Aquaculture Climate Change Direct

In Bangladesh, the world’s fifth-largest aquaculture producer, sea-level rise threatens 50% of the coastal shrimp and prawn farms. Saltwater intrusion also contaminates freshwater aquifers used for hatcheries and processing. Farmers face a cruel irony: shrimp farming requires brackish water, but the precise salinity tolerance of black tiger shrimp (15-25 ppt) is narrow; too much freshwater from upstream dams, or too much salt from sea intrusion, both cause mortality. Climate change intensifies the hydrologic cycle, producing more frequent and severe cyclones, floods, and droughts. For aquaculture, which requires stable water quality and physical infrastructure, extreme weather is an immediate, destructive hammer.

In Norway and Scotland, Atlantic salmon farmers have experienced catastrophic mortality events during marine heatwaves. The 2019 event in Norway killed 10 million salmon—roughly 15% of the annual harvest—as temperatures exceeded 22°C, the species’ upper tolerance. Salmon cease feeding above 20°C, become immunocompromised, and succumb to sea lice and bacterial diseases. In warmer waters, metabolic rates accelerate, increasing oxygen demand while simultaneously reducing dissolved oxygen solubility. The result is a physiological vise: fish need more oxygen but have less available. aquaculture climate change

Climate-smart certification is urgently needed: standards requiring renewable energy for RAS, mangrove conservation for tropical shrimp, and lifecycle emissions disclosure for all fed species. The Global Seafood Alliance’s new “Climate Certified” pilot program, launched in 2023, represents a first step—but voluntary certification covers only 15% of global production. Government subsidies drive aquaculture expansion, and they are overwhelmingly misaligned with climate goals. The OECD estimates that global fisheries and aquaculture subsidies total $35 billion annually, with $22 billion classified as “harmful” (fuel subsidies for fishing vessels, infrastructure loans for mangrove-converting shrimp farms). Redirecting even 10% of harmful subsidies toward climate adaptation—offshore cage construction, RAS energy retrofits, mangrove restoration—would transform industry incentives. The 2019 event in Norway killed 10 million

Perhaps most alarming are the emerging viral diseases. Tilapia Lake Virus (TiLV), first identified in 2014, has now spread to five continents, with mortality rates exceeding 90% in some outbreaks. Climate models project that suitable temperature ranges for TiLV (22-32°C) will expand by 40% by 2050, exposing 70% of global tilapia farms. Farmers respond with antibiotics—75% of which pass through fish into surrounding waters, selecting for resistant bacteria that then infect wild populations and humans. Faced with this multi-front assault, the aquaculture industry is not passive. Farmers, scientists, and engineers are developing an arsenal of adaptation strategies, ranging from low-tech traditional knowledge to high-tech genetic engineering. Location, Location, Location: Moving Offshore and Onshore The most fundamental adaptation is geographical. As coastal waters become untenable, two divergent paths emerge: moving further offshore into deeper, more thermally stable waters, or moving entirely onshore into recirculating systems. Unlike wild fisheries

Yet there is reason for cautious optimism. Unlike wild fisheries, which can only retreat before changing oceans, aquaculture can adapt, innovate, and transform. The emerging blueprint for climate-resilient aquaculture is visible in pilot projects and research stations worldwide: offshore submersible cages powered by floating wind turbines, land-based RAS facilities heated by waste industrial heat, mangrove-shrimp polycultures generating carbon credits, seaweed farms sequestering megatons of CO2 while producing biofuel feedstocks.