Jahilci Ba Ni'ima Ba Ne: Sabon Bincike Akan Matsayin Hannun Kayayyakin Kifin da Ba a Tantance Su Ya Nuna Barazana Ba A Duniya Ta Hanyar Kifi.

Kenneth Stump, Fellow Policy Fellow a The Ocean Foundation

Fiye da kifaye (da kuma amfani da kayan kamun kifi masu lalata) ana yawan ambaton su a matsayin ɗaya daga cikin manyan barazana biyu ga dabbobi a cikin teku. Fiye da kifaye yana faruwa ne lokacin da kifin ya cire kifin daga yawan jama'a cikin sauri fiye da yadda yawan jama'a ke iya cika kansa - a wata kalma, kifin ya wuce kima. Idan ba a hanzarta sarrafa shi ba, wuce gona da iri yana haifar da raguwar kifin da kuma rugujewar kifin. Masana kimiyya da manajojin kamun kifi sun yi ƙoƙari su gano yadda ya kamata a ce yawan al’ummar kowane nau’in jinsin bai wuce kifaye ba.

Don ingantattun hannun jari waɗanda aka tantance ta kimiyance, ana iya ƙididdige matsayin haja dangane da sharuɗɗan kifin da suka dogara kan iyawar da aka bayar don samar da matsakaicin yawan amfanin ƙasa mai dorewa (MSY). Yin amfani da waɗannan matakan al'ada na dorewar kamun kifi, Dr. Boris Worm et al. (2009) ya gano cewa kashi 63% na kifin kifin da aka tantance a duk duniya suna da girman kiwo ("biomass," wanda aka nuna a matsayin "B") a ƙasa da matakin da aka kiyasta zai samar da MSY (B/Bmsy <1), yayin da wani bincike daban ta hanyar. FAO (2010) ta kammala cewa kashi 32% na hannun jarin da aka kiyasta a duniya sun fi kifin (B/Bmsy <0.5).

A taƙaice, yawancin kifin da aka tantance a duniya gabaɗaya ne ko kuma an yi amfani da su sosai. Amma kawai ~20% na kama kifi na duniya (bayanan saukar saukar ruwa) sun fito ne daga nau'ikan da aka tantance. Menene game da matsayin dubban matalautan kifin da ba a tantance ba, wanda ke da kashi 80% ko fiye na abin da ake kamawa a duniya kowace shekara?

Christopher Costello na UC Santa Barbara da abokan aikinsa sun buga wani sabon bincike na matsayin jari-hujja na duniya a cikin bugu na Kimiyya ta kan layi (Satumba 27, 2012). Yin amfani da bayanan saukowa da hanyoyin tantancewa kai tsaye, marubutan sabon binciken sun kammala cewa yawancin kifin kifin na iya raguwa sosai kuma suna raguwa sosai:

Kashi 64% na hannun jarin kifin da ba a tantance ba suna da jarin halittun da ke ƙasa da Bmsy (B/Bmsy <1), wanda ke daidai da raguwar adadin akan tsari na 60-70% na yawancin hannun jari.
Kashi 18% na hannun jari da ba a tantance ba sun rushe (B/Bmsy <0.2) - matakin raguwa sosai ta yadda yawan kifin na iya zama ɗan ƙaramin juzu'i na yanayinsa, girman da ba a kifa ba.

Matsayin ƙarancin kifaye da yawa (ƙananan B/Bmsy) yana da sakamako ga wadatar abinci: amfanin kifin ya yi ƙasa da yuwuwarsu idan an bar hannun jari ya murmure zuwa matakin da, a ra'ayi, zai samar da MSY. Tun da yawancin kifin da ba a tantance ba suna cikin matalauta da ƙasashe masu tasowa, hanyoyin gudanarwa don sake gina hannun jari waɗanda suka dogara da ingantaccen shugabanci da ikon sa ido ba zai yi aiki ba. Amma Costello da abokan aikinsa suma suna da bege cewa sabbin dabarun da suka haɗa haƙƙin masu amfani da yanki (TURFs), ƙungiyoyin kamun kifi, da wuraren da ba a kula da ruwa ba na iya dawo da waɗannan al'ummomin zuwa mafi koshin lafiya, matakan samar da albarkatu - idan an ɗauki matakin gaggawa don dawo da koma baya. .

A {asar Amirka, gyare-gyare ga dokar kamun kifi a 1996 da 2006, ya rage yawan kifin da aka tantance, da kusan rabin tun lokacin da Hukumar Kamun Kifin Ruwa ta {asa ta fara ba da rahoton matsayin shekara a ƙarshen 1990s, kamar yadda aka nuna a cikin siffa 1. A 2011, {asar Amirka. Kamun kifi na kasuwanci ya sami kamun kifi mafi girma cikin shekaru 17, wanda ke nuni da cewa yunƙurin hana kifin da sake gina kamun kifi ya fara samun riba a yankuna da yawa (amma ba duka) na ƙasar ba.

Amma kusan rabin duk hannun jarin da aka sarrafa a cikin ruwan Amurka har yanzu ba a tantance su ba kuma binciken Costello et al. ya gano cewa wasu daga cikin wadanan hannayen jarin da ba su da kyau za su kasance cikin mummunan yanayi kamar na kasashe masu tasowa. Alal misali, yawancin kifayen ruwa irin su rukuni a Kudancin Atlantic da Gulf of Mexico, yawancin nau'o'in sharks, halibut a New England, don sunaye, an san cewa sun ƙare a tarihi duk da cewa ba a tantance su ba.

Tasirin kifin da yawa bai iyakance ga raguwar nau'ikan kifayen guda ɗaya ba. Cutar da nau'ikan nau'ikan nau'ikan kasuwanci a cikin sauri mai nasara na iya haifar da caschic caschic wanda ke canza tsarin abincin abinci a lokaci, ƙirƙirar sakamakon da ba a kula ba ,. Abubuwan da ke haifar da kifin kifaye ba safai ake la'akari da su ba a cikin lissafin al'ada na kifin kifin, amma wani bincike na baya-bayan nan da Cibiyar Kimiyyar Kifi ta Arewa maso Gabas ta NOAA ta yi ya kammala da cewa yankin New England ya fuskanci kifin kifin da ya haifar da tartsatsin kifin da nau'ikan zababbun tsarin girbi da suka samu. ya haifar da sauyi a tsarin al'ummar kifaye daga tsarin da nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan cod ke mamayewa zuwa wanda ke ƙara mamaye ƙananan kifayen kifaye masu ƙarancin ƙima irin su herring da nau'in elasmobranch (kananan sharks da skate). An lura da irin wannan tasirin a cikin wasu halittun ruwa masu kifin, kamar Tekun Arewa ta Turai ko murjani reefs na Caribbean.

Kamar yadda sabon binciken Costello et al. ya nuna, a zahiri dubban nau'ikan kamun kifi ne ke shafar su a duk duniya kuma galibi suna fuskantar raguwa. Ba a san sakamakon da ba a yi niyya ba na irin wannan tasirin da ke yaɗuwa a kan yanayin ruwa, amma jahilci ba ni'ima ba ne. Fiye da kifaye na barazana ga samar da abinci da tattalin arzikin kamun kifi na cikin gida, amma yunƙurin dorewar samar da kifin daji a matsayin abinci ga ɗan adam ba zai yi nasara ba idan muka yi watsi da ayyukan da duk waɗannan nau'ikan ke takawa a cikin yanayin muhalli. . Yayin da masana kimiyar kifi da manajoji ke kokawa kan hanyoyin kawo karshen bala'in kamun kifin, dole ne su sanya wadannan la'akari da yanayin muhalli cikin lissafinsu na yawan kamun kifin da ya yi yawa. Yana iya nufin kama kifi kaɗan, amma madadin na iya zama babu kifi kwata-kwata.

Sources:

Christopher Costello, Daniel Ovando, Ray Hilborn, Steven D. Gaines, Olivier Deschenes, da Sarah E. Lester (2012), Matsayi da Magani ga Kifin da ba a tantancewa a Duniya, Kimiyya kan layi, Satumba 27, 2012.

Cibiyar Kimiyyar Kamun Kifi ta Arewa maso Gabas ta NOAA (2009), Rahoton Matsayin Halittu na NE Continental Shelf Large Marine Ecosystem.

Boris Worm et al. (2009), Sake Gina Kifin Duniya, Kimiyya 325: 578-585.