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Aquaculture: the story on HearLore | HearLore
Aquaculture
The Gunditjmara people of south-western Victoria, Australia, were raising short-finned eels as early as 4580 BCE, creating a complex system of channels and dams on volcanic floodplains near Lake Condah. This ancient aquaculture site, now known as the Budj Bim Cultural Landscape, stands as one of the oldest known examples of farming aquatic life in human history. While modern society often associates fish farming with industrial cages and high-tech feed, these Indigenous Australians developed a sophisticated method of trapping and preserving eels to ensure a food supply throughout the year. They utilized woven traps and managed water levels to control the eel population, demonstrating an understanding of aquatic ecosystems that predates written history by millennia. This early practice laid the groundwork for the concept of controlled cultivation, proving that the desire to manage food sources from water is as old as humanity itself.
The Blue Revolution Begins
In 1973, the renowned ocean explorer Jacques Cousteau declared that with Earth's burgeoning human populations to feed, humanity must turn to the sea with new understanding and technology. This call to action sparked the so-called Blue Revolution, a movement intended to replicate the agricultural success of the Green Revolution within the oceans. The goal was to domesticate marine species to meet the growing demand for high-quality protein, shifting the paradigm from harvesting wild fish to farming them. By the early 21st century, the industry had grown so rapidly that aquaculture production surpassed capture fisheries in 2014, marking a historic turning point in global food supply. The industry now accounts for nearly half of all fish consumed by humans, with global output reaching 130.9 million tonnes by 2022, valued at over 312 billion US dollars. This transformation was driven by the stagnation of wild fish stocks and the need to find alternative sources of protein, leading to the domestication of hundreds of species that were once exclusively caught from the wild.
The Salmon Paradox
The farming of salmon presents a complex contradiction known as the fish-in-fish-out ratio, where producing one kilogram of farmed salmon requires several kilograms of wild fish as feed. In 1995, this ratio stood at 7.5, meaning that for every pound of salmon harvested, 7.5 pounds of wild forage fish were consumed to produce it. Although the industry has improved efficiency, with the ratio dropping to 4.9 by 2006, the fundamental issue remains: carnivorous farmed fish still rely heavily on wild resources. This dependency creates a strain on forage fish populations like herring and sardines, which are essential for the survival of wild predator fish. The industry has responded by developing plant-based feeds and using residues from fish processing, yet the environmental cost of extracting wild fish for feed continues to be a major point of contention. Despite these challenges, salmon farming has become a major export industry, particularly in southern Chile, where it has driven the rapid growth of cities like Puerto Montt.
When did the Gunditjmara people start farming short-finned eels near Lake Condah?
The Gunditjmara people began raising short-finned eels as early as 4580 BCE. They created a complex system of channels and dams on volcanic floodplains near Lake Condah to manage the eel population and ensure a year-round food supply.
What year did aquaculture production surpass capture fisheries globally?
Aquaculture production surpassed capture fisheries in 2014. This historic turning point marked the shift where the industry now accounts for nearly half of all fish consumed by humans with global output reaching 130.9 million tonnes by 2022.
How many wild fish are required to produce one kilogram of farmed salmon in 1995?
In 1995, the fish-in-fish-out ratio stood at 7.5, meaning that for every pound of salmon harvested, 7.5 pounds of wild forage fish were consumed to produce it. This dependency creates a strain on forage fish populations like herring and sardines.
How much did parasites cost the global salmon farming industry in 2014?
In 2014, parasites were estimated to cost the global salmon farming industry up to 400 million Euros. This figure represents a significant portion of production value and has driven the industry to turn to vaccines and other disease management strategies.
What percentage of mangrove forests have been destroyed since 1980 due to shrimp farming?
Approximately 20 percent of mangrove forests have been destroyed since 1980 due to the expansion of shrimp farming. In Indonesia, over four decades of conversion have turned vast areas of mangroves into shrimp farms, many of which are abandoned within a decade.
How much water can a single oyster filter in a day?
A single oyster can filter 15 gallons of water a day. This filter-feeding capacity removes microscopic algal cells and extracts nitrogen and phosphorus from the system to improve water quality and restore eutrophic conditions.
The high density of fish in aquaculture cages creates a breeding ground for disease, with sea lice and viral pathogens causing widespread mortality and economic loss. In 2014, parasites were estimated to cost the global salmon farming industry up to 400 million Euros, representing a significant portion of production value. To combat these threats, the industry has turned to vaccines, with over 24 vaccines available for fish and one for lobsters, replacing the heavy use of antibiotics that plagued the sector in the 1990s. The development of DNA vaccines and mRNA technology offers new hope for preventing disease without the environmental risks associated with chemical treatments. However, the reliance on netting materials like nylon and polyester introduces another layer of complexity, as these materials can degrade and contribute to marine debris. Copper alloys have emerged as a solution to biofouling, providing antimicrobial properties that keep nets clean and reduce the need for frequent replacements, but the transition to sustainable materials remains an ongoing challenge.
The Mangrove Cost
The expansion of shrimp farming has come at a devastating price to coastal ecosystems, with approximately 20 percent of mangrove forests destroyed since 1980. In Indonesia, over four decades of conversion have turned vast areas of mangroves into shrimp farms, many of which are abandoned within a decade due to toxin build-up and nutrient loss. The external costs of this destruction far exceed the economic benefits, as the loss of mangroves eliminates critical habitats for marine life and removes natural barriers against storms. Whole-lake experiments in Ontario, Canada, have shown that cage aquaculture can lead to dramatic reductions in dissolved oxygen and significant increases in ammonium and phosphorus, driving eutrophication in freshwater systems. The waste from a single farm with 200,000 salmon can discharge more fecal waste than a city of 60,000 people, polluting pristine coastal ecosystems and threatening the biodiversity of the surrounding waters.
The Shellfish Salvation
While some forms of aquaculture cause environmental harm, shellfish farming offers a path toward ecological restoration. A single oyster can filter 15 gallons of water a day, removing microscopic algal cells and extracting nitrogen and phosphorus from the system. This filter-feeding capacity improves water quality and can help restore eutrophic conditions that threaten marine life. In Western Australia, a commercial sea ranch was established in Flinders Bay using 5,000 concrete units called abitats, which host 400 abalone each and feed on naturally growing seaweed. This approach has led to the recovery of local fish populations, including dhufish, pink snapper, and wrasse, demonstrating that aquaculture can be a tool for ecosystem enrichment. The industry has also seen the development of integrated multi-trophic aquaculture, where the waste from one species becomes the food for another, creating a balanced system that minimizes environmental impact while maximizing production.
The Future of Fish
The aquaculture industry is on the brink of a technological revolution, with innovations like recirculating aquaculture systems and genetically modified salmon promising to reshape the future of food production. The AquAdvantage salmon, which reaches full size in 16 to 28 months instead of the normal 36 months, consumes 25 percent less feed and has been reviewed by the FDA as having no significant impact on the environment. Meanwhile, scientists are developing low-salinity recirculating systems that allow saltwater fish like pompano to be raised in tanks with only 5 parts per thousand salinity, reducing the risk of disease transmission and nutrient pollution. The use of geothermal energy in countries like China, Israel, and the United States enables year-round fish growth, with California farms producing 4.5 million kilograms of fish annually. As the industry continues to evolve, the focus is shifting toward sustainability, with a growing emphasis on plant-based feeds, vaccines, and integrated systems that mimic natural ecosystems.