Ukungazi Akuyona Injabulo: Ucwaningo Olusha Ngesimo Sezinhlanzi Ezingahloliwe Lugcizelela Usongo Lomhlaba Wonke Olubangelwa Ukudoba Ngokuqile.

nguKenneth Stump, Umlingani Wenqubomgomo Yasolwandle e-The Ocean Foundation

Ukudoba ngokweqile (kanye nokusetshenziswa kwezinto zokudoba ezibhubhisayo) kuvame ukushiwo njengenye yezinsongo ezimbili ezinkulu ezilwaneni olwandle. Ukudoba ngokweqile kwenzeka lapho indawo yokudoba isusa izinhlanzi kubantu ngokushesha kunokuba inani labantu likwazi ukuzigcwalisa ngokwalo - ngegama nje, ukudoba ngokweqile kuwukudla ngokweqile. Uma kungalawuleki ngokushesha, ukudoba ngokweqile kuholela ekuqothulweni kwenani lezinhlanzi ekugcineni nasekuweni kwemboni yokudoba. Ososayensi nabaphathi bezindawo zokudoba balwela ukuhlonza ukuthi inani labantu banoma yiluphi uhlobo oluthile kufanele libe likhulu kangakanani ukuze bathi azidotshwa ngokweqile.

Ezitokisini ezifundelwe kahle ezihlolwe ngokwesayensi, kungenzeka ukuhlola isimo sesitoko ngokuhambisana nenqubo yokudoba ngokweqile okusekelwe ekhonweni lesitoko esinikeziwe ukukhiqiza isivuno esiphezulu esimeme (MSY). Esebenzisa lezi zinyathelo ezivamile zokusimama kwezokudoba, uDkt. Boris Worm et al. (2009) bathole ukuthi u-63% wezinhlanzi ezidotshwayo emhlabeni wonke ezinosayizi wesitokwe sokuzalanisa (“biomass,” oshiwo ngokuthi “B”) ngaphansi kwezinga elilinganiselwa ukukhiqiza i-MSY (B/Bmsy <1), kanti ucwaningo olwehlukile olwenziwe i-FAO (2010) yaphetha ngokuthi u-32% wezitoko ezihlolwe emhlabeni jikelele zidotshwa ngokweqile (B/Bmsy <0.5).

Kafushane, iningi lezinhlanzi ezihloliwe emhlabeni wonke zixhashazwa ngokugcwele noma ngokweqile. Kodwa kuphela ~ 20% wezinhlanzi ezidotshwa emhlabeni wonke (ukwehla okubikiwe) okuvela ezinhlotsheni ezihloliwe. Kuthiwani ngesimo sezinkulungwane zezinhlanzi ezingenalwazi, ezingahlolwanga ezibalelwa ku-80% noma ngaphezulu wokudotshwa kwezinhlanzi zasolwandle emhlabeni wonke minyaka yonke?

U-Christopher Costello we-UC Santa Barbara kanye nozakwabo basanda kushicilela ucwaningo olusha lwesimo sesitoko esimpofu kakhulu sedatha kuhlelo lwe-inthanethi lweSayensi (Septhemba 27, 2012). Besebenzisa amarekhodi atholakalayo okufika kanye nezindlela zokuhlola ezingaqondile, ababhali bocwaningo olusha baphetha ngokuthi iningi lalezi zinhlanzi cishe zizophela kakhulu futhi zehle kakhulu:

U-64% wezindawo zokudoba ezingakahlolwa zinenani elingaphansi kwe-Bmsy (B/Bmsy <1), elilingana nezinga lokuncipha ngohlelo luka-60-70% ezitokisini eziningi.
U-18% wezitokwe ezingahloliwe ziyawa (B/Bmsy <0.2) – izinga lokuncipha kakhulu kangangokuthi inani lezinhlanzi lingase libe ingxenye encane nje yobukhulu bayo bemvelo, obungadotshwanga.

Isimo sokuncipha kwenani lezinhlanzi eziningi (i-B/Bmsy ephansi) sinemiphumela ekuvikelekeni kokudla: isivuno sokudoba singaphansi kakhulu kwamandla azo uma isitokwe sivunyelwe ukuba sibuyele ezingeni elizokhiqiza i-MSY. Njengoba eziningi zalezi zindawo zokudoba ezingahloliwe zisemazweni ampofu nasathuthuka, izindlela zokuphatha zokwakha kabusha amasheya athembele ekubuseni okuqinile nasemandleni okuqapha ngeke zisebenze. Kodwa u-Costello nozakwabo baphinde babeke ithemba lokuthi amasu amasha ahlanganisa amalungelo abasebenzisi bezindawo (TURFs), imifelandawonye yokudoba, kanye nezindawo ezivikelwe zasolwandle ezingathathwa zingabuyisela lezi zizwe emazingeni anempilo, akhiqiza kakhudlwana - uma kuthathwa izinyathelo ezisheshayo ukuhlehlisa ukwehla. .

E-US, ukuguqulwa komthetho kazwelonke wezokudoba ngo-1996 no-2006 kwehlise ukudoba ngokweqile esitokweni esihloliwe cishe ngesigamu kusukela i-National Marine Fisheries Service yaqala ukukhipha imibiko yesimo sonyaka ngasekupheleni kwawo-1990, njengoba kukhonjisiwe ku-Fig. 1. Ngo-2011, e-US abadobi bezohwebo baqophe izinhlanzi eziningi kakhulu eminyakeni eyi-17, okuphakamisa ukuthi imizamo yokunqanda ukudotshwa ngokweqile kanye nokwakha kabusha izinhlanzi ezidotshwe ngokweqile isiqala ukuthela izithelo ezifundeni eziningi (kodwa hhayi zonke) zezwe.

Kodwa cishe isigamu sazo zonke izitoko eziphethwe emanzini ase-US namanje azikahlolwa futhi ucwaningo olwenziwa ngu-Costello et al. ithola ukuthi ezinye zalezi zitoko ezingenalwazi kungenzeka zibe sesimweni esibi njengalezo ezisemazweni asathuthuka. Isibonelo, izinhlanzi eziningi zamadwala ezifana namaqoqo e-South Atlantic naseGulf of Mexico, izinhlobo eziningi zoshaka, i-halibut eNew England, uma sibala ezimbalwa, zaziwa ngokuthi ziphelile ngokomlando nakuba zingakahlolwa ngokusemthethweni.

Imiphumela yokudoba ngokweqile ayigcini nje ngokuwohloka kohlobo ngalunye lwezinhlanzi. Ukuncipha kwezinhlobo ezibalulekile zezentengiselwano ngokulandelana ngokushesha kungabangela ama-trophic cascades ashintsha ukwakheka kwewebhu yokudla ngokuhamba kwesikhathi, okudala imiphumela engahlosiwe,. Imiphumela yemvelo yokudoba ngokweqile ayivamile ukucatshangelwa kakhulu ekubalweni okujwayelekile kokudoba ngokweqile, kodwa okunye ukuhlaziya kwakamuva kwe-NOAA's Northeast Fisheries Science Center kuphethe ngokuthi isifunda saseNew England siye sabhekana nokudoba ngokweqile kwe-ecosystem ngenxa yokusabalala kokudoba ngokweqile kanye namaphethini okuvuna okukhethwa kwezinhlobo zezilwane okuye. kubangele uguquko ekwakhekeni komphakathi wezinhlanzi ukusuka ohlelweni olubuswa yizinhlobo zezinhlanzi ezinjengama-cod kuya kokwandayo okubuswa izinhlanzi ezincane ze-pelagic ezinenani eliphansi njenge-herring nezinhlobo ze-elasmobranch (oshaka abancane nama-skates). Imiphumela efanayo iye yabonwa kwezinye izindawo zasolwandle ezidotshwa kakhulu, njengeNorth Sea yaseYurophu noma izixhobo zamakhorali zaseCaribbean.

Njengocwaningo olusha olwenziwe nguCostello et al. imibukiso, izinkulungwane zezinhlobo zezinto eziphilayo zithintwa ukudoba emhlabeni wonke futhi eziningi zibonakala zincipha. Imiphumela engahlosiwe yomthelela osabalele kangaka endaweni ezungezile yasolwandle akwaziwa ngokugcwele, kodwa ukungazi akuyona intokozo. Ukudoba ngokweqile kusongela ukuvikeleka kokudla kanye nezomnotho wendawo yokudoba, kodwa imizamo yokusekela ukukhiqizwa kwezinhlanzi zasendle njengokudla kwabantu iyohluleka uma singazinaki izindima ezifezwa yizo zonke lezi zilwane endaweni ezungezile. . Njengoba ososayensi bezokudoba kanye nabaphathi bebhekana nezindlela zokuqeda uhlaya lokudoba ngokweqile, kufanele bacabangele lokhu kucabangela kwemvelo ekubaleni kwabo ukuthi ukudoba kungakanani. Kungase kusho ukubamba izinhlanzi ezimbalwa, kodwa okunye kungase kube ukungabambi nhlobo izinhlanzi.

Imithombo:

UChristopher Costello, uDaniel Ovando, uRay Hilborn, uSteven D. Gaines, u-Olivier Deschenes, no-Sarah E. Lester (2012), Isimo Nezixazululo Zezindawo Zokudoba Ezingahloliwe Emhlabeni, Isayensi Ku-inthanethi, Septhemba 27, 2012.

I-NOAA Northeast Fisheries Science Center (2009), Umbiko Wesimo Se-Ecosystem we-NE Continental Shelf Large Marine Ecosystem.

U-Boris Worm et al. (2009), Ukwakha Kabusha I-Global Fisheries, Isayensi 325: 578-585.