Climate Change & Fisheries PDF

Climate change & fisheries Dirk Zeller Sea Around Us – Indian Ocean Climate change Facts are established… Is happening much faster than generally projected Is caused/driven by human industrial action Impacts/outcomes much worse than most models/reports suggest – Cf...

Climate change & fisheries Dirk Zeller Sea Around Us – Indian Ocean Climate change Facts are established… Is happening much faster than generally projected Is caused/driven by human industrial action Impacts/outcomes much worse than most models/reports suggest – Cf. Scientific caution…… Good to very good understanding of impacts and outcomes, but not complete …  2015 Paris Agreement: Keep well below 2o C and aim for 1.5o C Currently on path to 3-4o C What will a 4o C earth be like? President of the World Bank Group in 2012: “The explored consequences of an increase of the global earth temperature of 4o C are devastating” Among the foreseen consequences are: Inundation of coastal cities; Increasing risks to food production; Higher malnutrition rates; Dry regions becoming dryer and wet regions wetter; Unprecedented heat waves in many regions, especially in the tropics; Substantially exacerbated water scarcity in many regions; Increased frequency and unpredictability of high-intensity storms; Increased fires and fire intensity; Irreversible loss of biodiversity, including coral reef systems. Sounds familiar already? World Bank (2012) Turn down the heat: Why a 4o C warmer world must be avoided. A Report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics, Washington. xix & 84 p.  Australian 2019-2020 fires - ~ 18.6 million hectares USA fires - > 90 fires, ~ 1.2 million hectares Mediterranean fires – ~ 300,000 hectares Canadian fires – ~ 7,300 fires, ~ 2.5 million hectares Alaskan fires - ~ 400,000 hectares Siberian fires – ~ 17.1 million hectares – Siberia forest blazes were bigger than all the other wildfires burning in the world combined – The size of two Portugal or three Tasmania Arctic fires & warming: Thawing the permafrost … potential to release the world’s largest deposits of methane (25x worse than CO2)… positive feedback loop – Thermokarst depression – a kind of sinkhole or 'mega-slump' driven by the collapse and fracturing of land due to permafrost loss. – “Gateway to Hell” 5/34  Currently ~1 km across, 50-100 m deep Growing by 35 million cubic feet per year (>900 million litres per year) Growth is speeding up https://youtu.be/PmvWVDkyDAo Un-extractable fossil fuels in a 1.5o C world (8 September 2021) Assess the amount of fossil fuels that would need to be left in the ground to allow for a 50% probability of limiting warming to 1.5o C Nearly 60% of oil and fossil methane gas, and 90% of coal must remain un- extracted Oil and gas production must decline globally by 3% each year until 2050 Implies that most regions must reach peak production now, rendering many operational and planned fossil fuel projects unviable Present an underestimate of the production changes required, because a greater than 50% probability of limiting warming to 1.5o C requires even more carbon to stay in the ground Welsby et al. (2021) Nature 597(7875): 230-234 Example of poor colour choices for map…. Green = bad? Better: green, yellow, orange to red Welsby et al. (2021) Nature 597(7875): 230-234  Impacts of climate change on oceans Increase in average water temperature Change in oxygen content Acidification Sea level rise Changes in ocean current regimes Changes in weather patterns and frequencies (cyclones, rainfall, etc.) Implications for marine life https://blog.csiro.au/warming-oceans-are-changing-australias-fishing-industry/  Changes in ocean temperature Sea surface temperature Not all areas heating up Some cooling down But: Most coastal warming Some pelagic cooling 10/34 Cheung et al. (2013) Nature 497: 365-368 Changes in ocean temperature Impact on biodiversity and species richness Changes by 2050 modelled at ½ degree cell resolution Numerous local extinctions in the tropics and semi-enclosed seas Species invasions to be most intense in the Arctic and the Southern Ocean Overall, dramatic species turnover of > 60% of the present biodiversity Cheung et al. (2009) Fish & Fisheries 10(3): 235-251 Changes in ocean temperature Western Australia - shift in species distribution Latitudinal shift Shift in depth Latitudinal shift: 19 km/decade towards higher latitudes Depth shift: 9 m/decade towards deeper waters ‘Tropicalization’ of Western Australia coast Species gains (south) and losses (north) along the coast of WA Changes in fisheries dynamics Cheung et al. (2009) Fish & Fisheries 10(3): 235-251  Changes in ocean temperature Impact on fisheries: catch potential (no other factors but temp.) Change in max. catch potential from 2005 to 2050 Large-scale redistribution of global catch potential High-latitudes: potential increase of 30–70% Tropics: drop of up to 40% Cheung et al. (2010) Global Change Biology 16(1): 24-35 Changes in ocean temperature Impact on fisheries: catch potential Top 20 countries Cheung et al. (2010) Global Change Biology 16(1): 24-35 Changes in ocean temperature Another way of looking at it 15/34 Cheung et al. (2010) Global Change Biology 16(1): 24-35 Changes in ocean temperature Recent work: Poleward shifts in commercial fishing vessel distribution In Bering Sea 2013-2022 (VMS data) Vlietstra & Thoenen (2024) Polar Biology 47: 1121–1135 Changes in ocean temperature Recent work: Poleward shifts in commercial fishing vessel distribution In Bering Sea 2013-2022 (VMS data) Vlietstra & Thoenen (2024) Polar Biology 47: 1121–1135 Changes in ocean temperature Recent work: Poleward shifts in commercial fishing vessel distribution In Bering Sea 2013-2022 (VMS data) Why most strongly in wintertime? (yes: Oct-Feb is wintertime in Alaska ) Vlietstra & Thoenen (2024) Polar Biology 47: 1121–1135  Changes in oxygen content Physics 101 Warmer water holds less oxygen than colder water Cheung et al. (2013) Nature Climate Change 3: 254-258  Changes in oxygen content Biology 101 Water breathing animals are oxygen constrained - Water has lower O2 concentration than air - Water has much higher viscosity than air - Try breathing only through a straw for an hour…. Everything water breathing animals do is limited by ability to obtain O2 - Growth, reproduction, feeding, activity patterns, behaviour etc. - More big fish spp. in temperate areas than tropics Thus, the warmer the water, the less O2 … the smaller the fish Body weight of fish within a species expected to shrink by 14-24% globally Tropical and semi-tropical areas most heavily affected (>20%) Cheung et al. (2013) Nature Climate Change 3: 254-258 Acidification (lower pH) Oceans to become 150% more acidic by the end of century Harmful to oysters, corals, plankton and shellfish that grow hard shells made of calcium carbonate (CaCO3). Higher acidity (lower pH) dissolves those shells, or reduces shell formation Zooplankton are a fundamental link in food webs, yet heavily dependent on CaCO3 Lower pH affects the development of otoliths (ear bones) critical for fish balance, sensory perception and smell Impacts throughout the food web Acidification (lower pH) US Alaska red king crab US Pacific coast clams & scallops Survival rate of crab embryos which Malformed and eroded shells subsequently recruit to the first stage Punt et al. (2014) Ecological Modelling 285: 39-53 Freely et al. (eds) (2012) Scientific Summary of Ocean Acidification in Washington State Marine Waters. 20/34 NOAA/Pacific Marine Environmental Laboratory. Contribution no. 3934. Sea level rise Thermal expansion of ocean water mass Melting of polar ices sheets Sea level rise Sea level predictions: Globally risen by 20+ cm since 1880 Rate of sealevel rise has doubled from 1.4 mm/yr to 3.5 mm/yr By 2100 (your lifetime… your children): Conservatively (guaranteed): 1-2 m Potentially (likely, West Antarctic ice shelf melt): 3-15 m Add in storm surges….. See current impact of cyclones in Florida  Sea level rise The way we usually think...  Sea level rise The way we NEED to think of this. Not a small island problem only…  Sea level rise UWA with 1 m sea level rise… 25/34  Sea level rise UWA with 3 m sea level rise…  Sea level rise UWA with 5 m sea level rise… Sea level rise So, what about fisheries? Inundated coastal areas More new fish habitat? More shallow water fishing areas? Impact on coral reefs and coastal mangroves Current shelf waters will be deeper Reefs will be deeper Speed of sea level rise vs. vertical growth rates Potential consequences Reduced coastal storm surge protection Reduced coral reefs and mangrove fish habitat (fish nurseries) Changes in currents Gulf stream has slowed down by 20% over last few decades Larval export Transoceanic migrations 30/34 Weather and climate in Europe Changes in currents Gulf stream is main driver of the global conveyer belt of ocean circulation….. Guaranteed to have massive impacts we cannot even begin to predict  Changes in weather patterns Stronger and more frequent storm and extreme events Impact on coastal systems and coral reefs Habitats of commercially important species  Conclusion I don’t often take a strong activist stand…. But Our societal-political inaction on the climate emergency is negatively impacting everything we do and value, and damaging your future Change/leadership actions needed urgently, and faster and stronger than all politicians claim Politicians never lead, they always follow overwhelming perceived voter sentiments (even if miss- or ill-informed) and lobby group interests….. ‒ You have to lead…. Cost of continued inaction far exceeds the cost of change claimed by industry Australia could be the ”lucky country” again… but only if we get out of “carbon mining” (fossil fuel) now and turn Australia into the renewable energy powerhouse of Asia… ‒ No other place better suited… politically stable, essentially unlimited renewable power resources (solar/wind), low population density, well educated, sufficient space ‒ Solar & wind farms, smart home/communal/large grid batteries, smart transmission grid ‒ Green hydrogen – ammonia conversion… foundation for export industry How fund? Redirect fossil fuel industry subsidies (oil, gas, coal) to renewable and smart grid development and e-transport…. ‒ 2023-24: $14.5 billion, increase of 31% on the $11.1 billion recorded in 2022–23 ‒ $27,581 for every minute of every day, or $540 for every person in Australia Climate change reading https://www.bbc.com/future/article/20230607-as-ocean-oxygen-levels-dip-fish-face-an-uncertain-future Sumaila UR, de Fontaubert C and Palomares MLD (2023) Editorial: How overfishing handicaps resilience of marine resources under climate change. Frontiers in Marine Science 10. https://doi.org/10.3389/fmars.2023.1250449 Hodapp D, Roca IT, Fiorentino D, Garilao C, Kaschner K, Kesner-Reyes K, Schneider B, Segschneider J, Kocsis ÁT, Kiessling W, Brey T and Froese R (2023) Climate change disrupts core habitats of marine species. Global Change Biology 29(12): 3304-3317. https://doi.org/10.1111/gcb.16612 Andersen NF, Cavan EL, Cheung WWL, Martin AH, Saba GK and Sumaila UR (2024) Good fisheries management is good carbon management. npj Ocean Sustainability 3(1): 17. https://doi.org/10.1038/s44183-024-00053-x Santana-Falcón Y, Yamamoto A, Lenton A, Jones CD, Burger FA, John JG, Tjiputra J, Schwinger J, Kawamiya M, Frölicher TL, Ziehn T and Séférian R (2023) Irreversible loss in marine ecosystem habitability after a temperature overshoot. Communications Earth & Environment 4(1): 343. https://doi.org/10.1038/s43247-023-01002-1 https://theconversation.com/even-temporary-global-warming-above-2-will-affect-life-in-the-oceans-for-centuries-214251 Breitburg D, Levin LA, Oschlies A, Grégoire M, Chavez FP, Conley DJ, Garçon V, Gilbert D, Gutiérrez D, Isensee K, Jacinto GS, Limburg KE, Montes I, Naqvi SWA, Pitcher GC, Rabalais NN, Roman MR, Rose KA, Seibel BA, Telszewski M, Yasuhara M and Zhang J (2018) Declining oxygen in the global ocean and coastal waters. Science 359(6371): eaam7240. DOI: 10.1126/science.aam7240 Sea Around Us – Indian Ocean