Tgp chi Khoa hoc - Cong nghe Thiiy sdn So 4/2014
THONG BAO KHOA HOC
KHAI THAC HOfP LY NGUON LOI THtfY SAN
THE REASONABLE FISHING ON FISHERY RESOURCES
To Van Phumtg', TrSn Buc Phu\ Phan Trong Huyen^
Ngay nhSn bai 30/5/2014, Ngay phan bi?n thong qua- 17/6/2014; Ngiy duyet dang: 01/12/2014 TOIM T A T
Bai bdo nay dua ra quan diim xdy dung mo hinh nhdm xdc dinh ditac mice do ctrcmg lifc khai thde hap ly (f^gj - Fishing Effort) di dua ra sdn luang hgp ly (MSY - Maximum Sustainable Yield), von la hai trong cdc thdnh to cua khai thde hgp ly ngudn Igi thuy sdn (NLTS) Xdy dung cdc tiiu chi ddm bdo khai thde hgp ly, tap trung a cdc khia canh dm song cong dong ngu ddn ven biin, moi trudng sinh thdi nguon Igi, sdn lugng khai thde hgp ly huong t&i nghi cd bin vUng..
Trinh bdy ede gidi phdp quan lynhdm dat dugc mice hap ly trong sdn luang, cuang luc vd nguon Igi thiiy sdn md thi ^ai dd vd dang nghien cuu ttien khai, dp dung vdo thife lien nghe cd Viit Nam.
Tie khda: nguon lai thuy sdn. khai thde hgp ly. tieu chi khai thde bap ly A B S T R A C T
This paper gives a perspective to develop models to determine the level of reasonable fishing on resource m terms of _/^jj. - Fishing Effort, MSY - Maximum Sustainable Yield, and resources. Besides, a reasonable fishing norm set are devel- oped focusing on the aspects of coastal fishermen communities, resources ecological environment, reasonable fishing yield towards sustainable fisheries Last, fisheries management solutions are mentioned in order to obtain the reasonable level in yield, fishing effort and fishery resources that have been deployed and applied around the world, the ability to apply to Vietnam's fisheries.
Key words: fishery resources, reasonable fishing, reasonable fishing norm
I. DAT V A N Bt
Khoa hpc nghl cd da du'a ra mot so glal phap, mo hinh nham quan ly t5t hon, hijdng tdi nghl ca du^e phdt triln bin vdng. Trong do, da cd nhilu gidi phap du'ce dua ra nham quan ly, kiem soat eudng lye khai thac. san lirang ddnh bdt trdnh khai thac qua mue v l mat sinh hoc ddn den suy giam nguon lai.
Hay ndi each khac. trong mot nghl ca (dan loai hay da lodi). d l phdt tnin bin vdng thi sinh khdi ngudn Iffi phai a trang thai can bdng. dilu nay co nghTa lirgng thuy sdn ddnh bat ra khoi sinh khdi phai bdng muc tang trirang cua cae loai thuy sdn. Tuy nhien, van de lam sao tinh toan duac mdc do can bdng smh khli nguon lai. eu the han la lam sao xdc dinh mdc 66 san lu^ng bin vdng t l i da (muc hap ly) va mdc do eudng lye tuang dng trong nghl ea de ddnh bat dirac san lu-ang do. Dac biet, xdc dinh dyg'e cac tieu ehi ve
khai thac hap ly NLTS ddng vai tro quan trong trong quan iy hu'dng tdi nghl cd phat triln ben vdng (PTBV) II. edi TU'gNG vA PHU'aNG PHAP NGHIEN cCru 1. Doi tirvng nghien ci>u
Nghien cuu v l mat ly thuylt cac y l u to cua khai thde hap l-} nguIn lal thuy san. tren ca sd da co cdc so Heu thong kd cudng lye va sdn lugng khai thde nghl cd ven bd.
2. Phu'O'ng phap thu thdp thdng tin Thdng tin duac thu thdp tu nhilu ngudn khac nhau (tap trung d ede tap chi ehuyen ngdnh khoa hoc thuy san. sdch, giao trinh, internet, ede ca quan quan ly nha ntfdc ve thuy san .) de tim ra ed sd ly thuyet phii hgp nham xac dinh mdc d6 san lu'ong va cudng lire khai thae hgp ly trong nghe ea
' ThS To Van Phu'ang TriPdng Dai hgc Nha Trang
' TS Tran DLPC Phu: Vien Khoa hpc va Cong nghe khai thac thuy san - Trifc/ng Oai hpc Nha Trang 3 TS Phan Trong Huyen, Trirdng Dai hgc Nha Trang
TRLfdNG OAI HOC NHA TRANG • 59
Tgp chi Khoa hgc - Cong nghe Thuy sdn So 4/2014
Dya trdn nin tdng ly thuylt duac tdng kit, tacgia dua ra bp tidu ehi ddm bdo hogt dOng khai thde hap ly NLTS vCing bien ven bd. dong thdi du-a ra cac giai phdp khai thde hgp 1^ hudng din phdt triln nghl cd ben vung.
3. Phu'ang phap xu> ly thong tin
Cdc nguIn thdng tin ve ly thuylt khai thac hgp ly nguon Igi thuy sdn dugc tong hgp, xd ly mang tinh dp dyng eao vdo thyc tiln nghl ca Vi^t Nam.
Sd dyng phan m i m tin hpc thing ke MS Excel ve md hinh t h i hien mli tuang quan gida cdc thdng so theo thai gian de xac dinh gid tri sdn lugng vd eudng Igc khai thae hgp ly nghl ea ven bd.
ill. K^T QUA NGHIDN CI>U VA T H A O L U A N 1. The nao la khai thac hop ly nguon Iqi thuy san
Quan 1^ nghl ca Id mgt qua trinh phuc tgp ddi hoi sy tich hgp cua cdc y l u to sinh thdi hpc vd ky thuat khai thde nguon Igl. kinh t l xd hoi vd t h i che, tae dpng d i n hdnh vi cua ngu ddn va cdc nhd hogeh djnh ehinh sach (Thao, 2006). Khai thde hgp ly du'gc hieu la ta sd dyng quy mo ngu' eu phu hgp d l khai thde mpt san lugng hodc trpng lu'gng hgp ly md khdng lam anh hudng b i t Igi d i n sy sinh san, sinh trudng vd bo sung trong tyang lai (King. 2003).
Nhu vdy, xdc djnh sdn lu'gng ben vdng tdi da vd cudng luc khai thde du'gc san lu'gng dd Id can thilt, trong do cdc y l u to lien quan nhy: cudng luc khai thac. nguIn Igl thuy sdn. sdn lu'gng khai thde vd moi quan he gli>a chCing c l n dugc quan tam.
2. Mo hinh bieu dien san lirg^ng va cu'dng liPC khai thde hap ly
Trong Unh vyc khai thde thuy sdn. m6 hinh the hidn mli quan he giua sdn lugng vd cudng lye nham myc dieh khai thde hgp ly NLTS dd duac phat trien td edng thde nen tang (1).
Y = q . f . B (1) Trong do: Y la san lugng ddnh bat; q la hd s6 khd ndng ddnh bit; E (f) Id cirdng lye ddnh bat; N la dp phong phii v l nguon lai (thudng Id tru luang nguon Igi B).
D l phdt triln hdm so t h i hien mdi quan hd gida cydng lye vd sdn lugng khai thac hgp ly, md hinh san xuat thdng du dugc dua ra, thu'dng dupe goi Id Md hinh Schaefer (FAO, 2000a ; 2000b). Cdc nha khoa hpc nghl cd tren t h i gidi dp dung phi biln md hinh nay dydi nhieu hinh thde khde nhau, de xac djnh muc dp hgp ly ciJa san lugng va cu'dng lye
khai thde. nhdm t i l n tdi "cdi dich" la khai thde hgp ly NLTS. Diln hinh Id hai md hinh Fox va Schaefer;
cd t h i dua ra cae gid tri tham khdo quan trpng nham su dyng hidu qud t l i da cu-dng lye khai thde iing vdi sdn lugng bin vdng trong thdi gian dai, khi chi sd dyng hai thdng s6 ca bdn vd dan gidn md khong ciin d i n cdc thdng s i v l mgt sinh hpc. sinh khoi vd quan t h i .
2.1. BiSn dOng quin th4 ngudn /pr va ca sa sinh ftpc cua md hinh
Trong mOt tnj" lygng ddn cd khi chu-a khai thac, canh tranh trong lodi cho nguon tdi nguySn, niiu thde an vd khdng gian sing din den can bdng giira nguIn Igi th6m vao td nguon t>6 sung vd sy mIt S\
do ty le chet ty nhien. Nhung khi quy md trd lirgr^
dan cd bj gidm do hogt ddng khai thde. mdc <Sf cgnh tranh nguon tdi nguydn gidm, d i n din lugng ed b l sung vdo nghl cd thydng co xu hudng tang (King, 2003; Thao. 2006),
Theo (Flatten, 2010), try lu'gng dan cd plm thude vao sy phdt trien hay sdc tdi san xuSt sinh hoc cua quIn t h i nguIn lai. Quan t h i nguwi Igi se thay d l l vdi toe d6 khde nhau tuy thu|c vdo trii lugng nguon Igi. eac tham so mdi trydng vd ylu t6 khde nhy: sy bo sung (Recruiment). tang trudng ci the (Growth), ty Ig chet t y nhien (Natural Moriality) vd ty 1§ chet do khai thac (Fishing Mortality), ducre tdm lugc Igi nhu sau :
SI/ thay Si tru' luang = So sung + TSng trtrnng cd thi - Chet do ti/nhl§n - Chet do khai thac
Tuang dng vdi cdng thuc sau:
dP/dt=[R + G ] - M - Y (2) c l n thiet phai quan tam m l i quan he ndy khi n6l den khai thde hgp Ij^ NLTS. bdi le ti> bilu thde (2}, nguon Igi thCiy san dygc khai thac hgp ly neu si/
thay d l l try lugng (dP/dt) d myc edn bang ho|c dyang, hdm y nguon bo sung vd tang trydng cS the lan han phln tu vong do t y nhien va hogt dpng khai thac. hay ndi cdeh khac ty le chit do tu nhi6n vd khai thac se khdng dnh hudng d i n khd ndng tS sdn xuat eua sinh khli trd lugng NLTS. Ddy la y&i t6 quan trgng nhdm dua ra gidi phap quan 1^ hudng den khai thde hgp l^ NLTS.
ChtJ •) ring, cdc nghidn edu ea trdn thyctlvS ly thuylt deu ket lugn rdng sy tdng trydng tu nhlSn cua try lugng ddn ed cd t h i duac bilu diln nhi/
m6 hinh dydng cong tdng trydng dang hinh chuflng nhu' hlnh 1.
60 • TRUONG OAI HOC NHA TRANG
Tgp chi Khoa hoc - Cong nghe Thuy sdn So 4/2014
Kich ihuttcqu^n ddn H u b 1. Bilu difn tang truong q u ^ t h i theo tfairi gian
Nguon: King (2003)
Ting cac y l u t l ldm cdn trd tang trudng vd kieh thieh tang tru'dng la mgt dydng cong tang trydng dgng hlnh chudng vdi mdc tang trudng eao nhat tai mdc tru lugng trung binh (d gii>a). Tang trudng ty nhien Idn nhit d muc d6 X„g,^ trong hinh 1. N l u tdng tripdng t y nhien eua tru lugng bj khai thac. lugng khai thde Idn nhit dgt dugc dng vdi mdc d l trij lugng X^^g,^ dugc gpi la san lugng hgp ly (MSY).
Day Id mdt trong cdc y l u t6 d u thanh va quan trpng nhat de khai thae hgp ly NLTS.
Gid sir mOt vung bien ed sue tai moi trudng Id K va chua cd ca, ta dua vdo ddy mOt lugng ea nhd ban d i u cd khoi lugng sinh hpe Id B. Ddn ca se sinh trudng vd phat triln theo thdi gian vdi toe do Id G = dB/dt, ro rdng luc d i u G se t^ Id thuan vdi B, do dd G = r.B, Tuy nhien. do vung biln chi cd sdc tai mdi tardng Id K. ndn sau mdt thdi gian, tang trudng dat d i n mgt mue ndo dd se tgo ra sy ddng due va toe dp phdt triln (G) v i n tang len nhung vdi mOt ty Ig giam dan. Nhu vdy, tgi bat ky thdi diem ndo, toe dp phdt trien eung ty le thudn vdi kheang khdng gian edn lai cua viing bien (K-B), do do ta ed moi quan
G = -
dB -rB{l-^)
(3) dt ^ K' Trong dd: r la he s i tang trudng ben trong.MSY •
Biomass
Hinh 3. Moi qoan h^ giira s i n \a<fa% khai thac va sinh khoi trir Itrfmg
Ngudn King (2003)
Ihdi gian
Hinh 2. fiirjmg cong logistic (S-shaped) thi hif n gia tdng
$inh khhv t(H gidi han trSn 1^ gid trj K theo thoi gian Ngudn FAO (2000a)
phy thudc vdo ddc tinh sinh hpc v6n cd cua dan cd, B: Sinh khoi dan ea; K: sue tdi mdi trudng
Hai thdnh to quan trpng d l khai thae hgp ly NLTS la san lugng va cudng lye khai thac, cd the dugc tinh toan va xdy dyng Idn td nin tang phuang trinh 3. Ddy Id md hinh the hien biln ddng cua trtr luang dan ed ehua bi khai thac. Khi hogt d6ng khai thde xay ra. dong nghTa vdi viec ta ed mdt "dgi lugng mdt dl" gpi Id Y, ky hidu cho san lugng khai thae ra khdi try lugng dan ca Ty le sdn lugng khai thac bj khau trir va vilt lai bilu thde (3) nhu sau:
^ = r i ; ( i - | - ) - r (4)
v l mdt l;y' thuylt. neu NLTS dugc khai thde hap ly hay mpt nghl cd d trgng thai I n djnh thi san luang khai thae Y se can bang vdi tdng trudng quIn
=#=
dt khai lai nhu' sau:
Y=rB(l-
(5)Dang ehu y, bleu thuc (5) ed dang hinh Parabol vd gid dmh rdng sdn lugng khai thac se dgt cyc dgi khi sinh khoi bang mpt nua mue dp sinh khoi khi ehua khai thde (hinh 3).
MSY
Fishing effort
Hlnh 4. Moi quan h^ gi&a san l i r ^ g va cirjmg l^c khai thde Ngupn- King (2001)
TRLTONG OAI HOC NHA TRANG • 61
Tgp chi Khoa hoc - Cong nghe Thuy sdn So 4/2014
Td phuang trinh 1, ta cd - ^ la sdn lugng ddnh bat tren m|t dan vj eudng lye khai thde, ky hi§u bdng CPUE (catch per unit of effort). Khi dd. PT 1 dygc Viet Igl nhu sau:
/ --q.B <=> B = f _ CPUE
(6)Neu thay t h i vdo bilu thuc 1. 5, 6, se ed: CPUE = CPUE^- f\cPUE^-^'\ vd ddy la phuang trinh dgng dudng thang vdi gid bi dp doe b = -CPUE^. | . , vd gia trj ehdn a = CPUE^.
dd Id dydng thang ed dang:
CPUE = a + b.f (7) Trien khai lal bilu thue (7) theo dan vj eudng lye se cd: Y = a.f + b.f^ (8)
Trong thyc t l , d l tilp cdn md hinh Schaefer phyc vy eho van d l khai thde hgp ly NLTS, chung ta phdl su dyng bp dy ligu dugc thong kd trong chuli thdi gian ddi (nhilu ndm) v l hai gia tii san lugng vd eudng lye khai thde. Td bilu thde 7 vd 8, bang phuang phdp phan tich xd ly so lieu thong kd vd phuang trinh bdc hai. ta cd-
2.2. St/ md r^ng cua mo hinh san Itfong va cuang li/c khai thiic hop I'jf
Mpt s i phien bdn khac d l xac djnh khai thde hgp ly nguon Igi thuy sdn dugc dp dyng trdn t h i gidi. Trong s6 do Id md hinh dugc xdy dyng bdi nhd khoa hoc Fox ndm 1970, sd dyng dudng cong cudng lye khdng doi xung d l thay t h i m l hinh dudng cong parabol doi xung Schaefer. Trong m6 hinh ndy. dudng cong bleu bien mol quan hd
"CPUE gtim khi cu^g It^-c tSng" d l thay t h i eho dudng thing trong md hinh Schaefer. Dudng cong ndy dugc chuyen dll sang dgng dudng thang bing cdeh logarit ty nhidn.
\n(CPUE) = In
7/ ^b.f
(9)Triln khai Igl PT 9. se cd phuang trinh san lugng khdng doi xdng Fox, ey t h i :
Y = f.Qxp[a + b.f] (10)
Khi dd ta ed ede gia tri tham chilu san luang vd cudng lye khai thae hgp 1;^, cy t h i :MSY = (--).exp[a'\]
JMSY 1
Theo t l chdc FAO - so tay hudng d i n tn/t tuyin v l qudn 1^ nghl ed, vl§c lya chpn giua 2 mfl hlnh ndy trd len quan trpng chi khi dgt dygc gid t j tuang d l i Idn. Nd khdng t h i chung minh ring rr^.
trcng hai md hlnh t i t han cdi edn Igi. Cdc nhd quan ly nghl ed ed t h i chpn m|t md hinh md hp eho ring ed t h i hgp iy nhat trong tnj'dng hgp thyc te nghl c5, hay su dyng md hinh khae trong tardng hgp gid trj d<> ligu dgt k i t qud tit. ddng tin cay han (SpaneW Venema. 1998).
2.3. Mdt s6 cong thu-c khiic tim san lupng khai thac hi?ply
Doi vdi nghl cd ma it dugc nghidn cuu, liic dd khing the cd dugc cdc gia tri v l sdn lugng va cudng lye khai thde theo chuli thai gian nhurg Igi cd mgt so gid tii udc lyang v l sinh khli toan phan vd t d vong t y nhidn. Theo FAO (1992), c&ig thuc Gulland udc lugng sdn lugng khai thac hgplj (FAO. 1992), cy t h i :
MSY = 0.5*M*Bv (11) Trong dd: Bv Id smh khli nguyen eua ddn cd; M Id ty Id ti> vong ty nhien
M$t dgng tong quat hda eua cdng thde Gulland dugc d l xuat bdi Cadima eho cdc dan cd bj khai thde nhung so lidu ddnh gid ve chiing d mue dO han ehi vi dy nhu ddn ed da lodi, nhigt ddi (FAO, 1992)
Cdng thuc Cadima dugc md hinh hda dum dang bleu thuc: MSY = 0 . 5 V B (12)
Trong dd : B Id sinh khoi trung binh (hdng nam);
Z la ty Ig ty vong todn phan.
Vi Z = F + M vd Y = F*B (F Id ty Id t u vong do khai thac; Y la san lugng khai thde trong 1 nam nio dd). DP dd. bilu thde (12) ed Uie dugc vilt Igi nhu sau: MSY = 0.5*(Y + M*B) (13)
3. V i n d l sinh thdi nguon Ipi thuy san Hi§n nay. phan Idn cac ngu trudng dang bi khai thae qua mue, kdo theo Id he lyy mdi trudng sinh thai nguon Igi thOy san, ddc bigt la vung bien ven bo bj tdn phd nghiem trpng. Ngu dan sy dyng ngy cy cd hai mdi trudng sinh thai, chat ddy (vi dy: chit nfi, xung dign. ludi kdo kich thudc mdt ludi nhd. kha thac kilu tdn thu - tan digt...) Trong khi cdc hoat dOng khde vung ven bd nhu: nudc vd rdc thdi tii sinh hogt, cac khu cdng nghiep do ra biln; cdc hogt dpng ehgt phd rung nggp man ven bien; cdc hoat dgng phdt tnin ca sd hg ting, hogt ddng du ljch.
tdc ddng rat Idn den vijng biln ven bd.
Nhu vgy, khai thae hgp ly nguIn lgt thCiy san vung bien ven bd, ben cgnh y l u t l eudng lye va san lugng, khdng t h i khdng quan tdm d i n ylu ^ ehinh - dd la nguIn Igi thiJy sdn. Cd nhieu each thi)G giup tdi tgo, bao vd vd phat tnen NLTS vd xdy dyng
62 • TRLTONG DAI HOC NHA TRANG
Tgp chi Khoa hoc - Cong nghi Thuy sdn So 4/2014
rgn nhdn tao duac coi Id md hinh khd thi, von dugcdp dyng nhilu tren the gldi nhung edn mdi doi vdi Viet Nam. Hai ^ nghTa chlnh 36 Id: 1) se gliip ngan cdn cdc loai ngu cy cd tinh huy digt (ngu cy cam) khai thae gan bd ; ii) Id nai tru I n cua cac loai thuy sdn sinh sdng va phdt trien, da dgng sinh hpc dugc cai thign.
Ben canh dd, d l giam dp lye khai thde NLTS vung biln ven bd, can thilt phdi hgn che cudng lye khai thac tai day. M6 chuyen doi nghl nghiep dudng nhy Id gidi phdp bat bupc, hpgc chuyin doi sang phi nghl cd. hoac nghl khai thac khdng dnh hudng tidu eye d i n mdi trydng hg sinh thdi nguon Igi, dae biet, chuyin doi sang nghe khai thae xa bd - nai cd NLTS d l l dao va phong phO. Gd nhu vdy, tinh hgp ly v l v i n d l khai Hide NLTS cd ven va xa bd dugc giai quylt hieu qua. Lue do se giup cho ngu dan cd cupc song tot dep han tir hogt ding "kinh doanh" NLTS 4. S y m v rong van de khai thac hop ly nguon lo'i thuy san
Khai thac hgp 1^ Id v i n d l khoa hgc, xet d gdc dp ky thudt khai thac, da dugc nghien edu va trien khai d nhilu n g h l ea tren the gidi. Khi gia trj san lygng vd cudng lye khai thde hgp ly dugc xdc djnh.
hang loat vdn de lien quan hdu ea phdi ^ kem thi myc tieu khai thac hgp ly NLTS mdi dat dugc thanh cdng. Do vgy. ben cgnh dam bao cac ydu d u ve nguon Igi, sdn lugng, cudng lye khai thde hgp ly d tam "vT md", vdn d l khai thde hgp ly NLTS doi vdi
viing biln ven bd eung ndn dugc hieu vd dam bdo cac ydu c l u (YC) - d t i m "vi md". ey t h i nhu:
YC-1. Hogt dpng khai thde khdng dnh hudng tidu eye d i n mdi trudng sinh thdi viing biln ven bd;
YC-2: Ddm bao dugc quy djnh ve kieh thudc.
thdnh phln cac loai thiiy sdn trong san lugng khai thde;
YC-3: Tdu thuyen va ngy cy khai thde dung nghe hogt dpng theo quy djnh v l phdn vung khai thde;
YC-4: Ndng suit khai Hide (CPUE) I n djnh va phdt trien theo thdi gian,
YC-5: Nhgn ttidc cua cdng ding ngy ddn c l n dugc ndng cao hudng tdi nghe ca ben vung;
YC-6. Ddi sing cua cdng dong ngu ddn ngdy cdng on djnh vd phdt triln;
YC-7: T h i c h i qudn ly dgt dygc dong thugn eao t u eac ben lien quan de khdng edn xung dgt, cgnh tranh trong khai thde.
Tat cd cdc yeu cau b-dn khdng ndm ngodi vide hydng den phdt triln ben vyng nghe ca, tdc la sy phdt trien nham thda man ede nhu eau hien tgi eua con ngudi nhung khdng ton hai tdi sy thda man eac nhu cau eiia t h i hd tucmg lai (Wikipedla, 2014).
Dong thdi cdc tieu chi tren deu ndm trong ede he thing gidi phdp ngan cdn vd dilu chinh dOng ca kinh te trong KTTS cua ngu dan cpng dong ven bien (FAO, 2008). Duac luge hda qua sa do ting qudt dudi ddy (hinh 7).
I KHAI T H A C HQP L ( NLTS I
1 ~ r ^ 1
StaluqngUnilfaichgplfl I NLTSpMltri^ I I Oltag hic klai U c bpp 1 ^
*, :— j , — T T " —
T
X X
r ^
I
I
T"
X JL
GtU jlai^ ngfti cda d ^ co Hinh 7. Sa do minh boa yen c a u ' 5. Giai phap dp dung khai thac hgp ly
De ngdn chan tinh trang khai thde qud muc vd suy giam nguon Igl, cac bign phap qua ly nghe cd hien da dugc ap dyng d phln Idn cdc viing biln trdn t h i gidi. Hidn nay, hau het eac quy dinh quan ly nghe ca deu dudi dgng kilm sodt va mgnh Ignh Cdc quy dinh nay cy t h i hda khdng chi sdn lugng cho phdp danh bat md cdn cd cdeh thue dugc phdp
JL
I GtliphtpdibchMidOngco I a giai p h d p khai t h i c h g p ly NLTS
ddnh bdL Hinh thue thudng thdy eua eac quy i^nh kiem scat vd mdnh Idnh, cy t h i nhu: hgn nggch. gidi han v l kieh cd lodi thuy san. cae han c h i ve cudng lye danh bat hoac mOt so khia cgnh lien quan d i n eudng lye ddnh bdt thye t l . Nhin chung. cae logi hinh hgn che tren dugc xem Id kiem sodt cdc y l u t l d i u vdo hodc dau ra eiia nghl ed (Holland vd cs, 1999 ; Ward vdes, 2004)
TRUONG OAI HOC NHA TRANG • 63
Tgp chi Khoa hoc - Cong nghe Thdy sdn So 4/20n
Bang 1. Phu-o-ng phdp quan ly, gldi phdp ngan can, d i l u chinh dgng co-Cdng cy ngdn c n d$ng ci C6nB cy dl6u chi nfi d$ng c
I Hgn che vdo ngu trudng khai thac;
> Chuang trinh mua Igl tdu;
> Hgn ehi tdu thuyin vd ngy ey;
• Hgn nggch eudng lye ca nhan {han ngach chung);
I Hgn ehi sdn lugng theo tdu khdng ehuyin nhugng;
I Hgn ngach no lyc/san lugng cd nhdn (lEQs).
• Hgn nggch chuyin nhuang ed nhdn (ITQs);
• Thul vd phi thud tdi nguyen;
• Quyen khai thde theo nhdm (bao g I m hgn ngach phdt triln c|ng ding (CDQs) vd qudn ly dya vdo c$ng dong khde;
• Quyin sd dyng lanh t h i (TURFs).
IV. K^T LUAN VA Ki^N NGHj
Khai thac hgp ly la hogt dpng khai thac mgt sdn lupng hcdc trpng lugng ngay hdm nay md khdng Idm dnh hudng bat Igl cho tuang lai xet v l khfa canh sinh san, sinh trudng vd bo sung NLTS trong tuang lai.
Cd mdt s6 md hinh sdn xult thdng dy tfnh toan khd higu qua de xae djnh sdn lugng vd cudng lye khai thde hgp ly NLTS, chang han: Md hlnh Schaefer, md hinh Fox (la hai md hinh can cd so ligu v l cudng lye vd sdn lugng khai thac theo chuoi thdi gian), trong khi md hinh Gulland, Cadima la hai md hinh quan tdm d i n gia tq sinh khli vd ty Id chit todn phan (do khai thde vd t y nhien).
D l khai thde hgp ly NLTS, hdng loat gidl phdp quan ly edn dugc quan tdm nhung gom lai thdnh hai nhdm he thong gidi phdp (nhdm gidi phdp ngdn cdn dpng ea kmh t l vd nhdm giai phdp dilu chinh dOng ea kinh t l ) .
Bp tieu ehi v l khai thde hgp ly NLTS duac dua ra nhdm hudng tdi nghl cd PTBV. C6 t h i ndi, khdng cd mpt gidi phdp dan Id, dan gidn ndo de gidi quylt cdc van d l t i n tgi trong nghl ed da lodi, da ngu ey nhu d Viet Nam hien nay. Bdi tinh phuc tap eua nd
khiln su dyng tdch bi^t bat ky m$t phuang dn giai quyet nao deu khdng hidu qua trong vide khai thac hgp li- NLTS
Trudc thyc t l nay, phuang dn khd thi duy nhit la phuang dn hgp tdc va tong hgp gom quan ly nguIn Igi, tai tgo vd bdo ve nguon Igi, phdt tn^n sinh k l , kinh t l va cpng dong, vd tdi ca c l u cdc hoat dpng qudn ly - dya tren nhdm gidi phdp dieu bel hogt dgng khai thde hgp ly cua ngy dan. Cy thi, doi vdi nhung tdu thude didn phdi cat giam thi cd the, mpt Id cdi hodn chuyen doi sang nghl khai thdcxa bd ed hidu qud kinh t l cao. hai Id gidi ban ddnh dam lam ran nhan tao, Id nai tni I n va phat trien NLTS, dong thdi gay can trd ngu cy khai ^ d c cd tinh huy didt mdi trudng NLTS ven bd, nhdm thyc hidn muc tidu khai thac hgp 1^.
Vide dilu tilt hogt dpng khai thae cd nghTa la tap trung nhilu han vdo cdc gidi phdp lien quan den con ngudi vd cdng dong. Do dd, ede gldi phdp tilp c^n van de phdi tinh d i n ed trong nganh vd ngodi nganh thuy sdn. Ddi hdi sy hgp tae lien bp ehgt che vd giOa ea quan trung uang va dja phuang d l dam bao h^rp tdc va phoi hgp trong Igp k l hogeh vd thyc hign muc tieu quan 1;^ nghl cd hudng tdi phdt tnin bin vung.
TAI LIEU THAM KHAO ning Vi$l
1 I Dijong Tri Thao | 2006. Kinh te hoc quan ly nghe ca. Tnrdng D?i hpc Nha Trang, TlingAnh
2 FAO, 1992. Inhioduction to h-opical fish stock assessment. Part I- Manual. Rome Italy.
3. FAO, 2000a. Report of the Technical Working Group on the Management of Fishing Capacity. L^ Jolla, Califomia, United;
States, 15-18 April 1998. FAO Fisheries Report, No 586, Rome, Italia.
4 FAO. 2000b. Report of the Technical Consultation on the Measurement of Fishing Capacity, Mexico City, Mexico,1999. FAO Fisheries Report, No. 615 Rome, Italy.
5 FAO, 2008 Fishenes management.3. Managing fishing capacity. FAO Technical Guidelines for Responsible Fisheries. No i SuppL3. Rome, 104p.
6 Holland, Dan, Eyjolfur Gudmundsson, and John Gatrs, 1999. Do fishing vessel buyback programs work: A survey of te evidence? Marine Policy, 23(1), 47-69
7. Michael King, 2003. Fishenes Biology. Assessment and Management Blackwell Publishing.
8. Ola Flaaten. 2010. Fisheries Economics and Management Tromso University. Tromso, Norway.
9. Spaire. P. & S. C. Venema, 1998 - Introduction to tropical fish stock assessment. Part 1. Manual. FAO Fishenes Technicd Paper N" 306.1, Rev. 2. Rome, FAO,
10. Ward. J M , Kirley. J E.. Metzner, R., Pascoe, S,. 2004 Measuring and assessing capacity m fisheries 1 Basic concepts and management options. FAO Fisheries Technical Paper No 433/1. Rome. 2004.40p.
,1. Website http://vi.wikipediaorg/wiki/Ph%C3%Alt_tri%El%BB%83n_b%El%BB%81n_v%El%BB%AFngngay tniyc|p:
25/4/2014.
64 • TRUONG OAI HOC NHA TRANG
