Editing IPCC:AR6/WGII/Chapter-5 (section)

==== 5.9.3.2 Marine Aquaculture ====

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===== 5.9.3.2.1 Finfish culture =====

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Global projections of ocean warming, primary productivity and ocean acidification predict suitable habitat expansions and short-term growth benefits for finfish aquaculture for some regions ( ''medium confidence'' ) (see Figure 5.15) until thermal tolerances or productivity constraints are exceeded by 2090 ( [[#Beveridge--2018b|Beveridge et al., 2018b]] ; [[#Dabbadie--2018|Dabbadie et al., 2018]] ; [[#Froehlich--2018a|Froehlich et al., 2018a]] ; [[#Catalán--2019|Catalán et al., 2019]] ; [[#Thiault--2019|Thiault et al., 2019]] ; [[#Falconer--2020a|Falconer et al., 2020a]] ). Sensitivities for marine finfish may be high even under +1.5–2.0°C ( ''medium confidence'' ) ( [[#Gattuso--2018|Gattuso et al., 2018]] ), resulting in finfish farms moving northward to maintain productivity (e.g., Arctic ( [[#Troell--2017|Troell et al., 2017]] )). Downscaled projections of regionally specific tolerances ( [[#Klinger--2017|Klinger et al., 2017]] ) may be particularly useful for management and planning; a 0.5°C rise is predicted for Chilean salmon aquaculture ( [[#Soto--2019|Soto et al., 2019]] ), and potential negative impacts on productivity in Norway by 2029 have been projected ( ''limited evidence'' ) ( [[#Falconer--2020a|Falconer et al., 2020a]] ). Marine heatwaves are predicted to increase in occurrence, intensity and persistence under RCP4.5 or RCP8.5 by 2100 ( [[#Oliver--2019|Oliver et al., 2019]] ; [[#Bricknell--2021|Bricknell et al., 2021]] ), with risk partly mitigated by husbandry ( ''medium confidence'' ) ( [[#McCoy--2017|McCoy et al., 2017]] ). Generally, negative impacts are predicted for marine species, with residual risk increasing with level of exposure ( [[#Sara--2018|Sara et al., 2018]] ; [[#Smale--2019|Smale et al., 2019]] ), where warming will affect oxygen solubility and reduce salmon culture capacity ( ''limited evidence'' ) ( [[#Aksnes--2019|Aksnes et al., 2019]] , Chapter 3) and combine with increasing incidence of HABs ( ''high confidence'' ) resulting in negative impacts for food security and nutrition and health ( [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ; [[#Colombo--2020|Colombo et al., 2020]] ; [[#Glibert--2020|Glibert, 2020]] ; [[#Raven--2020|Raven et al., 2020]] ). Climate change is predicted to affect the incidence, magnitude and virulence of finfish disease such as ''Vibriosis'' ( [[#Barber--2016|Barber et al., 2016]] ; [[#Mohamad--2019a|Mohamad et al., 2019a]] ; [[#Mohamad--2019b|Mohamad et al., 2019b]] ), but specific host–pathogen–climate relationships are not yet established ( ''high confidence'' ) ( [[#Slenning--2010|Slenning, 2010]] ; [[#Marcogliese--2016|Marcogliese, 2016]] ; [[#Montanchez--2019|Montanchez et al., 2019]] ; [[#Bandin--2020|Bandin and Souto, 2020]] ; [[#Behringer--2020|Behringer et al., 2020]] ; [[#Filipe--2020|Filipe et al., 2020]] ; [[#Montanchez--2020|Montanchez and Kaberdin, 2020]] ). Projected climate change will also increase competition for feed ingredients between aquatic and terrestrial animal production systems (see [[#5.13.2|Section 5.13.2]] .).

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===== 5.9.3.2.2 Shellfish culture =====

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Globally, there is overall ''high confidence'' that suitable shellfish aquaculture habitat will decline by 2100 under projected warming, ocean acidification and primary productivity changes, with significant negative impacts for some regions and species before 2100 (Table 5.9, [[#Froehlich--2018a|Froehlich et al., 2018a]] ; [[#Ghezzo--2018|Ghezzo et al., 2018]] ). Shellfish growth will increase with warming waters until tolerances are reached, such as through extreme El Niño events ( ''high confidence'' ) ( [[#Beveridge--2018b|Beveridge et al., 2018b]] ; [[#Dabbadie--2018|Dabbadie et al., 2018]] ; [[#Liu--2018b|Liu et al., 2018b]] ; [[#Liu--2020|Liu et al., 2020]] ). Rising temperatures and ocean acidification will result in losses of primary productivity and farmed species from tropical and subtropical regions, and gains in higher latitudes ( ''high confidence'' ) ( [[#Froehlich--2018a|Froehlich et al., 2018a]] ; [[#Aveytua-Alcazar--2020|Aveytua-Alcazar et al., 2020]] ; [[#Chapman--2020|Chapman et al., 2020]] ; [[#Des--2020|Des et al., 2020]] ; [[#Oyinlola--2020|Oyinlola et al., 2020]] ), but net marine production gains could be achieved under strong mitigation ( [[#Thiault--2019|Thiault et al., 2019]] ). Shellfish ''Vibrio'' infections will increase with warming waters and extreme events, increasing shellfish mortalities ( ''medium confidence'' ) ( [[#Green--2019|Green et al., 2019]] ; [[#Montanchez--2019|Montanchez et al., 2019]] ), with ocean acidification impairing immune responses ( ''limited evidence'' ) ( [[#Cao--2018b|Cao et al., 2018b]] ). Bivalve larvae are known to be highly vulnerable to ocean acidification ( ''high confidence'' ) (see [[IPCC:Wg2:Chapter:Chapter-3#3.3|Section 3.3]] , [[#Bindoff--2019|Bindoff et al., 2019]] ), with projected regional and species-specific levels of impact ( ''high confidence'' ) ( [[#Ekstrom--2015|Ekstrom et al., 2015]] ; [[#Zhang--2017b|Zhang et al., 2017b]] ; [[#Mangi--2018|Mangi et al., 2018]] ) ( [[#Greenhill--2020|Greenhill et al., 2020]] ). Ocean acidification is also projected to weaken shells, affecting productivity and processing ( ''high confidence'' ) ( [[#Martinez--2018|Martinez et al., 2018]] ; [[#Cummings--2019|Cummings et al., 2019]] ) and dependent livelihoods ( [[#Doney--2020|Doney et al., 2020]] ).

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===== 5.9.3.2.3 Aquatic plant culture =====

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There is ''medium confidence'' that cultivated seaweeds are predicted to suffer habitat loss resulting in population declines and northward shifts (Table 5.11).

'''Table 5.11 |''' Projected impacts of climate on specific inland, brackish and marine culture systems and species.

{| class="wikitable"
|-
! '''Exposure'''

! '''Scenario'''

! '''Region'''

! '''Production system'''

! '''Species'''

! '''Impact'''

! '''Reference'''

|-
| Temperature increase

| RCP4.5 and RCP8.5 by 2050

| Northern Thailand

| Inland

| Nile tilapia

| Reduced productivity

| [[#Lebel--2018|Lebel et al. (2018)]]

|-
| Precipitation change (drought, hurricane, heavy rainfall)

| –

| Jamaica

| Inland

| Tilapia

| Reduced productivity, infrastructure damage

| Canevari-Luzardo et al. (2019)

|-
| Temperature increase

| 4°C increase, B2, A1B by 2100

| Australia

| Inland

| Freshwater shrimp

| Increased production in non-native zones

| [[#Cerato--2019|Cerato et al. (2019)]]

|-
| Temperature increase, ocean acidification, primary productivity declines

| CMIP5 RCP8.5 in 20-year increments to 2090

| Global

| Marine

| Finfish species

| Increased suitable habitat expansion for regions (Russia, Norway, USA Alaska, Denmark, Canada). By 2100, reduction in productivity for major producers (Norway, China)

| Froehlich et al. (2018a),

[[#Thiault--2019|Thiault et al. (2019)]]

|-
| Temperature increase

| 2–5°C increase under RCP8.5

| Europe

| Marine

| Atlantic salmon

| Increased growth

| [[#Catalán--2019|Catalán et al. (2019)]]

|-
| Temperature increase

| RCP4.5 to 2029

| Norway

| Marine

| Atlantic salmon

| Growth threshold reached by 2029

| [[#Falconer--2020a|Falconer et al. (2020a)]]

|-
| Temperature increase

| Downscaled CM2.6 by 2050

| Global

| Marine

| Atlantic salmon, cobia and sea bream

| Increased or decreased growth rates depending on region

| Klinger et al. (2017)

|-
| Temperature increase, ocean acidification, primary productivity declines

| CMIP5 RCP8.5 in 20-year increments to 2090

| Global

| Marine

| Shellfish

| Overall declines in suitable habitat globally, up to 50–100% reductions in regions in China, Thailand and Canada

| Froehlich et al. (2018a)

|-
| Temperature increase

| CMIP5 RCP8.5 by 2050, 2100

| Italy

| Marine

| Clams

| Negative impacts for juvenile timing, spatial distribution, and quality

| [[#Ghezzo--2018|Ghezzo et al. (2018)]]

|-
| Temperature increase

| CMIP5 RCP2.6 and RCP8.5 by 2035, 2070

| France

| Marine

| Oysters

| Increase incidence of oyster mortality; increase by 2035 to annual occurrence by 2070

| [[#Thomas--2018|Thomas et al. (2018)]]

|-
| Temperature increase

| RCP2.6 and RCP8.5 by 2050

| Global

| Marine

| Shellfish

| Species reduction (10–40%) in tropical and subtropical regions, with increase (40%) in higher latitudes

| [[#Oyinlola--2020|Oyinlola et al. (2020)]]

|-
| Temperature increase, ocean acidification

| Ecopath with RCP8.5 by 2100 (2.8°C warming and pH 7.89)

| USA

| Marine

| Shellfish

| Reduction primary productivity and subsequent bivalve carrying capacity

| [[#Chapman--2020|Chapman et al. (2020)]]

|-
| Temperature increase, stratification change

| RCP8.5 by 2088–2099

| Spain

| Marine

| Mussels

| Decline in mussel optimal culture conditions of 60% in upper and 30% in deeper waters by 2099

| [[#Des--2020|Des et al. (2020)]]

|-
| Temperature increase, ocean acidification

| RCP2.6 and 8.5 by 2070–2090

| Global

| Marine

| Shellfish

| Under RCP8.5, a decline in shellfish production due to primary productivity reduction in tropical regions and gains in high latitudes. Under RCP2.6, marine production will have net gain

| [[#Thiault--2019|Thiault et al. (2019)]]

|-
| Temperature increase

| 4°C increase

| Global

| Marine

| ''Vibrio'' spp. (mortality causative agent)

| Increased virulence

| [[#Montanchez--2019|Montanchez et al. (2019)]]

|-
| Temperature increase (marine heatwave)

| 5°C increase

| Global

| Marine

| Oysters

| Increased oyster mortality

| [[#Green--2019|Green et al. (2019)]]

|-
| Ocean acidification

| ~2000 ppm CO 2

| Global

| Marine

| Oysters

| Impaired immune function

| [[#Cao--2018b|Cao et al. (2018b)]]

|-
| Ocean acidification

| RCP8.5 in 20-year increments to after 2099

| USA

| Marine

| Shellfish

| Regional projected vulnerabilities; southern Alaska and Pacific Northwest at more immediate risk

| [[#Ekstrom--2015|Ekstrom et al. (2015)]]

|-
| Ocean acidification

| A1B and RCP8.5 by 2100

| UK

| Marine

| Shellfish

| Regional projected vulnerabilities; Wales and England at more immediate risk

| [[#Mangi--2018|Mangi et al. (2018)]]

|-
| Ocean acidification

| RCP2.6 and RCP8.5 by 2300

| East China

| Marine

| Shellfish

| Carbonate saturation projected to decrease by 13% and 72% under RCP2.6 and RCP8.5 respectively, projecting decreased shellfish productivity

| RCP2.6 and RCP8.5 by 2300 ( [[#Zhang--2017b|Zhang et al., 2017b]] )

|-
| Increased temperature

| RCP2.6 and RCP8.5 by 2100

| North Sea

| Marine

| Seaweed

| Northward population shift by 110–163 km and 450–635 km under RCP2.6 and RCP8.5, respectively

| [[#Westmeijer--2019|Westmeijer et al. (2019)]]

|-
| Increased temperature

| RCP4.5 and RCP8.5 by 2090

| Japan

| Marine

| Kelp

| Habitat decline to 30–51% and 0–25% under RCP4.5 and RCP8.5, respectively

| [[#Sudo--2020|Sudo et al. (2020)]]

|}

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===== 5.9.3.2.4 Societal impacts within the production system =====

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Marine aquaculture provides distinct ecosystem services through provisioning (augmenting wild fishery catches), regulating (coastal protection, carbon sequestration, nutrient removal, improved water clarity), habitat and supporting (artificial habitat) and cultural (livelihoods and tourism) services ( [[#Gentry--2020|Gentry et al., 2020]] ), which vary with species, location and husbandry ( [[#Alleway--2019|Alleway et al., 2019]] ). Projected thermal increases of 1.5°C will reduce ecosystem services, further reduced under 2°C warming, with associated increases in acidification, hypoxia, dead zones, flooding and water restrictions ( ''medium confidence'' ) ( [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ). Sudden production losses from extreme climate events can exacerbate food security challenges across production sectors, including aquaculture, increasing global hunger ( ''high confidence'' ) ( [[#Cottrell--2019|Cottrell et al., 2019]] ; [[#Food%20Security%20Information%20Network--2020|Food Security Information Network, 2020]] ). While aquaculture provides positive influences such as food security and livelihoods, there are negative concerns over environmental impacts (including high nutrient loads from sites) and socioeconomic conflicts ( [[#Alleway--2019|Alleway et al., 2019]] ; [[#Soto--2019|Soto et al., 2019]] ), and adoption of ecosystem approaches is dependent on particular user groups and regions ( [[#Gentry--2017|Gentry et al., 2017]] ; [[#Brugère--2019|Brugère et al., 2019]] ; [[#Gentry--2020|Gentry et al., 2020]] ). In coastal Bangladesh, projected saline inundation to wetland ecosystem services will result in ecosystem services losses of raw materials and food provisioning, ranging from USD 0 to 20.0 million under RCP2.6 to RCP8.5 scenarios ( [[#Mehvar--2019|Mehvar et al., 2019]] ). Mangrove deforestation for shrimp farming in Asia negatively impacts ecosystem services and reduces climate resilience ( ''medium confidence'' ) ( [[#Mehvar--2019|Mehvar et al., 2019]] ; [[#Nguyen--2019|Nguyen and Parnell, 2019]] ; [[#Reid--2019|Reid et al., 2019]] ; [[#Custódio--2020|Custódio et al., 2020]] ), while mangrove reforestation efforts may have some effectiveness in re-creating important nursery grounds for aquatic species ( ''low confidence)'' ( [[#Gentry--2017|Gentry et al., 2017]] ; [[#Chiayarak--2019|Chiayarak et al., 2019]] ; [[#Hai--2020|Hai et al., 2020]] ). Families are highly vulnerable to climate change where nutritional needs are being met by self-production, such as in Mozambique, Namibia ( [[#Villasante--2015|Villasante et al., 2015]] ), Zambia ( [[#Kaminski--2018|Kaminski et al., 2018]] ) and Bangladesh ( ''high confidence'' ) ( [[#Pant--2014|Pant et al., 2014]] ). Climate change will therefore affect multiple ecosystem services where ultimately decisions on balance or trade-offs will vary with regional perceptions of service value ( ''high confidence'' ).

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