Ukungazi akuyonwabisi: Uphononongo olutsha malunga neSimo soShishino lweeNtlanzi olungavavanywanga lugxininisa isoyikiso sehlabathi esibangelwa kukuloba ngokugqithisileyo.

nguKenneth Stump, uMlingane woMgaqo-nkqubo woLwandle kwi-Ocean Foundation

Ukuloba ngokugqithisileyo (kunye nokusetyenziswa kwezixhobo zokuloba ezonakalisayo) kudla ngokuchazwa njengenye yezoyikiso zimbini ezinkulu kwizilwanyana elwandle. Ukuloba ngokugqithisileyo kwenzeka xa ushishino lokuloba lususa intlanzi kubemi ngokukhawuleza kunokuba uluntu lunokuzizalisa ngokwalo - ngelizwi nje, ukuloba ngokugqithisileyo kugqithise. Ukuba akulawulwa ngokukhawuleza, ukuloba ngokugqithisileyo kukhokelela ekuphelisweni kwesitokhwe sentlanzi ekugqibeleni nasekuweni kweshishini lokuloba. Oosonzululwazi kunye nabaphathi bezokuloba bazama ukuchonga ukuba bangakanani na inani labemi bazo naziphi na iintlobo zeentlanzi ukuze bathi akulotywa ngokugqithisileyo.

Kwizitokhwe ezifundwe kakuhle eziye zavavanywa ngokwenzululwazi, kuyenzeka ukuvavanya ubume besitokhwe ngokumalunga neendlela zokuloba ngokugqithisileyo ezisekelwe kubuchule besitokhwe esinikiweyo sokuvelisa isivuno esizinzileyo esiphezulu (MSY). Esebenzisa le milinganiselo yesiqhelo yokuzinza koshishino lokuloba, uGqr. Boris Worm et al. (2009) yafumanisa ukuba i-63% yezabelo ezilotyiweyo kwihlabathi jikelele zinesayizi yemfuyo ezalanisayo (“biomass,” echazwa njenge “B”) ngaphantsi kwenqanaba ekuqikelelwa ukuba livelisa iMSY (B/Bmsy <1), ngelixa uphononongo olwahlukileyo lwenziwa. I-FAO (2010) igqibe kwelokuba i-32% yesitokhwe esivavanyiweyo kwihlabathi jikelele silotywe ngokugqithisileyo (B/Bmsy <0.5).

Ngokufutshane, uninzi lwesitokhwe sentlanzi esivavanyiweyo kwihlabathi sixhatshazwe ngokupheleleyo okanye sixhatshazwe ngokugqithisileyo. Kodwa kuphela ~ 20% yokubanjiswa kweentlanzi kwihlabathi (ingxelo yokufika) evela kwiintlobo ezivavanyiweyo. Kuthekani ngemeko yamawaka eentlanzi ezihlwempuzekileyo, ezingavavanywanga ezithatha i-80% okanye ngaphezulu kokulotywa kwentlanzi emhlabeni wonke minyaka le?

UC Santa Barbara kaChristopher Costello kunye noogxa bakhe basanda kupapasha isifundo esitsha sesimo se-data-data-poor stocks kwi-intanethi yeSayensi (ngoSeptemba 27, 2012). Besebenzisa iirekhodi ezifumanekayo zokumisa kunye neendlela zovavanyo olungathanga ngqo, ababhali bophononongo olutsha bagqibe kwelokuba uninzi lwezi zitokhwe zentlanzi kusenokwenzeka ukuba ziphelelwe kakhulu kwaye zehle kakhulu:

I-64% yezabelo zamashishini okuloba ezingavavanywanga zinezityalo ezingaphantsi kwe-Bmsy (B/Bmsy <1), ezilingana nezinga lokuncipha ngokomyalelo we-60-70% kuninzi lwesitokhwe.
I-18% yezitokhwe ezingavavanywanga ziwile (B / Bmsy <0.2) - inqanaba lokunciphisa kakhulu kangangokuba inani leentlanzi linokuba liqhekeza elincinci lendalo, elingabanjwanga.

Imo yokuncipha kwenani leentlanzi ezininzi (i-B/Bmsy ephantsi) ineziphumo kukhuseleko lokutya: izivuno zokuloba zingaphantsi kakhulu kwamandla azo ukuba izitokhwe bezivunyelwe ukuba zibuyele kwinqanaba eliya kuthi, ngokwethiyori, livelise iMSY. Kuba uninzi lwala mashishini okuloba angavavanywanga akumazwe ahlwempuzekileyo nasaphuhlayo, iindlela zolawulo zokwakha ngokutsha izitokhwe ezixhomekeke kulawulo oluluqilima namandla okubeka iliso akunakwenzeka ukuba zisebenze. Kodwa uCostello kunye noogxa nabo banethemba lokuba izicwangciso ezintsha ezidibanisa amalungelo abasebenzisi bommandla (TURFs), ookopolotyeni, kunye neendawo ezikhuselweyo zaselwandle zingabuyisela aba bantu kumanqanaba asempilweni, anemveliso ngakumbi- ukuba kuthatyathwe inyathelo elikhawulezayo ukubuyisela umva ukwehla. .

E-US, uhlaziyo kumthetho wezokuloba wesizwe ngo-1996 no-2006 lunciphise ukuloba ngokugqithisileyo kwisitokhwe esihloliwe malunga nesiqingatha ukususela oko iNkonzo yeSizwe yokuLoba eLwandle yaqala ukukhupha iingxelo zobume bonyaka ekupheleni kweminyaka yoo-1990, njengoko kubonisiwe kumfanekiso woku-1. Ngo-2011, e-US ushishino lokuloba lulolona luphezulu lokuloba kwiminyaka eli-17, nto leyo ecebisa ukuba iinzame zokunqanda ukuloba ngokugqithisileyo kunye nokwakha kwakhona izitokhwe ezilotywe ngokugqithisileyo ziqalisa ukuhlawula kwiindawo ezininzi (kodwa hayi zonke) zelizwe.

Kodwa malunga nesiqingatha sazo zonke izitokhwe ezilawulwayo emanzini ase-US azikavavanywa kwaye isifundo nguCostello et al. ifumanisa ukuba ezinye zezi zitokhwe zihlwempuzekileyo zinokuba kwimeko embi njengezo zikumazwe asakhasayo. Ngokomzekelo, iintlanzi ezininzi ze-reef ezifana ne-groupers kuMzantsi we-Atlantiki kunye ne-Gulf yaseMexico, iintlobo ezininzi zookrebe, i-halibut eNew England, ukukhankanya ezimbalwa, ziyaziwa njengembali ziphelile nangona zingavavanywanga ngokusemthethweni.

Imiphumo yokuloba ngokugqithisileyo ayipheleliselwanga kukuncipha kohlobo ngalunye lwentlanzi. Ukuncipha kweentlobo ezixabisekileyo zentengiso ngokulandelelana ngokukhawuleza kunokubangela i-trophic cascades etshintsha isakhiwo sewebhu yokutya ngokuhamba kwexesha, ukudala iziphumo ezingalindelekanga,. Iziphumo zezinto eziphilayo zokuloba ngokugqithisileyo azifane zinikwe ingqwalaselo eninzi kwicalculus eqhelekileyo yokuloba ngokugqithisileyo, kodwa olunye uhlalutyo lwamva nje lweZiko leSayensi yokuLoba eliseMntla-mpuma ye-NOAA lwagqiba kwelokuba ummandla waseNew England ufumene i-ecosystem yokuloba ngokugqithisileyo ngenxa yokuxhaphaka kokuloba ngokugqithisileyo kunye neepateni zokuvuna ezikhetha iintlobo-ntlobo eziye. kubangele inguqu kubume boluntu lwentlanzi ukusuka kwinkqubo elawulwa zizinto ezinje ngecod ukuya kwenye eyandayo yonganyelwe ziintlanzi ezincinci zepelagic ezinexabiso eliphantsi ezifana neherring kunye neentlobo ze-elasmobranch (ookrebe abancinci kunye nezityibilizi). Imiphumo efanayo iye yabonwa kwezinye iindawo zaselwandle ezilotywa kakhulu, ezifana noLwandle oluMntla lwaseYurophu okanye uqaqa lwe-coral lweCaribbean.

Njengoko isifundo esitsha nguCostello et al. ibonisa, ngokoqobo amawaka eentlobo achatshazelwa kukuloba ehlabathini lonke yaye uninzi lubonakala luncipha. Iziphumo ebezingalindelekanga zempembelelo exhaphake ngolu hlobo kwi-ikhosistim yolwandle akwaziwa ngokupheleleyo, kodwa ukungazi ayilolonwabo. Ukuloba ngokugqithisileyo kubeka emngciphekweni ukhuseleko lokutya kunye noqoqosho lokuloba lwasekuhlaleni, kodwa iinzame zokugcina ukuveliswa kweentlanzi zasendle njengokutya kwabantu ziya kusilela ukuba siyayityeshela indima esebenzayo edlalwa zizo zonke ezi ntlobo kwi-ecosystem. . Njengoko izazinzulu zezokuloba kunye nabaphathi bezamana neendlela zokuphelisa isibetho sokuloba ngokugqithisileyo, kufuneka baqwalasele ezi ngqwalasela zendalo kwizibalo zabo zokuba ukuloba kuninzi kangakanani na. Kusenokuthetha ukubambisa iintlanzi ezimbalwa, kodwa enye indlela isenokuba kukungabambisa iintlanzi kwaphela.

Imithombo:

UChristopher Costello, uDaniel Ovando, uRay Hilborn, uSteven D. Gaines, u-Olivier Deschenes, kunye noSarah E. Lester (2012), iSimo kunye nezisombululo kwiiFisheries zeHlabathi ezingaVavanywanga, iSayensi kwi-Intanethi, ngoSeptemba 27, 2012.

NOAA Northeast Fisheries Science Centre (2009), Ecosystem Status Report for the NE Continental Shelf Large Marine Ecosystem.

Boris Worm et al. (2009), uKwakha kwakhona i-Global Fisheries, iSayensi 325: 578-585.