Tgp chi Khoa hoc - Cong ngfie Thuy sdn
THONG BAO KHOA HOC
GIAI PHAP BAG VE NGUON LOI THUY SAN BANG CHA KET HO RAN NHAN TAO TAI HUYEN NUI THANH, TINH QUANG NAM i
APPLYING THE MODEL OF THE FISH AGGREGATION DEVICE (FAD) AND ARTIFICIAL REEFS (AR) TO PROTECT COASTAL FISHERIES RESOURCES - THE CASE OF TAM HAI, NUI THANH, QUANG NAM
Nguyin Trgng Lirong', TrSn Birc Phii', Nguyen Quoc Kh&nh', To V&n Phi Ngay nhan bai. 01,'02,'20I5, Ngay phan bicn thong qua: 06/3/2015; Ngay duyel dang- 15/12/2015
TOM T A T t
Mo hlnh chli liet hap ran nhan tgo dtrac xdy dung tgi vimg bien ven ba xd Tam Hdi, huy4n Nui Hiak, linh Qudng Nam vai quy nio bao phu nen day 382.500 m' vd the tich 5.737.500 mK Nghien ciiu da si i^
phtrang phdp ldn khdo sdi nhdm ddnh gid hieu gud cua mo hinh dot vai khd nang tap trung, bdo vg wJpM Irien nguon /pi' ihiiy sdn ven ba. Sau 5 liiang Inen khai mo hinh ket qua dgt dtrac Id so luang lodi, mgt d$phSii ba Idng nhanh vd piiu thuoc vdo th&i gian. khong gian quanh khu chd - rgn: trong khu chd - rgn so Idng iff 45 len 73 lodi (62,2%). mdl do ldng lir 272 ten I 812 cd iheMOOm^ (gdp 6,7 ldn) a mgl cdl ngang 3 800 cd lhe/400m' a mat cdt dimg: -x^ung quanh khu chd - rgn so lirong lodi tang tir 45 len 64. 58, 47 ll mdl dp ciia chung tdng tir 272 len 1.228. 1.065. 896 cd the/400m' a cdc mat cai ngang tuong ung vol khi cdch 50 m. IOO m vd 150 m. Kel qud khdo sdt con cho ihdy san ho mem, rong vd reu bat ddu phdt Iriin cdc rgn nhdn tgo.
Td- khoa: Chd - rgn. mat dp, nguon loi Ihdy sdn ven ha vd sd luang lodi ABSTRACT
Tlie model of the Fish aggregation device (FAD) and artificial reefs (AR) established in the area of Tam Hai commune. Nui Thanh district, Quang Nam province covers wilh Ihe scale of 382.500 m' Oi.
5 737 500 m' The study has used diving sun>ey meihods with scuba equipments to evaluate the effectiveneM the model for concenlraiive ability, protection and development of coastal fisheries resources. After 5 monk Ihe number and species density have rapidly increased. Depending on the time, suiroundmgs or inside the^
and.AR. the number of species Has increa.sedfrom 45 lo 73 species (62.2%), the density has increasedfmnM to I 812 individualsMOOm- (6.7 limes higher) in the transection and reached 3.800 individuals/400m' 0^
veriual plane Ground the F.4D and AR. the number of species has increased from 45 to 64, 58. 47 speciesm their density has increased from 272 lo 1.228. 1.065. 896 individuals /400m' in the transection correspoi to the distance of 50m. 100m and 150m respectively The survey resulls have also showed that safi corals, i and moss start growing on the artificial reefs.
Ke^^vords• FAD and AR. density, coastal fisheries resources and number of species
• M
l ^ S S S S ' X o Nta ^^f "•*"""•" ™" '''"'*" °"" "*"•"''" '^ "<« •• ""» " « '<-l »*• j *>
' ThS To Van Phipang Tn/crng Dgi hgc Nha Trang ' , ^ ^ 4 6 • T R a O N G D A i H O C N H A T R A N G
• ^gP chi Khoa hoc - Cone n^he Thuy son
I. DAT VAN o e
Cha ket \v^ ran nhan tgo la giai phip ky thugt duffc si> dyng nham t i p trung. bao vg, j j j j phat trien ngufin Igi thuy san, hgn che t i u c i
^ thic theo hudng b i n vung. D i n nay. da cd
^ "^'eu quoc gia ung dyng cha - rgn voi quy mo
^ khac nhau va da mang lai lui ich d i n g k§ giup '^ n g h i ca phat trien on djnh.
' U Khai thic thtiy san cua huyen Nui Thanh la mOt trong nht>ng nginh kinh t l manh, gdp phin '"lit quan trong tgo dipn mao mdi cho dja phuong.
Nang ly^ lau ca phat trien mgnh. s i n lupng khai thac tang nhanh ti> 17.000 t i n (2003) d i n
^ ^ 34.750 t i n (2013) [2]. Tuy nhien, da cd bang Hai ^^^^ "^ ^^ S"y g'am cua ngudn Igi thuy s i n ,
^ j ^ i n h huorng khong nhd d i n phat trien kinh te
!k»" ^ ^^' ^ ^ ^ ^ phuwng. Nang suit khai thac -iffiii? ''^" *^^ ^'^"^ ^"* *^°"9 " ^ ' ^ " nam. *<> 0.62 sffiB*^"'^^ *^°°^^ " " " " S cdn 0,34 tIn/CV (2013)
^^^ [2]. Ca chua t r u i n g thanh bj danh bat chilm tJ
^^frdng Id-n trong co d u san tupng, cd 64,2% c i
^ . co^m dinh b i t b i n g n g h i ludi v i y ; 68,2% c i moi va 86.3% tflm he d i n h bat bing nghi ludi keo chua du kfch &iudc cho phep khai thac [3]. Bfln canh do, cd nhilu d l i tupng khai thac hilm g i p trong nhung nam g i n day nhu ca iajJhlng, c i song, ca mu ...; tinh trang vi phgm ji.inquy ^ n h ve kich thud-c m i t ludi dup'c phep su Kffidyng v i p h i n viing khai thic diln ra pho bien.
im Do do, nghien cuu xay dung md hinh cha - yisrgn tgt vCing bien ven bd huyen Nui Thanh cd tj^i nghia thy^ tien cao. l i m ca sd khoa hpc cho
^*/ipc i p dyng g i i i phip ky thugt trong cong tac si'^ao vp. phit triln nguon Ip-i thuy s i n v i giup gflftfii Uiipn sinh k l cho cflng ding ngu dan.
*^""l. VAT UEU VA PHtfONG PHAP NGHIEN ClAJ I.Vgtli^u
Nghten cuu d i s u dyng md hinh c h i - ran i6 c i c dgc diem sau:
- Vgt ligu: Rgn dupc xay dyng bang be
^^png c6t th6p theo tieu chuin wHa m i c M300;
•e c h i dup'c lam t u t h i n tre, tau la dua;
So 4/2015
day c h i va day lien k i t dupc lam tir day Polypropylen v i khda xoay bang Inox.- K i t c i u : Md hinh cha - ran dugc xay dyng tLF 10 be c h i va 120 dun vj rgn nhan tao, bfl tri thanh 10 cym (mfli cym gom 12 don vi ran va 01 be cha). - Khu vyc xay dyng: Khu c h i • ran dugc gioi hgn trong pham vi 108''40'30" - 108<'41'30'' kinh dp Dflng v i 15°31'00"
I S ' ^ r s O ' vT dp Bac thupc khu vyc mui B i n Than (Tam Hai, Nui Thinh).
- Khoang c i c h giua cac cum cha - ran khoang 150 m, dp sau l i p dat ti> 19 - 22 m va be cha dugc bo tri chim each m i t nudc tu 4 - 7 m .
- Dien tich bao phu n i n day: 450 m x 850 m = 382.500 m=.
- T h l tich vung nudc bao phu: 450 m x 850 m x 15 m = 5.737.500 m^.
Hinh 1. H? rh6ng cha - ran nhan tao 2. Phuomg phap nghien cuu 2.1. Khao sat nguon Igi
Nghien cuu da su dung phuong phip khao sat ngufln lm bien nhipt ddi cua English S., C Wilkinson v i V Baker [5]; phuong phap khao sat nguon Igi ven bd cua Dartnall, Alan AJ va Martin MS Jones [4]
TRUONG OAI HOC NHA TRANG • 47
Tgp chi Khoa hoc - Cong nghe Thuy sdn
2.2. Phuvngphap danh gii
Nghien cu'u da su dyng phuong phip lgn d l d i n h g i i hieu q u i cua md hinh cha - rgn.
Cdng t i e dinh g i i dugc thyc hien c i trudc va sau khi trien khai md hinh.
2.2.1 Tnjdc khi xay dyng mfl hinh c h i - rgn - Thdi gian khao sit: Thing 4/2014.
- Thyc hign l i n khao s i t tren 4 mat c i t (MC) ngang theo hudng vudng gdc vdi bd bien, dien tich quan s i t 100m^/MC (5 m x 20 m), thdi gian lgn 40 - 50 phut/MC, khoing each giua cac mat c i t khoang 100 m.
2.2.2. Sau khi x i y dyng cha - ran - Thdi gian khao sit: Tu thing 6 - 10/2014, mdi thing tien hinh khao s i t 01 dgt. C i c dgt khao s i t thyc hien dinh g i i c i trong va xung quanh khu c h i - rgn.
- Mit c i t ngang (song song v i s i t day bien): X i c djnh thinh phin loii, mgt dd sinh vit day trong va xung quanh khu cha - ran.
+ Khao s i t trong khu c h i - rgn: M l i dgt tiln hinh khio s i t 2 cym cha - rgn, moi cum thyc hign 2 mgt c i t vudng gdc vdi nhau di qua vj tri rgn, di0n tfch quan s i t 200m^/MC (5 m x 40 m), thdi gian lgn 40 - 60 phut/MC,
+ Khao s i t xung quanh khu cha - rgn:
Nghien cuu da thyc hign 3 dgt khao sat tai cic vj tri cich cym c h i - rgn gan nhat l i 50m, 100 m v i 150m; ung vdi moi khoang thyc hiin 2 m i t cat; di#n tfch quan sat lOOm'/MC (5 m x 20m) v i thai gian lgn 30 + 40 phut/MC.
- Mgt c i t di>ng (vudng gdc d i y bien): X i c dinh mgt dfl dpng v i t xung quanh h^ thong c h i - rgn
+ Mgt c i t dCrng dugc chia thinh 05 khoing theo chieu cao cha tinh tir d i y bien, Khoang dau tu 0 . 2 m dugc xac djnh mgt dfl theo mat cit ngang nen d mgt c i t dung khdng thyc hipn lgi: con lgi 04 khoang, mdi khoang cd chieu cao 4m. g i m : 2 + 6 m; 6 ^ 10 m, 10 ^ 14 m va tren 14 m.
+ Dien tich tuong ung vdi cac khoang la 25 m^ (5 m X 5 m).
+ T h l tich moi khoang khao s i t tuong ijng I i 1 0 0 m 3 ( 2 5 m ^ x 4 m ) .
48 . TRU6NG DAI HOC NHA TRANG
2.3. Doi tu-ong l<iiao sat ^ ' ' I H D l i tugng khio sat bang phuong F ^ ^ ^
gom c i c loii ca day. c i rgn v i dpng v^t khftfi xuong song (than m l m va da gai) kich it '' du Idn cd the quan s i t trang mat thudng, 3. PhiFO'ng p h i p xi> ly so li$u
Nghien ci>u da su dung cdng aji Descnpttw Statistics cua p h i n mem Microsoft Excel Sw nhim thong v i tinh toan so lipu.
So lieu tinh toan dugc quy ve g i i trj tnjrn binh Vffi dfl tin cay 95%.
So lugng loii b i t gap va m i t dfl tojng M i cua Chung trong cac dgt khao sat dugc tftih cho 400m^ dien tich mat c i t v i 400m3 thl fieh vung nudc
III. K^T QUA NGHIEN CI>U VA T H A O LUA»
1. Thyc trang ngu6n Ip-r t r u o ^ khi xSy d ^
md hinh -^
Qua khao s i t 04 m i t cat theo hudng vufirf gfle vdi bd bien tai khu vyc mui Bin Than 3 lu'gng loai thCiy sinh b i t g i p khdng nhilu, chI45 loii va chCi yeu la nhdm c i vdi 38 loii, cicnhfim' khic khdng ding ke. Tan suit bit gip cic iodi thip, cd tdi 30 loai chl bat ggp 01 lan (cliiSm 66,7%) tong so lan b i t g i p , 7 loai bat g|p tCrS+
5 lan v i s l cdn lgi l i b i t ggp trin 5 lln.
So sanh vdi ket qua khio s i t cua Trjnh Tlii Hilu (2009) da xac djnh dugc 137 loii, oim thay ket qua cua dgt khao s i t n i y cd s l lu(mg loai It hon nhieu, chi 38/137 loii. B l i chilu vdi danh myc thinh phan loii cho thiy: toan bp 38 loii bat ggp hoin t o i n gilng T\haii\i khdng phat hign l o i i n i o ngoii danh mge [1];
Dieu nay t h l hiin rang, cd sy khic nhau triMlEJ thanh phin c i u tmc cua quan x i c i rgn gICK hai thdi diem nghidn cCru va xu t h i biln tfS theo chilu hudng g i i m dan thinh phin lofi theo thdi gian.
Q u i trinh khao s i t da ghi nh§n m$t dO ck loai bat gap, cac l o i i n i y dugc chia IhinlH nhdm chfnh, bao g i m ; nhdm c i , da gal, ttifln m l m va giip x i c . Mat dO cua ti>ng nhdm d u #
t h l hiin d bang 1. ••'•
Jm^hiKhoa hoc - Cong ttf hi Thtjy son
Sti 4/2015
Bang 1, H j t Jp t m n g blnh bat g j p (ea thl;400in') ml kftu virc nghien cCpuK4t qua khao sat cho thay:
- Mat ap ca cao n h i t chiem 91,9% vS trung binh dat 250 ca theMOOm".
- Mat ap cua cac nhom da gai, than mem v4 giSp xac l<ha thap, chiem 8,1%
So s4nh vai \t.k qua Ichao sat nam 2008 da xac ainh du.pc mat do ca ran o khu vi/c mui Ban Than dao dong t i l 295 . 662 ca the/400m«, trung blnh dat 434 ca the/400m" [IJ. Tuy nhiSn!
k i t qua khao sat dffi nay tmng binh m j i do chi dat 250 ca th4/400m'. Dl4u nay cho thjy c6 sv a\ic bi$t v i mat dp phan bo ca ran giOa hai dpi khao sat va da c6 WSn asng theo chiiu huong
giam dan theo thoi gian. Bay cung la mmh chieng the hipn ngu6n toi thuy san a viing bien ven bo da suy giam. Ben c^inh do, cac ioai ca o vung bien khao sat co kich thuoc ca the tuong doi nho, hidm khi b i t gap cac loai hoac a6i tu-ong CO kich thuoc Ion.
2. ThiPC trang nguon Ip-i sau khi xay du'ng mo hinh
2.1. So tuctng toat va tan suat bit gap 2.1.1. Trong khu cha - ran
Qua 5 dot khao sat tai 10 cum cha - ran vol 20 mat cat, so lirpng loai b i t gpp theo nhiSm doi tirpng dirpc thS hian a bang 2. „ „ , luyiiy u,^,/i; llie nie Bang 2. S6 iLfgng loai dong v j t bk gap qua cac dqrt khao sat
Tir bang tren cho thay:
- So lugng loai dpng vat ma chu yeu la cac loai ca trong khu cha - ran tang len theo thai gian xay dvng, thirl gian cang dai thi so luong loai t j p trung co khuynh huong tang len.
- So vol truwc khi xay dung mo hlnh thl sau 5 thang l i p dat so iirp-ng loai tang len 62,2%
(tir 45 ten 73 loai)
- Nhom ca chiem uu the ve so lu-ong, cac loai khac It bat gap hon.
Qua trinh khao sat da ghi nhan duoc lan suat bat gap cac doi tupng trong mat cat. Tan suit bat g j p cang nhieu. mat dp doi tugng cang cao. Ket qua cac dot khao sat duoc the hien o bang 3.
BJng 3. T i n s u i t b i t g j p cac toaiqua cac dot khao sat Thang 7
TAn s u i t bat g j p ll^n)
Ting
TRaONG OAI HOC NHA TRANG . 49
Tap chi Kiioa hoc - Cong nghe Thuy sdn
S64Ti> bang tren cho thay: Tan suit b i t gap cic loii ca trong khu cha - rgn cd chieu hudng t i n g theo thdi gian. Thdi gian cang dai, t i n suat b i t gap cang tang v i giam d i n dfii tugng b i t ggp 01 l i n . Dieu niy cho thiy mat dp cua c i c loii ca t i n g d i n theo thdi gian xiy dyng
*S 50 le 40 I 30 Z 20 10
mo hinh.
2.1.2. Xung quanh khu cha - rgn Qua 3 dgt khao sat tai c i c khu vyc xum quanh vo'i 18 mgt cat d khoang cich SOm 100m, 150m so vdi cac cym c h i - r g n , kitiyjj dugc t h l hien a bieu do 1.
™ 7^
64 I 1 64 64
I—l^Li W^^ B - ^
• ~ T 4 6 • I45 • 47
IIR IIH I I I
T8/2014Thdi gian khao si
Bicu ah I . So l u y n g l o i i b i t gSp theo khoang each xung quanh k h u chft - r^n Tu bieu do tren cho thay:
- G i n khu c h i - rgn s l lugng loai b i t ggp nhieu hon a khu vi^c xa Tuy nhien, so lugng loii xung quanh it hon so vdi vj trf trung tam c h i - rgn (tuong dng 0 m trong bieu d l 1).
- Cl ngoii khu cha - rgn. nhdm c i bien cung chilm uu t h l hon so vdi c i c loii khac.
- So lugng ioii b i t gap xung quanh kliu c h i - rgn cd khuynh hudng t i n g lin theo thdi gian xiydi^ng.
Ben cgnh so lugng, tan suit bat g$p cdc doi tugng d khu vyc xung quanh cQng tang I6n theo thdi gian v i phy thupc v i o khoing cicti den c i c cym c h i - rgn (bang 4).
TT
1 2 3
Bang 4. Tan s i t bat g j p c j c l o j i qua
T i n sudt b i t g$p (lln) 01
2-1-5 tran 5 Tong
T i l i n g 6 SOm
35 17 5 67
100m 40 14 1 55
150m 37 8 1 46
cac d p i k h j o sat T i l i n g 8 SOm
33 24 7 64
loom 41 10 6 57
150m 36 8 1 45
T h i n g 10 SOm
26 23 15 64
100m 39 10 9 58
ISOin 35 11 1 47 Nhu v j y xay dvng cha - ran khong nhung
thu hut cac loai sinh v j l d i n Inj ngu trong vung rpn ma c6n phan bo ra ngoai kha xa. Khi m j t do ca trong khu cha - r?n tang ISn, do nhu cau ve thirc an va khdng gian song tang, chic chin chiing se di cu den cac viing lan c i n de bat moivasinhsing. Oiiu nay cho thay vai tro cua he thing cha - ran trong vijc t j p tning, bao ve,
50 . TRUONG DAI HOC NHA TRANG
tai tao va phat then nguin lpi da dtrpc phjt huy hiju qua.
2.2. M j i d p p h j n b d 2.2.1 Trong khu cha - ran
Qua trinh khao sat da ghi nhjn m j i d j c*i loai b i t gap theo cac nh6m g i m c j , da gal than mem va giap xjc. Tmng blnh m j t d j thao thcri gian khjo sat a m j t c i t ngang dugc Bli hijn tai biiu d i 2.
ISRduKhoa hoc - Cdtte nshi Thtiy .mn
2.000,
«<, f ' « » ,.654 1712 ' - ° ' g
J 1 600 J 1.525 • _ ! ^^m ^ ^
1.294 ^ ^ ^ ^ H ^ ^ 1 ^ ^ 1
I l l j l l l l
ft ' ^ ^ ^ ™ " S 7 T h i n g s Thang 9 Thang 10
K i t qua khao sat cho thiy:
- Mat d i d j n g v j t bat g j p trong khu cha ran tang IJn theo thirl gian xay dirng.
- M j t dp nhdm c j chiim uu t h i ban so vc cac ntiom khac.
- Mtic d i gia tang m j t do cao, tir 1.294
Thang 7 Thang 8 Thang E Thoi gian khao sat Biln d i 2. Biln Mng m|t d , pMn b6 theo IbM gian khio . i t
Bang 5. Mat do trung binh theo t h o i gian k h j o sJt
ian 1.812 ca thi/400m2, tang 40% sau 5 thang xay dung cha - ran va tang 6,7 i j n (tir 272 len 1.812 ca the/400m') so vol Inroc khi thiet lap mo hinh.
Tntng binh mat do phan bo o- mat c i t dirng theo thiri gian khao sat duoc the hi j n t i bang 5.
K i t qua khao sat cho thay:
- Doi vol m j t cat dirng, khong b i t g j p cac loai sinh v j t khac ngoai ca Mat do ca phan bo b mat c i t dung ctJng tang len aang k i , tir 2.148 ien 3.800 ca thi/400m>, mirc dp gia tang li'n, dat tren 77% sau 5 thang xay dung
- M j t dp ca tang l§n a tat ca cac ting nut^c theo chieu cao ciia cha. Trong khoang tir 2 + 14m, m j t d j c j dao dpng khong Ion, kha ding deu nhau o cac khojng khao sat Tuy nhijn, 6- khoang trjn 14m m j t dp giam, d j c bijt la phia tren ba c h j ca phan b i thua thot.
Biiu nay hoan loan phu hop vol dac tinh sinh hpc cua ca bien.
Do tap tlnh smh hpc cua ca Iru ngu o noi c6 bong ram, khi xay dung mo hinh cha - ran (bao gom ca be cha) ca tap Imng xuing cu tru o phia diroi be Do dd, m j t dp c j thl^a d i n tir be cha tro len mat nuoc.
2.2 2. Xung quanh khu cha - rpn Mat d i phan b6 ciia cac lpai dpng vat xung quanh khu cha - ran vol khoang each 50m, 100m va 150m I h i hien qua bleu do 3.
TRl/ONG OAI HOC NHA TRANG . 51
Tap chi Khoa hoc - Cong nghe Thuy s
Thfri gtan khao sdil
Bifn do 3. Bien dgng m^t 3^ d^Dg vSt theo thJii giaa khdo sit K i t qua cho thay:
- Mat dp phan bo c i c loii dpng v i t xung quanh tang theo thdi gian va giam dan theo khdng gian tfnh tu vj tri trung t i m c i c cum cha - rgn (Ufong dng 0 m frong bieu do 3).
- Cing g i n khu cha - rgn, mgt dp phin bd cang cao nhung t h i p hon so vdi ben trong.
- S6 iugng loai va m i t dO phan bo cOa dOng vgt tang len d i n g k i & khu vyc xung quanh so vdi trudc khi xay dgng md hinh.
Hinh 2. Ci IIIBD tien d'ran Hinh 3.
K i t q u i khao s i t cung cho thiy sg xuit hign rong, rdu phit trien tren rgn v i c h i . Rong v i rgu l i mdt nhung m i t xich trong chudi thi>c i n cua nhieu toil sinh v i t bien. Do dd, khi cd rong v i reu se thu hut sinh v i t den tim kiim thfjc an v i d i y cung l i yeu to quan trpng cho c i c loai c i den sinh sing v i phit trien.
Ngoii ra, trdn cic g i i the rgn nhan tao cung da hinh thinh v i phat tnen san ho mem.
Mac du muc dd phit trien cua san ho mem chua Idn nhung l i yeu to bieu thi chit lugng mdl tardng song da dan dugc c i i thipn va l i diiu kign tot de cac loai thuy sinh cu tni, sinh song va phit triin,
Nhu viy, viic xiy dgng mo hinh cd y nghTa quan trpng trong vi#c bao vg v i t i i tgo nguon lgi khdng chi tgi vung bien t h i c h i - rgn ma cdn 6 cic khu vgc xung quanh. Do dd, trien khai ap dyng giii phap ky thugt n i y d viJng bien ven bd se gdp phin c i i thiin chit lugng
52 • TRUONG DAI HOC NHA TI?ANG
Hinh 4. Ci con quanh cfai-rfn mdi trudng song, cung c i p nguin thuc i n , t^o noi sinh cu cho c i c loii sinh vgt biin v i khfli phyc nguon Igi thuy san. Bdn cgnh dd. chi - rgn cdn gdp phin ngan c i n m0t so ngu cy tie ddng t i i u cgc d i n nen d i y hogt d0ng d vOng bien ven bd, g i i m cudng Igc khai thic v i tgo dieu kipn cho cac ioai thuy s i n t i i ket din.
IV. K^T LUAN VA KI^N NGH!
Ket q u i d i n h g i i hi0u qua cua mo hinh Si chi ra ring, m i t dp va thinh phin loii ting I6n trong v i ngoii khu c h i - rgn.
So iugng loii sinh v i t trong khu chi - rgn tang l i n theo thdi gian x i y dgng. So lugng kiSi t i n g len 62,2% (ti> 45 len 73 loii) so vdi trmJc khi x i y dgng mo hlnh.
Cdng vol s6 lugng l o i i t i n g i i n , m|t dJ phan bo cua chung cung tang theo, gip 6,7 l i n so vdi tnj'dc khi xay dgng md hlnh v i tSnfl 40% so vdi thang d i u l i p dgt d mgt c i t ngang, 77% a mat cat durng.
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Tifp chi Khoa hoc - Conf nfhe Thtiy sati S i iuyng loai dpng v j t khing chi tang len ft khu cha - ngn ma con ft cJc khu vuc xung quanh.
Mat dp phan bp xung quanh khu cha - ran ciing autre tang I j n aang k i va cti khuynh huftng tang theo thfti gian x j y dung.
Phat Iriin cha - ran ft vung bien ven bft se gftp phan tich a r c nham bao v j , phat then nguin ip'l thuy san va han che diryc m j t s i IPSi ngtr cg vl phgm ving nuoc hoat dpng.
S6 4/2015 B j n canh do, nghien ciru con cung c i p d i n iieu khpa hpc quan ttpng cho nha q u j n 1^ ap dung giai phap ky thujt trpng cong t j c khil phuc ngucn Ip-i vap thirc t i l n san xuit.
Trjn CO sft k i t qua nghien cuu oo the trien khai ap dung cha - ran o vung bien ven bft, khu virc CO cac diiu kijn tuong d i n g chic chan se mang lai hieu qua cao trong cong tac bap ve va phat trien nguin lol thuy san.
T A I LIEU THAM KHAO Tting Vlfl
Ph6.gN6„g ngltlft, , i PMt thin Na„g tl,6„ huyen Ni, ThM, B.o c.„ t6„g kh san xMt nang ngh.p nH™
TiingAnh
Da,t„ai,Ala„AJ,a.dMa„i„ MS J„n.s,,986.A™nal„fs„,vey methods f o r l i „ . g ™ „ ™ „ c „ . s . , l areas
TRUaUG OAI HOC NHA TI5ANG .
