdc lodi thuy sdn kinh ti chd yiu u&c u&c dgt 25.039 tdn, chiim khodng 70% tdng tru luang ngudn lgi thuy sdn phdn bd, trong hi sinh thdi RNM.
BIOODIVERSITY AND AQUATIC RESOURCES IN VIETNAM'S COASTAL MANGROVE ECOSYSTEM
In period of 3 years (2008-2010), 4 survey trips were carried out in mangrove ecosystem Dong Rui (Quang Ninh province), Hung Hoa (Nghe An province), Long Son (Ba Ria - Vung Tau province) and cape Ca Mau national Park (Ca Mau province). The research results showed that the total of 992 aquatic species were determined in four surveyed mangrove forests. Among them, there are 221 species'of mangrove trees, 4 species of sea grass, 50 species of sea weed. 293 species of plankton, 161 species of fishes, 112 species of crustacean, 146 species of mollusca. 5 species of echinoderm, 44 familie of fish egg-larva, 17 families of shrimp larva-instar. The total fisheries biomass and Maximum Sustainable Yield (MSY) is estimated 36,173 tons and 18,036 tons respectively in four surveyed mangrove forests (the total of 48,284 hectares). Meanwhile, the total biomass of the economically important species is estimated 25,039 tons occupying 70 percent of the total fisheries biomass in four surveyed mangrove forests.
Tiiu ban Sinh hgc vd nguon lgi sinh vdt Biin
I. M d DAU
Rimg nggp man (RNM) Id net dgc trung cua sinh cdnh cac vung nhipt ddi vd can nhipt ddi. RNM khdng nhiing cung cip cdc Idm sdn co gid tri nhu gd, ciii, thuc phim, thuoc chiia b^nh... ma con Id nai nudi dudng, sinh soi va phat trien nhanh chdng nhilu Ioai thuy hai san c6 gid tri kinh tl nhu tdm, cua, ca, sd, dc... nai kiem an, cu tni, nai lam td, trii ddng cua nhilu Ioai chim nude, chim di cu, trong do cd mdt sd loai dang bi de dpa tuypt chimg.
Tuy nhien, do chua hieu het tac dung to Idn vd nhieu mgt cua hd sinh thai RNM, do nhiing Igi ich kinh tl tmdc mat, nen nhiing hogt dpng khai thdc qua muc va gdy d nhilm nghiem trpng nhu khai thdc ban^ cac Ioai ngu cu cd kich ca mat ludi nhd, danh bdt cd tinh buy dipt, phd rimg nupi tdm d at khdng theo quy hoach, dya dan ra sinh sdng, xay dyng vimg jfinh tl mdi... trong lihung nam gan day da lam thu hep, suy giam dang kl nguon Igi vd da dang sinh hpc trong he sinh thdi RNM.
Xuat phdt tijc thyc te tren, nam 2008-2010 Vien Nghien ciiu Hdi sdn da chu tri thyc hien dl tai: Nghiin dm, ddnh gid ngudn Igri thuy sdn vd da dgng sinh hgc cda mdt so viing rim^
nggp mgn dien hinh di khai thdc hgp ly vdphat trien ben vung. Kdt qua nghien cuu cua de tdi da ddnh gia hidn trang da dang sinh hpc vd ngudn Igi thuy san trong h^ sinh thdi RNM, de xuit cac gidi phap bao tdn va phat trien ben viing da dang sinh hpc va ngudn lgi thuy sdn trong he sinh thdi RNM ven bien Viet Nam.
n. PHU'CfNG P H A P NGHlfeN CtTU n.l. Pham vi nghien cvu
Khu vuc mien Bdc: Vimg RNM xa Bdng Rui, huyen Tien Yen, tinh Qudng Ninh.
Khu vuc mien Trung: Vung RNM xa Hung Hod, thanh phd Vinh, tinh Nghe An.
Khu vuc Ddng Nam Bd: Vung RNM xa Long Son, thanh phd Viing Tau, tinh Bd Ria - Viing Tau.
Khu vvc Tdy Nam Bd: Vudn Qudc gia (VQG) miii Ca Mau thudc dia phdn xd Dat Mui, xa Vien An (huyen Ngpc Hiln) va xa Ddt Mdi (huyen Ndm Can), tinh Ca Mau.
II.2. Thdi gian nghien cihi
Thdi gian nghien cuu trong 03 nam (2008-2010). Trong do tir ndm 2008-2009, d^ tdi dd tiln hdnh 04 dgt khdo sat tai 04 vimg RNM n ^ e n cuu, mdi nam triln khai 02 chuyin dieu tra, khdo sdt, dai dipn cho
miia gid Ddng Bdc vd miia gid fay Nam. ^'"^ ^- ^ ' ^ ^'^"^ ^'^ ^""^ ^ ^ "^'^ *'^"
Viet Nam dugfc dieu tra, nghien cim
Hgi nghj Khoa hgc vd Cdng nghj biin tod» qudc ldn thu V
II.3. Phuong phap nghien cuu
IJ.3.1. Phuang phdp thu m&u vd xu ly mdu
Phuang phdp thu mdu va xii Iy mlu dya theo cac tai lieu cua Uy ban Khoa hgc va Ky thudt Nhd nude (1981), Cue Mdi trudng, Bd Khoa hpc cdng nghe va Mdi tnrdng (1999), WWF (2003), S. Aksomkoae et al. (1987).
11.3.2. Phuoeng phdp phdn logilodi
Phuang phap phdn Ioai lodi dya theo cac tdi lieu cua Pham Hodng Ho (I969,_^ 1991- 1993), Nguyin Htm Dinh vd ddng tdc gia (1993), Nguyen Hoang Tri (1996), Nguyin Vdn Tiln vd ddng tdc gid (2002), Chapman V. J. (1975), Gabriella Bianchi (1984), Tomlison (1986), Myers (I99I), Leis (1991), Kevin Lamprell and Thora Whitehead (1992), Shen et al (1993), Rainboth (1996), Kent E. Carpenter and Volker H. Niem (1998), Takashi Okutani (2000), Nakabo (2002), Jorgen Hylleberg and Richard N. Kilbum (2003), NCBl Taxonomy Browser (2010).
11.3.3. Phttangphdp u&c tinh trii lirgng vd khd ndng khai thdc bin vitng a) Nhom cd, gidp xdc vd dpng vgt thdn mem chan dau
- Tinh trii luong tuc th&i & khu vuc ven rimg (thu bdng luai te):
Ap dung cdng thurc ciia Gulland (1969): B = CPUA * (A/X)
Tinh khdi Iugng mdu tren dan vi dien tich (sinh khdi): CPUA = (XCatch/(t*v*h))/n Trons do: CPUA: la khdi Iugng mau tren 1 don vi dien tich; A: Dien tich vung ven RNM; X: He sd thoat ludi (he sd la 0,5); Catch: san Iugng mau thu dugc ciia me ludi; I:
thdi gian keo ludi; v: van tdc keo ludi, h: dp md cua ludi, n: sd tram thu mau.
- Tinh tra luang tuc th&i mdu & khu vuc trong rimg (thu bang ddng chdn):
Trii Iugng dugc xdc djnh theo_phuang p h ^ cua English & Winkinson (1998) va Michael King (1995): B = (A/a) * (b/v)
Tinh khdi lugng tnmg binh tren mdt dan vi dien tich: b = (2b)/n
Trong dd: A: dien tich vimg trong RNM nghien ciiru; a: dien tich cua mdi tram (d ddng) thu mdu; v: he sd thoat hay hieu sudt ddnh bat cua ngu cu, gid tri v = 0,5; b: sinh khdi mau trung binh ciia cdc tram thu mdu; ^^b: tdng khdi lugng mdu thu dugc tai cdc tram; n. s6 tram thu mdu.
- Tinh khd ndng khai thdc bin vting tdi da (MSY): MSY = 0,5 x B Trong do: B la trii lugng tiic thdi.
b) Nhom dgng vgt than mim chan bung, hai mdnh vo - If&c tinh tru luang tuc th&i:
D I udc tinh trit lugng (W) ciia DVTM d cdc viing bai trilu, su dyng cdng thiic: W = B * S - Khd ndng khai thdc bin vung tdi da (MSY): MSY = W x 0,5
Tiiu ban Sinh hgc vd ngudn lgi sinh vgt Biin
Trone do: B Id khdi Iugng trung binh cua cdc diim thu mdu (g/m^), B ^ (Bi + B2 +....+
Bn)/n, B| la khdi lugng tgi diim thu mdu ngdu nhien thii nhit, B2 Id khdi lugng tgi diim thu mdu ngau nhien thii hai, Bn: Khdi lugng tai diem thu mau ngdu nhien thii n, n la sd ldn thu mdu ngau
mau, S la dien tich thu mau,
III. K £ T QUA NGHIEN CUtJ III.l. Da dang thanh phan loai
Tdng hgp cac kit qud nghien ciru trong 03 nam (2008-2010), dl ldi da xac dinh dugc 992 lodi thudc 07 nhdm Ioai sinh vdt tai 04 vimg RNM ven biin Viet Nam. Kit qud nghien cihi cua dl tdi dugc the hien d Bdng 1.
Bdng 1. Tdng thdnh phdn lodi cdc nhdm lodi thity sdn tgi 4 RNM nghien cuu
TT
I
2 3
4 5
6
7
Nhom loai
Thicc vgt ngap man bgc cao 1. Cay ngap man 2. Co bien Rong bien Sinh vdt phu du 1. Thuc vat phu du 2. Dpng vat phu du Cd
Gidp xdc
1. Tom, torn tit {be bS) 2. Cua, ghe Ddng vat thdn mim I. Dong vat than mem chan dSu 2. Dong vdt than mem chan bung 3. Dong vat than mem hai manh vo Da gai
Tong s6 Ioai
So loai moi viing Dong
Rui 136 133 3 21 156
84 72 75 67 37 30 79 13 36 30 0 534
Himg Hod 143 140 3 14 153
98 55 65 45 28 17 40 8 11 21 0 460
Long Sffn 119 . 118
1 30 174 104 70 72 59 37 22 76 10 29 37 4 534
VQG mm CdMau
121 121 0 27 1S2 101 81 85 66 40 26 94 10 36 48
/
576
T6ng so Ioai xac djnh
225 221 4 50 293 189 104 161 112 60 52 146
17 63 66 5 992 Trong 04 viing rimp ngap m ^ nghien curu, VQG mui Ca Mau co thanh phan loai da dang nhat (576 loai), tiep dSn la RNM Long Son va RNM Ddng Rui (534 loai), Thap nhit la RNM xa Hung Hoa (460 loai).
ni.2. Trung ca - ca con (TC-CC) va au tring torn - tom con (ATT-TC)
Ket qua nghiSn cuu cua dS tai cung da xac dinh dugc 44 hp TC-CC va 17 hp ATT-TC.
Thanh phin loai va mat dp TT-CC, ATT-TC tai cac khu vuc bai b6i, ctra song, ven rung thuong cao hem 6 nhOng khu vuc kenh, lach ttong RNM va gSn khu dan cu. Mat dp bat gSp TC-CC va ATT-TC tai cac khu virc nghien cuu dugc the hien trong Hinh 2.
Hgi nghi Khoa hgc vd Cong ngh^ biin todn guoc^ ic ldn thir V
DAngRui HungHoi Long Son C i M a u
1J2> , e ' " U U ^ «
600 M H *" " ' 213 2« B ^ '
. p i n g ^ j ^ B Bai boi
• Lach v:
Hunfi Ho& Long Son CaMau Dia a
Hinh 2: Phdn bd TC-CC (hinh a) vd ATT-TC (hinh b) theo d&i RNM nghien cim i n . 3 . Udc tinh t r u Iugng va k h a n a n g khai thac ben vihig
III.3.1. Trir lieans vd kha nans khai ihdc neuSn lai cdc nhom lodi thuy sdn
Tdng hop kit qud ddnh aid trii lucme vd khd nana khai thac ngudn loi 03 nhdm loai thiiv sdn chinh duac t h i hiln qua Bdn^ 2. Tdng trii Iugng cdc nhdm loai thiiy san tgi 04 vung rCmg ngdp man udc dgt 36.173 tan va khd nang khai thac ben virng tdi da la 18.087 tan.
Bdng 2. Trie luang vd khd nans khai thdc (tdn) ciia cdc nhom lodi thuy sdn tai 4 vims RNM Nhom loai thuy
san Nhdm Ca Nhdm gidp xdc Nhdm DVTM
Tong cong Dong
Rui 186 562 2.411 3.159
H i m g Hoa
3 8 10 21
L o n g Son
7!
217 1.383 1.672
C a M a u 2.248 6.091 22.984 31.322
T o n g trir lu'Ong 2.507 6.878 26.788 36.173
K h a nang K T / . 2 J J 3.439 13.394 18.087 III.2. Trir Iugng va k h a n a n g khai t h a c nguon Igi t h u y san kinh te chii yeu
Tdng trij luang ngudn lai thiiy sdn kinh t l chu v l u tai 04 vimg RNM udc tinh khodng 25.039 tdn, chiem khoang 70% tdng trir luong ngudn loi thuv san. Khd nang khai thdc bin vOng tdi da ddi vdi nhdm ddi tuang nay la 12.520 tdn (Bans 3).
Bans 3. Trie htons vd khd ndng khai thdc (tdn) ngudn lai thuy sdn kinh ti chii viu & 4 viing RNM
Nhom Ioai thuy san Nhdm Cd Nhdm Gidp xdc Nhom DVTM
Tong cong
Dong Rui 132 398 1.133 1.663
H i m g Hoa
2 6 5 14
Long Son
J i 160 788 1.001
Ca M a u 1.779 4.735.
15.848 22.362
T o n g trir l u p n g 1.966 5.299 17.774 25.039
K h a nang K T 983 2.650 8.887 _ _ i 2 . 5 2 0
niu ban Sinh hfc va ngudn lai sinh vgt Bien
IV.KET LUAN IV.l. Ket luSn
- Kit qua nghien ciju da xac dinh dugc 992 loai thugc 07 nhom loai sinh vat trong he sinh thai RNM ven bien Viet Nam. Trong do, thirc vat ngap man bac cao xac dinh dugc 225 loai (cay rimg ngap man - 221 loai, co bien - 4 loai), rong bijn (50 loai), sinh vat phu du (293 loai), ca (161 loai), giap xac (112 loai), dpng vat thSn mSm (146 loai), da gai (5 loai).
- K6t qua ciing da xac dinh dugc 44 ho TC-CC va 17 hg ATT-TC. Thanh phSn loai va mSt dp TT-CC, ATT-TC tai cac khu vuc bai boi, cira song, ven rimg cao hon o nhirng khu vuc kenh, lach trong RNM va gan khu dan cu.
- T6ng trtt lugng tuc thoi ngu6n lgi thuy san (ca, giap xac va dpng v$t than mSm) tai 4 viing RNM uoc tinh dat 36.173 t ^ , kha nang khai thac ben vimg khoang 18.086 tan.
Trong do, trii lugng tuc thai nguon lgi cac loai thuy san kinh te chu ylu uac tinh dat 25.039 tSn, chiem khoang 70% tong trir Iugng nguon lgi thuy san phan b6 trong he sinh thai RNM.
IV.2. Sl xuat
- Khoanh vimg va bao ve 03 bai giong Ion tai cac vimg RNM D6ng Rui (Quang Ninh), Long Son (Viing Tau) vk RNM VQG mui Ca Mau. Qui dinh cam/han che khai thac thuy san ttong miia sinh san chinh tai cac b§i de, bai giong (khoang thang 3 din thang 5 hang nam).
- Nghi6n ciru xay dung cac giai phap bao ton, sir dung hgp ly nguon lgi cac loai thuy san kinh te, qui hiem. Phat trien m6 hinh quan ly tong hgp tai nguyen dua vao cpng dong.
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