Editing IPCC:AR6/SR15/Chapter-3 (section)

==== 3.4.6.3 Fisheries and aquaculture production ====

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Global fisheries and aquaculture contribute a total of 88.6 and 59.8 million tonnes of fish and other products annually (FAO, 2016) <sup>[[#fn:r918|918]]</sup> , and play important roles in the food security of a large number of countries (McClanahan et al., 2015; Pauly and Charles, 2015) <sup>[[#fn:r919|919]]</sup> as well as being essential for meeting the protein demand of a growing global population (Cinner et al., 2012, 2016; FAO, 2016; Pendleton et al., 2016) <sup>[[#fn:r920|920]]</sup> . A steady increase in the risks associated with bivalve fisheries and aquaculture at mid-latitudes is coincident with increases in temperature, ocean acidification, introduced species, disease and other drivers (Lacoue-Labarthe et al., 2016; Clements and Chopin, 2017; Clements et al., 2017; Parker et al., 2017) <sup>[[#fn:r921|921]]</sup> . Sea level rise and storm intensification pose a risk to hatcheries and other infrastructure (Callaway et al., 2012; Weatherdon et al., 2016) <sup>[[#fn:r922|922]]</sup> , whilst others risks are associated with the invasion of parasites and pathogens (Asplund et al., 2014; Castillo et al., 2017) <sup>[[#fn:r923|923]]</sup> . Specific human strategies have reduced these risks, which are expected to be moderate under RCP2.6 and very high under RCP8.5 (Gattuso et al., 2015) <sup>[[#fn:r924|924]]</sup> . The risks related to climate change for fin fish (Section 3.4.4) are producing a number of challenges for small-scale fisheries (e.g., Kittinger, 2013; Pauly and Charles, 2015; Bell et al., 2018) <sup>[[#fn:r925|925]]</sup> . Recent literature from 2015 to 2017 has described growing threats from rapid shifts in the biogeography of key species (Poloczanska et al., 2013, 2016; Burrows et al., 2014; García Molinos et al., 2015) <sup>[[#fn:r926|926]]</sup> and the ongoing rapid degradation of key ecosystems such as coral reefs, seagrass and mangroves (Section 3.4.4, Box 3.4). The acceleration of these changes, coupled with non-climate stresses (e.g., pollution, overfishing and unsustainable coastal development), are driving many small-scale fisheries well below the sustainable harvesting levels required to maintain these resources as a source of food (McClanahan et al., 2009, 2015; Cheung et al., 2010; Pendleton et al., 2016) <sup>[[#fn:r927|927]]</sup> . As a result, future scenarios surrounding climate change and global population growth increasingly project shortages of fish protein for many regions, such as the Pacific Ocean (Bell et al., 2013, 2018) <sup>[[#fn:r928|928]]</sup> and Indian Ocean (McClanahan et al., 2015) <sup>[[#fn:r929|929]]</sup> . Mitigation of these risks involves marine spatial planning, fisheries repair, sustainable aquaculture, and the development of alternative livelihoods (Kittinger, 2013; McClanahan et al., 2015; Song and Chuenpagdee, 2015; Weatherdon et al., 2016) <sup>[[#fn:r930|930]]</sup> . Other threats concern the increasing incidence of alien species and diseases (Kittinger et al., 2013; Weatherdon et al., 2016) <sup>[[#fn:r931|931]]</sup> .

Risks of impacts related to climate change on low-latitude small-scale fin fisheries are moderate today but are expected to reach very high levels by 1.1°C of global warming. Projections for mid-to high-latitude fisheries include increases in fishery productivity in some cases (Cheung et al., 2013; Hollowed et al., 2013; Lam et al., 2014; FAO, 2016) <sup>[[#fn:r932|932]]</sup> . These projections are associated with the biogeographical shift of species towards higher latitudes (Fossheim et al., 2015) <sup>[[#fn:r933|933]]</sup> , which brings benefits as well as challenges (e.g., increased production yet a greater risk of disease and invasive species; ''low confidence'' ). Factors underpinning the expansion of fisheries production to high-latitude locations include warming, increased light levels and mixing due to retreating sea ice (Cheung et al., 2009) <sup>[[#fn:r934|934]]</sup> , which result in substantial increases in primary productivity and fish harvesting in the North Pacific and North Atlantic (Hollowed and Sundby, 2014) <sup>[[#fn:r935|935]]</sup> .

Present-day risks for mid-latitude bivalve fisheries and aquaculture become undetectible up to 1.1°C of global warming, moderate at 1.3°C, and moderate to high up to 1.9°C (Figure 3.18). For instance, Cheung et al. (2016a) <sup>[[#fn:r936|936]]</sup> , simulating the loss in fishery productivity at 1.5°C, 2°C and 3.5°C above the pre-industrial period, found that the potential global catch for marine fisheries will ''likely'' decrease by more than three million metric tonnes for each degree of warming. Low-latitude fin-fish fisheries have higher risks of impacts, with risks being moderate under present-day conditions and becoming high above 0.9°C and very high at 2°C of global warming. High-latitude fisheries are undergoing major transformations, and while production is increasing, present-day risk is moderate and is projected to remain moderate at 1.5°C and 2°C (Figure 3.18).

Adaptation measures can be applied to shellfish, large pelagic fish resources and biodiversity, and they include options such as protecting reproductive stages and brood stocks from periods of high ocean acidification (OA), stock selection for high tolerance to OA ( ''high confidence'' ) (Ekstrom et al., 2015; Rodrigues et al., 2015; Handisyde et al., 2016; Lee, 2016; Weatherdon et al., 2016; Clements and Chopin, 2017) <sup>[[#fn:r937|937]]</sup> , redistribution of highly migratory resources (e.g., Pacific tuna) ( ''high confidence'' ), governance instruments such as international fisheries agreements (Lehodey et al., 2015; Matear et al., 2015) <sup>[[#fn:r938|938]]</sup> , protection and regeneration of reef habitats, reduction of coral reef stresses, and development of alternative livelihoods (e.g., aquaculture; Bell et al., 2013, 2018) <sup>[[#fn:r939|939]]</sup> .

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