Editing IPCC:AR6/WGII/Chapter-3 (section)

=== 3.5.3 Food Provision ===

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Globally, about 17% of humans’ average per capita intake of animal protein in 2017 came from marine and freshwater wild-caught and aquacultured aquatic animals ( [[#Costello--2020|Costello et al., 2020]] ; [[#FAO--2020a|FAO, 2020a]] ). Per capita intake of seafood is 50% or more in some Small Island Developing States (SIDS) ( [[#Vannuccini--2018|Vannuccini et al., 2018]] ), and consumption per capita is 15 times higher in Indigenous Peoples than non-Indigenous Peoples ( [[#Cisneros-Montemayor--2016|Cisneros-Montemayor et al., 2016]] ). Fishery products also supply critical dietary micronutrients worldwide ( [[#3.5.4.1|Section 3.5.4.1]] ; [[#Hicks--2019|Hicks et al., 2019]] ; [[#Vianna--2020|Vianna et al., 2020]] ). Marine and freshwater fisheries and aquaculture provide livelihoods for an estimated 10–12% of the world’s population ( [[#Barange--2018|Barange et al., 2018]] ). Fishing and aquaculture provide women and their families with substantial amounts of food and income ( [[#Harper--2020b|Harper et al., 2020b]] ), because at least 11% of small-scale fishers ( [[#Harper--2020b|Harper et al., 2020b]] ) and up to half of all fishery and aquaculture workers ( [[#FAO--2018|FAO, 2018]] ) are women. This section assesses how climate-driven alterations of the abundance or nutritional quality of food from the sea could affect humans. Aquaculture, catch potential changes and human adaptations to changes in wild and cultured harvests are assessed in [[IPCC:Wg2:Chapter:Chapter-5#5.9|Section 5.9]] .

Ocean and coastal fauna are moving towards higher latitudes globally due to warming ( ''high confidence'' ) ( [[#3.4.3.1|Section 3.4.3.1]] ; Table 3.26), challenging fishers and fisheries management ( ''high confidence'' ) as fishers also move poleward and diversify harvests ( ''medium evidence, high agreement'' ) (Sections 3.4.3.3.3, 5.8.4; Table 3.26; [[#Leitão--2018|Leitão et al., 2018]] ; [[#Liang--2018|Liang et al., 2018]] ; [[#Ottosen--2018|Ottosen et al., 2018]] ; [[#Peck--2018|Peck and Pinnegar, 2018]] ; [[#Pinsky--2018|Pinsky et al., 2018]] ; [[#Erauskin-Extramiana--2019|Erauskin-Extramiana et al., 2019]] ; [[#Free--2019|Free et al., 2019]] ; [[#Gianelli--2019|Gianelli et al., 2019]] ; [[#Scott--2019|Scott et al., 2019]] ; [[#Smith--2019|Smith et al., 2019]] ; [[#Gervais--2021|Gervais et al., 2021]] ). Model hindcasts have identified temperature-associated fisheries reductions worldwide ( [[#Free--2019|Free et al., 2019]] ), and they have implicated overfishing as the primary non-climate driver increasing fishery vulnerability ( [[IPCC:Wg2:Chapter:Chapter-5#5.8.4|Section 5.8.4]] ; [[#Peck--2018|Peck and Pinnegar, 2018]] ; [[#Das--2020|Das et al., 2020]] ). Catch composition is changing in many locations fished by smaller-scale, less-mobile commercial, artisanal and recreational fisheries ( ''high confidence'' ) ( [[#Booth--2018|Booth et al., 2018]] ; [[#Townhill--2019|Townhill et al., 2019]] ; [[#Young--2019b|Young et al., 2019b]] ; [[#Robinson--2020|Robinson et al., 2020]] ; [[#Champion--2021|Champion et al., 2021]] ). Limited exceptions have been noted, with wild harvests in some places remaining stable or increasing (e.g., [[#Arreguín-Sánchez--2019|Arreguín-Sánchez, 2019]] ; [[#Robinson--2019b|Robinson et al., 2019b]] ; [[#Kainge--2020|Kainge et al., 2020]] ). Where possible, fishers are maintaining harvests by broadening catch diversity, traveling poleward and changing gear and strategies ( ''high confidence'' ) ( [[#3.6.3.1.2|Section 3.6.3.1.2]] ; [[#Barange--2018|Barange et al., 2018]] ; [[#Dubik--2019|Dubik et al., 2019]] ; [[#Townhill--2019|Townhill et al., 2019]] ). Fisheries and aquaculture adaptations, including management, are comprehensively assessed in Sections 3.6.3.1.2, 5.8.4 and 5.9.4.

Ocean acidification and deoxygenation caused by climate change are thought to influence fishing and aquaculture harvests, but ''limited evidence'' prevents assessing their present global impact on harvests. Substantial economic losses in the North American Pacific Coast shellfish aquaculture industry in the 2000s assessed in SROCC ( [[#Bindoff--2019a|Bindoff et al., 2019a]] ) and WGII AR5 ( [[#Pörtner--2014|Pörtner et al., 2014]] ) remain the clearest example of human harm from ocean acidification. Technology-based adaptations ( [[#3.6.3|Section 3.6.3]] ) have minimised aquaculture losses from ocean acidification, including early-warning systems to guide hatchery operations and culturing resilient shellfish strains ( [[IPCC:Wg2:Chapter:Chapter-5#5.9.4|Section 5.9.4]] ; [[#Barton--2015a|Barton et al., 2015a]] ). Laboratory studies show that ocean acidification decreases the fitness, growth or survival of many economically and culturally important larval or juvenile shelled mollusks ( ''high confidence'' ) ( [[#Cao--2018|Cao et al., 2018]] ; [[#Onitsuka--2018|Onitsuka et al., 2018]] ; [[#Stevens--2018|Stevens and Gobler, 2018]] ; [[#Griffith--2019a|Griffith et al., 2019a]] ; [[#Mellado--2019|Mellado et al., 2019]] ) and of several valuable wild-harvest crab species ( [[#Barton--2015a|Barton et al., 2015a]] ; [[#Punt--2015|Punt et al., 2015]] ; [[#Miller--2016|Miller et al., 2016]] ; [[#Swiney--2017|Swiney et al., 2017]] ; [[#Gravinese--2018|Gravinese et al., 2018]] ; [[#Tomasetti--2018|Tomasetti et al., 2018]] ; [[#Long--2019|Long et al., 2019]] ; [[#Trigg--2019|Trigg et al., 2019]] ). Ocean acidification alters larval settlement and metamorphosis of fish in laboratory studies ( ''high confidence'' ) ( [[#Cattano--2018|Cattano et al., 2018]] ; [[#Espinel-Velasco--2018|Espinel-Velasco et al., 2018]] ), suggesting possible changes in fish survival and thus fishery characteristics. Deoxygenation can decrease size and abundance of marine species and suppress trophic interactions ( [[#Levin--2003|Levin, 2003]] ), decrease the diversity within marine ecosystems ( [[#Sperling--2016|Sperling et al., 2016]] ) while temporarily increasing catchability and increasing the risk of overfishing ( [[#Breitburg--2018|Breitburg et al., 2018]] ) and decrease the ecosystem services provided by specific fisheries ( [[#Orio--2021|Orio et al., 2021]] ). The chronic effects of deoxygenation on wild fisheries are complex and highly interactive with co-occurring drivers and overall ecosystem responses ( ''medium evidence, high agreement'' ) ( [[#Townhill--2017|Townhill et al., 2017]] ; [[#Rose--2019|Rose et al., 2019]] ). Detecting and attributing marine ecosystem responses to ocean acidification and deoxygenation outside of laboratory studies remains challenging because of the strong influence of co-occurring environmental changes on natural systems ( [[#3.3.5|Section 3.3.5]] ; [[#Rose--2019|Rose et al., 2019]] ; [[#Doo--2020|Doo et al., 2020]] ).

Ocean and coastal organisms will continue moving poleward under RCP8.5 ( ''high confidence'' ) ( [[#3.4.3.1.3|Section 3.4.3.1.3]] ; Figure 3.18), and this is expected to decrease fisheries harvests in low latitudes and alter species composition and abundance in higher latitudes ( ''high confidence'' ) (Table 3.26; Figure 3.23; [[#Asch--2018|Asch et al., 2018]] ; [[#Morley--2018|Morley et al., 2018]] ; [[#Tai--2019|Tai et al., 2019]] ; [[#Erauskin-Extramiana--2020|Erauskin-Extramiana et al., 2020]] ; [[#Shelton--2021|Shelton et al., 2021]] ). Species that succeed in new ranges or conditions may offer opportunities to diversify regional fisheries or aquaculture (Sections 3.6.3.1.2, 5.8.4, 5.9.4; [[#Bindoff--2019a|Bindoff et al., 2019a]] ), or they may outcompete indigenous species and act as invasive species (Sections 3.4.2.10, 3.5.2).

Temperature will continue to be a major driver of fisheries changes globally, but other non-climate factors like organism physiology and ecosystem response ( [[#3.3|Section 3.3]] ) and fishing pressure (Chapter 5), as well as other climate-induced drivers like acidification, deoxygenation and sea ice loss ( [[#3.2|Section 3.2]] ), will play critical roles in future global and local fisheries changes ( ''high confidence'' ). Warming, acidification and business-as-usual fishing policy under RCP8.5 are projected to place around 60% of global fisheries at very high risk ( ''medium confidence'' ) ( [[#Cheung--2018|Cheung et al., 2018]] ). Model intercomparison showed that ocean acidification and protection affect ecosystems more than fishing pressure, and ecological adaptation will significantly determine impacts on fishery biomass, catch and value until approximately 2050 ( ''medium confidence'' ) ( [[#Olsen--2018|Olsen et al., 2018]] ). Ecosystem responses to warming water, fishing pressure, food-web changes, MHWs and sea ice algal populations have been responsible for highly variable or collapsing populations of Northern Hemisphere high-latitude forage fish species including sand lances ( ''Ammodytes'' spp ''.'' ), Arctic cod ( ''Boreogadus saida'' ), capelin ( ''Mallotus catervarius'' ) and herring ( ''Clupea'' spp ''.'' ) ( [[#Lindegren--2018|Lindegren et al., 2018]] ; [[#Steiner--2019|Steiner et al., 2019]] ; [[#Arimitsu--2021|Arimitsu et al., 2021]] ; [[#Suca--2021|Suca et al., 2021]] ). Declining stocks of forage fish are expected to have detrimental effects on seabirds, pelagic fish and marine mammals ( ''medium confidence'' ) ( [[#Lindegren--2018|Lindegren et al., 2018]] ; [[#Steiner--2019|Steiner et al., 2019]] ), which may harm dependent human communities, including Arctic Indigenous Peoples ( ''low confidence'' ) ( [[#Arctic%20Monitoring%20and%20Assessment%20Programme--2018|Arctic Monitoring and Assessment Programme, 2018]] ; [[#Steiner--2019|Steiner et al., 2019]] ). Modelled fishery futures and revenue depend on environmental scenario, fishing-fleet composition and management, and ocean acidification and temperature responses of harvested species ( ''high confidence'' ) ( [[#Punt--2014|Punt et al., 2014]] ; [[#Punt--2015|Punt et al., 2015]] ; [[#Seung--2015|Seung et al., 2015]] ; [[#Fernandes--2017|Fernandes et al., 2017]] ; [[#Rheuban--2018|Rheuban et al., 2018]] ; [[#Tai--2019|Tai et al., 2019]] ; [[#Punt--2020|Punt et al., 2020]] ). Detrimental effects of ocean acidification are projected to begin emerging in specific fisheries by 2030 ( ''limited evidence, high agreement'' ) [(southern Tanner crab ( ''Chionoecetes bairdi'' ) ( [[#Punt--2015|Punt et al., 2015]] ); sea scallop ( ''Placopecten magellanicus'' ) ( [[#Rheuban--2018|Rheuban et al., 2018]] ); Northeast Arctic cod ( ''Gadus morhua'' ) ( [[#Hänsel--2020|Hänsel et al., 2020]] ); Arctic fisheries ( [[#Lam--2016|Lam et al., 2016]] )]. At the same time, projected hypoxic conditions of ~2 mg l –1 of oxygen will be consistently detrimental across taxonomic groups, developmental stages and climate regions ( ''high confidence'' ) ( [[#Sampaio--2021|Sampaio et al., 2021]] ). Ecosystem-based management ( [[#3.6.3.1.2|Section 3.6.3.1.2]] ) shows promise for decreasing risk from interacting climate and non-climate drivers to forage species and fished species.

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