I.Tai nguyen hai san

Cung cap nguon thuc pham quan trong cho con nguoi moi vung nuoc co mot rtru luong toi da nhat dinh muc khai thac vuot muc tai sinh dan den can kiet khi can kiet hoan taon hay con goi la tuyet chung thi ko co kn khoi phuc lai nhu truoc nang suat tai sinh va tru luong trong vung phu thuoc lon vao dieu kien moi truong muc khai thac cua con nguoi nhu cau ngay cang tang cao va giá tang .quan li nganh khai thac hai san rat phuc tap do dia ban qua rong

II.KHAI THAC TOI UU TAI NGUYEN HAI SAN

Theo hinh 5.1 thi truc tung bieu hien tru luong cua mot loai ca nhat dinh nao do (so con ,tan, or sinh khoi )truc hoanh bieu thi thoi gian

Xmin la diem tru luong nguong ,noi co the xay ra hai truong hop

+tru luong Xmin la tru luong toi thieu cua mot loai co kha nang loai do ko the tang truong so luong ma giam dan va di den tuyet chung

+Xmin co the tang truong dan len gia su ko co su danh bat hoac dich benh lon den muc do nao do thi tang truong nhanhh dan ,boi so luong thuc an nhieu trong moi truong luong oxy du va cac dieu kien song khac dam bao.sau do tang truong se cham dan bo tru luong dong thuc an dan ko du cac dieu kien song khac ko du theo thoi gian den mot tru luong Xmax =K .su tang truong se ko con nua tru luong dung lai muc tang truong = 0

+Xmax co the hieu tru luong can bang tu nhien khoang(0,Xmin)la laoi dang o giai doan nguy co bi tiet chung cua laoi khoang (Xmin ,Xmax)la giai doan bien dong tru luong cua loai

Hinh 5.2 o diem Xmsy goi la nang suat ben vung toi da do la khi muc do tang truong dat d\cao nhat co the thu hoach ca o muc tang truong cao nhat nay co the dat toi uu san luong nhung chua toi uu ve kinh te

2.khai thac toi uu

a.no luc danh bat E(effort)san luong danh bat y(yield)

so luong phuong tien danh bat nhu tau thuyen luoi ... duov\c quy thanh don vi chuan danh bat vi du tau 100cv +10 kmluoi = 1 don vi no luc danh bat (E=1)

khai niem nay the hien kha nang ,quy mo danh bat cang lon thi san luong khai thac cang nhiue neu tru luong ca o bien la van lon

nhu vay:E=X/Y hay Y=E.X

trong do E : la no luc Y:la muc khai thac/san luong danh bat X :tru luong tai nguyen

hinh 3.3 cho thay tru luong ca cang lon thi san luong danh bat se teng dan khi san luong dat Xmsy (tuc muc tang truong cao nhat )thi san luong danh bat se giam dan

diemXcc toc do tang truong =0 tuc sinh ra = tu vong ,san luong ko tang them neu danh bat o day thi san luong danh bat se lam tru luong giam

giau tru luong va quy mo no luc danh bat co quan he ngich no luc danh bat tang thi tru luong ca se giam

no luc danh bat toi da E max se giam dan den qyu mo khai thac wa muc

khai thac o muc san luong Ymsy or Emsy la dat duoc nang suat ben vung toi da

vi du :khi muc san luong cua mot vung bien Xmsy =k=500 muc tang truong luc do la 20% san luong khai thac toi da ben vung =Ymsy =500.0,2=100

tuy nhien duuoi goc do klinh te no chua phai la toi uu kinh te vi cac yeu to chi phi doanh thu va loi nhuan chua dc can nhac den

b.toi uu kinh te cho klhai thac

de xd muc danh bat toi uu kinh te doanh thu =san luong .gia ban (gia su gia ban ko thay doi)

vay doanh thu co danggong duong san pham luong thu hoach rheo san luong

loi nhuan = doanh thu - chi phi

toi da hoa loi nhuan se la toi da khoang cach gia doanh thu va chi phi do la diem no luc danh bat Eprof

diem Eprof<Eemsy

diemEoa la diem danh bat ko co loi nhuan va diem nay dc goi la diem tu do tip can hay khai thac tu do sau diem nay khai thac nay bi lo nhieu nguoi se roi khoi nganh truoc diem nay co loi nhuan duong nen se co nhieu nguoi tham gia(hinh3.5)

3.bi kich ve cua chung

Neu no luc toi da Eoa trung voi tru luong toi thieu se dan den su tuyet chung cua laoi

Neu duong TC cang co toc do thap thi Eoa cang de trung voi tru luong topi thieu dan den nguy co tuyet cung cang cao nhu laoi voi chau phi voi muc chi phi san bat rat thap

Nhung nguy co dan den can kiet tai nguyentai sinh hoac su tuyet chung laoi tren do su danh bat khai thac tu do tai nguyen chung

+ko co chu so huu cu the

+Thieu qaun li va pap luat bao ve

+danh gia gia tri tai nguyen thap

4.thoi gian va chiet khau

Quy tac xac dinh thoi diem toi uu thu haoch

Toc do tang truong sinmh hc+toc do tang truong gia tri von=suat chiet khau

Toc do tang truong sinh hoc cua ca la su tang trong luong cua tru luong ca

Toc do tang truong von la hieu suat cua von neu gia ca tang len theo time

Xac dinh gia tri tong thu nhap cho thu hoach o thoi gian tuong lai= tru luonghien tai +tru luomh tang them).gia tuong lai

Quy gia tri nay ve hien tai bang cong thuc Pvdem so sanh voi tong gia tri thu hoach ca hien tai ,thoi diem nao co gia tri cao hon se dc thu hoach

III.chih sach danh bat

so huu tai san :ca nhan hay tap the cong cong ->danh bat se ko con tu do tip can->khai thac Eprof

chinh sach quan li

cap phep so luong tau thuyen danh bat(han ngach tau thuyen)->Eprof

cap phep han ngach san luong (thuong la ti le %cho moi ngu dan)danh bat

thue danh vao ssan luong(it dc ua chuong then the gioi)

quy dinh cac phuong tien danh pat(cam loi cao luoimat nho .dung dien,anh sang.chat no,hoa chat,,,)