Tag Archives: aquaculture

Turning leaked methane into fishmeal would turn a profit while helping the environment

The issue of methane pollution might become an asset in the future, thanks to new technology that can transform this potent greenhouse gas into fish food.

Image credits Sirawich Rungsimanop.

Approaches to converting methane into fishmeal have already been developed, the authors note, but the economic uncertainty during the pandemic has prevented its use to promote food security on any meaningful scale. The new study analyzes the method’s economic viability today. The main takeaway of the research is that methane-to-fishmeal conversion is economically feasible for certain sources of the gas and that other sources can be made profitable with certain improvements.

The approach can also be of quite significant help against climate change, the team adds, and is capable of meeting all the global demand for fishmeal, further reducing the strain we’re placing on natural ecosystems.

Untapped resource

“Industrial sources in the U.S. are emitting a truly staggering amount of methane, which is uneconomical to capture and use with current applications,” said study lead author Sahar El Abbadia, a lecturer in the Civic, Liberal and Global Education program at Stanford.

“Our goal is to flip that paradigm, using biotechnology to create a high-value product.”

Carbon dioxide is the best-known greenhouse gas, and currently the most abundant one in the Earth’s atmosphere. That being said, methane is another important player in our current climate woes. Methane is estimated to have 85 times the global warming potential of CO2 over a 20-year period, and at least 25 times as great a potential over a 100-year period. Methane also represents a direct hazard to public health as concentrations of this gas are increasing in the troposphere (the lower layer of the atmosphere, where people live). An estimated 1 million premature deaths occur worldwide, per year, due to respiratory illnesses associated with methane exposure.

The problem posed by methane is also increasing over time: the relative concentration of this gas in the atmosphere has been increasing twice as fast as that of CO2 since the onset of the Industrial Revolution, the team explains. Although there are natural sources of atmospheric methane, mostly through the decomposition of organic matter and from digestive processes, the lion’s share of that increase is owed to human-driven emissions.

Methanotrophs, bacteria that consume methane, have been explored as a potential solution in the past. If supplied with methane, oxygen, and certain nutrients, these bacteria produce a protein-rich sludge that can be used, among other things, to produce feedstock for fish farms. This process is already in commercial use by some companies; however, they are supplied by methane fed through gas distribution grids.

The authors note that capturing methane emissions — such as those from landfills, wastewater treatment plants, or leaked at oil and gas facilities — would be both cheaper and much more eco-friendly. Besides economic and environmental benefits, the shift from pumped to captured methane in the production of fishmeal would also help ensure humanity’s greater food security. The authors explain that seafood consumption has increased more than four times since the 1960s, with grave consequences for natural fish stocks.

Aquaculture (fish farms) now provide around half of the quantity of animal-sourced seafood consumed globally. Demand for seafood in the form of algae and animals is also estimated to double by 2050, the team adds, which will place increased strain on producers.

Against this backdrop, methane-sourced fish feed can represent an important asset towards food security in the future, and allow us to have the seafood we crave for minimal environmental impact.

Makes economic sense

Unused methane emissions in the U.S. from landfills, wastewater treatment plants and oil and gas facilities. Image credits El Abbadi, et al., (2021), Nature Sustainability.

In order to determine whether such efforts would also be economically-feasible, the team modeled several scenarios, each with a different source of methane used in the production of the fishmeal. These included natural gas purchased from commercial grids, as well as methane captured from relatively large wastewater treatment plants, landfills, and oil and gas facilities. For each scenario, they looked at a range of variables that would factor into a company’s bottom line, including the availability of trained labor and the cost of electricity used to keep the bioreactors running.

In the scenarios that involved methane capture from landfills and oil & gas facilities, the production cost for one ton of fishmeal would be $1,546 and $1,531, respectively. Both are lower than the 10-year average market price of such products, which sits at $1,600. In scenarios in which methane capture was performed at wastewater treatment plants, the cost per ton sat at $1,645, which is just slightly over the market average. However, the highest prices per ton were seen when methane was purchased directly from the commercial grid — $1,783 per ton.

Surprisingly enough, electricity was the single largest expense for all scenarios, representing around 45% of total costs on average. This means that areas with low electricity production costs could see significant decreases. The authors estimate that in states such as Mississippi and Texas, these costs would go down by around 20%, to an average of $1,214 per ton ($386 less than the 10-year average).

With certain improvements, such as bioreactors with more efficient heat transfer to reduce the need for cooling, production costs can be reduced even further. Even in the scenarios where wastewater treatment plants provided the methane, steps can be taken to reduce costs. For example, wastewater itself can be used as a source of nitrogen and phosphorus (key nutrients), as well as for cooling.

The team estimates that if manufacturers can bring the per ton production cost by 20%, there would be profits to be made even if all the supply of fishmeal today was covered using methane-produced materials with gas captured in the U.S. alone. With ever more reductions in cost per ton, such products could out-compete soybean and other crops for animal feed in general.

“Despite decades of trying, the energy industry has had trouble finding a good use for stranded natural gas,” said study co-author Evan David Sherwin, a postdoctoral researcher in energy resources engineering at Stanford. “Once we started looking at the energy and food systems together, it became clear that we could solve at least two long-standing problems at once.”

The paper “Displacing fishmeal with protein derived from stranded methane” has been published in the journal Nature Sustainability.

Farming algae could surprisingly help stave off deadly algae blooms

One possible solution to nutrient pollution and dangerous algal blooms could be seaweed farms, a new paper reports.

Image credits NOAA Great Lakes Environmental Research Laboratory / Flickr.

We don’t tend to think of “too much food” as a real problem, but for ecosystems around the world, it very much can be. Marine ecosystems especially suffer from nutrient pollution, as most of our waste tends to get dumped in the sea. This kind of pollution can become very deadly, as high levels of nutrients foster algal blooms which destroy water quality and deplete its oxygen — in short, they kill everything else around them.

New research at the University of California Santa Barbara suggests that aquaculture could help prevent such issues in the future.


“A key goal of conservation ecology is to understand and maintain the natural balance of ecosystems because human activity tends to tip things out of balance,” said co-author Darcy Bradley, co-director of the Ocean and Fisheries Program at the university’s Environmental Markets Lab.

Today’s reliance on industrial-scale farming on dry land is the main cause of nutrient pollution. Runoff from croplands contains huge levels of all kinds of nutrients (huge relative to their natural abundances) that plant life needs, including critical bottleneck nutrients such as nitrogen (a key ingredient in fertilizers). This input means that areas of the ocean can accumulate much higher quantities of nutrients than they would naturally.

A new study proposes seaweed farms as a possible solution, especially for nitrogen and phosphorus. Such farms would be able to scrub large amounts of nutrients even after they’ve made their way into the ocean at relatively low costs. The team identified over 63,000 square kilometers suitable for seaweed aquaculture in the Gulf of Mexico alone.

Algal blooms are dangerous primarily because of how fast they develop, and the huge amount of dead biomass they eventually produce. Algal blooms are, boiled down, communities of opportunistic algae and bacteria that rapidly expand in size when given the proper conditions. While they do produce oxygen while alive, the sheer volume of individuals dying in such a bloom at any one time consumes all the oxygen around them as they decay, which produces large hypoxic “dead zones” in which nothing else can live.

Seaweed farming could draw out at least part of these excess nutrients, which would limit the unchecked growth of algae and microbes. The oxygen output from these farms would also help prevent the appearance of dead zones.

The team looked at data regarding nutrient pollution in the U.S. Gulf of Mexico. It was selected as it’s the end-point for many waterways in the US — more than 800 watersheds across 32 states deliver nutrients to the gulf. A growing hypoxic dead zone has also been documented in the gulf, which was estimated to be just over 18,000 square kilometers back in 2019.

The authors analyzed data from the U.S. Gulf of Mexico, which they say exemplifies the challenges associated with nutrient pollution. More than 800 watersheds across 32 states deliver nutrients to the Gulf, which has led to a growing low-oxygen dead zone. In 2019, this dead zone stretched just over 18,000 square kilometers, slightly smaller than the area of New Jersey.

Using open-source oceanographic and human-use data, the authors pinpointed which areas would benefit from seaweed farming. Around 9% of the US exclusive economic zone in the gulf qualified, particularly areas off the west coast of Florida. But not all of that has to be farmed for us to see a positive impact.

“Cultivating seaweed in less than 1% of the U.S. Gulf of Mexico could potentially reach the country’s pollution reduction goals that, for decades, have been difficult to achieve,” said lead author Phoebe Racine, a Ph.D. candidate at UCSB’s Bren School of Environmental Science & Management.

Research such as this is important as countries around the world (the US included) already spend a lot of money trying to deal with nutrient pollution. Seaweed farming would complement such efforts at a very low cost, the team explains. Even better, seaweeds grown this way would have practical applications for industries ranging from fertilizers to biofuels, and agriculture.

The paper “A case for seaweed aquaculture inclusion in U.S. nutrient pollution management” has been published in the journal Marine Policy.

Carp mouths.

Fish farming could cover our demand for seafood one hundred times over, paper estimates

We’d only need 1% of the ocean’s surface to grow our seafood in farms, rather than capturing it from the wild. Not only would this allow marine ecosystems across the world to stabilize, but also increase food security, autonomy, and economic output.

Carp mouths.

Image credits Sabine Kroschel.

A team led by researchers from UC Santa Barbara, Working with scientists from the Nature Conservancy, UCLA and the National Oceanic and Atmospheric Administration, have published the first global assessment of marine aquaculture potential. According to their results, we don’t need to fish wild fish any longer — we could simply grow them in farms.

Fish farming is one of the fastest growing sectors of the food industry, already producing more biomass than “wild seafood catches and beef production,” the team writes. And there’s a lot more room to expand. Aquaculture could offer the resources to address our increasing food security concerns around the world, the team says, if we recognize its potential and work towards realizing it. Earth’s oceans are peppered with farming “hot spots,” they report, that could be developed to produce some 15 billion tons of fish each year, over 100 times the current global demand for seafood.

“There is a lot of space that is suitable for aquaculture, and that is not what’s going to limit its development,” said lead author Rebecca Gentry, Ph.D.

“It’s going to be other things such as governance and economics.”

Realistically though, we won’t carpet our oceans with farms. But even if we only develop the most productive areas, aquaculture could net the same quantity of seafood as all wild-caught fisheries produce globally using “only” 1% of the ocean surface.

Farms would also allow production to be more evenly spread out across the world. The lion’s share of today’s fish haul is produced in a handful of countries. But coastal countries could satisfy most if not all of their domestic demand for seafood by investing in aquaculture. In the case of the US, for the example, the team estimates national demand could be covered in full using only 0.01% of the states’ exclusive economic zone. It would also help the country cover its national seafood trade deficit, which now totals over $13 billion. Aquaculture would give us a workaround the issue of dwindling wild catches, which have been stuck at about 90 million metric tons for the past two decades now. Finally, growing our own fish, as opposed to taking it from the wild, would go a long way towards easing the strain we’re placing on marine ecosystems — both oceanic and local.

Fish in a bucket.

Image credits Daniel Perrig.

“Marine aquaculture provides a means and an opportunity to support both human livelihoods and economic growth, in addition to providing food security,” said co-author Ben Halpern, executive director of the UCSB-affiliated National Center for Ecological Analysis and Synthesis.

“It’s not a question of if aquaculture will be part of future food production but, instead, where and when. Our results help guide that trajectory.”

For the study, the team identified which areas of the oceans have conditions suitable for establishing fish farms by pooling together data such as ocean depth or temperature with the biological needs of 180 species of finfish and mollusks such as oysters and mussels. Then, they took out any areas that are already seeing human use which could come in conflict with farming efforts. Marine protected areas, shipping lanes, and places with depth in excess of 200 meters. The analysis, however, did not consider the political or social context in each country, which could end up placing additional constraints on aquaculture.

Still, even after these factors have taken their toll, we should be left with a lot of usable water. So we’ll have a lot of wiggle room to establish what farming practices work best for each country in regards to “conservation, economic development, and other uses,” according to Gentry. But it’s crucial to ensure that researchers, industry, and policy makes work together to ensure that fish farms are well placed and well managed, to make sure they won’t spread diseases to wild populations or otherwise impact their environments.

“Like any food system, aquaculture can be done poorly; we’ve seen it,” said co-author Halley Froehlich , referring to the boom and bust of shrimp farming in the 1990s.

“This is really an opportunity to shape the future of food for the betterment of people and the environment.”

The full paper “Mapping the global potential for marine aquaculture” has been published in the journal Nature Ecology & Evolution.