Tag Archives: aquaculture

What Shrimp and Beef Have in Common? carbon footprint

Shrimp farms tend to occupy coastal land that used to be covered in mangroves. Draining mangrove swamps to make way for aquaculture is even more harmful to the atmosphere than felling rainforest to provide pasture for cattle. A study conducted in 2017 by cifor, a research institute, found that in both these instances, by far the biggest contribution to the carbon footprint of the resulting beef or shrimp came from the clearing of the land. As a result, CIFOR concluded, a kilo of farmed shrimp was responsible for almost four times the greenhouse-gas emissions of a kilo of beef

Eating wild shrimp is not much better: catches are declining around the world as a result of overfishing. Trawlers can pull as much as 20kg of by-catch from the sea for every kilo of shrimp. And reports abound of the appalling treatment of workers on shrimp-fishing vessels, including human-trafficking and child labour. When UN investigators interviewed a sample of Cambodians who had escaped virtual slavery on Thai fishing boats, 59% of them reported seeing fellow crew-members murdered by the captain.


Most of the world’s shrimp and prawns come from Asia. The continent accounts for 85% of the farmed sort and 74% of the wild catch. Global sales were around $45bn in 2018 and are thought to be growing by about 5% a year. But the industry is controversial, not just because of its part in global warming. Razing mangroves also leaves coastal regions vulnerable to flooding. Many shrimp farms are unsanitary; ponds often have to be abandoned after a few years because of problems with disease and pollution.

All this has given one Singaporean company a brain wave. “Farmed shrimps are often bred in overcrowded conditions and literally swimming in sewage water. We want to disrupt that—to empower farmers with technology that is cleaner and more efficient,” says Sandhya Sriram, one of the founders of Shiok Meats. The firm aims to grow artificial shrimp, much as some Western firms are seeking to create beef without cows. The process involves propagating shrimp cells in a nutrient-rich solution. Ms Sriram likens it to a brewery, disdaining the phrase “lab-grown”….The hitch is that producing shrimp in this way currently costs $5,000 a kilo.

Excerpts from How artificial shrimps could change the world, Economist, Feb. 28, 2020

Survival of Bluefin Tuna

Japanese call bluefin tuna “the king of fish”. They eat about 40,000 tonnes of it a year—80% of the global catch. Demand is also growing rapidly elsewhere. Yet Pacific bluefin stocks are down by 97% from their peak in the early 1960s, according to a recent report from the International Scientific Committee, an intergovernmental panel of experts. (Japan disputes its findings.) In some places, fishing is three times the sustainable level, the committee says.

Aquaculture might seem to offer a way out of this impasse. But the bluefin is hard to breed in captivity. In the open sea, it can roam for thousands of miles and grow to over 400kg. It is highly sensitive to light, temperature and noise. Early attempts to farm it fizzled, but Kindai University persisted long after an initial research grant from the government ran out in the early 1970s. In 2002, funding itself from sales of other fish, it managed to rear adult tuna from eggs for the first time, rather than simply fattening up juveniles caught at sea. Now the chefs in Ginza can have a tuna zapped with an electric prod and yanked out of the university’s tanks on demand.

However, just 1% of the bluefin the university rears survive to adulthood. “We expect this to improve but it will take time,” predicts Shukei Masuma, the director of its Aquaculture Research Institute. Worse, the tuna gobble up lots of wild mackerel and squid. Scientists have experimented with soy-based meal and other alternatives. A company in south-western Japan said this month that it had managed to raise tuna using feed made of fishmeal, but it is costly and the fish are slow to thrive. Using wild fish for feed makes bluefin farming unsustainable, says Atsushi Ishii of Tohoku University. He sees aquaculture as a distraction from the thorny task of managing fisheries properly.

This debate is slowly seeping into the public consciousness. In 2014 the media made much of the decision of the International Union for Conservation of Nature, a conservation body, to put bluefin tuna on its “red list” of species threatened with extinction.

Excerpts from The Japanese Addiction to Tuna: Breeding Bluefin, Economist, Sept 24, 2016

Fishing to Death

Under international law the high seas, which span 64% of the surface of the ocean, are defined as “the common heritage of mankind”. This definition might have provided enough protection if the high seas were still beyond mankind’s reach. But the arrival of better trawlers and whizzier mapping capabilities over the past six decades has ushered in a fishing free-for-all. Hauls from the high seas are worth $16 billion annually. Deprived of a chance to replenish themselves, stocks everywhere pay the price: almost 90% are fished either to sustainable limits or beyond. And high-seas fishing greatly disturbs the sea bed: the nets of bottom trawlers can shift boulders weighing as much as 25 tonnes….

A fresh approach is needed. Slashing fishing subsidies is the most urgent step. In total these come to $30 billion a year, 70% of which are doled out by richer countries. By reducing fuel costs, subsidies bring the high seas within reach for a few lucky trawlers, largely from the developed world. Just ten countries, including America, France and Spain, received the bulk of the bounty from high-seas catches between 2000 and 2010, even though Africa has more fishermen than Europe and the Americas combined. That is unfair and short-sighted.

The next step is to close off more areas to fishing. As of 2014 less than 1% of the high seas enjoyed a degree of legal protection. A review of 144 studies published since 1994 suggests that to preserve and restore ecosystems, 30% of the oceans should be designated as “marine protected areas” (MPAs). Individual countries can play their part, by creating reserves within territorial waters: last year Britain created the world’s largest MPA, an area bigger than California off the Pitcairn Islands in the South Pacific. But to get anywhere near that 30% share, mechanisms must be found to close off bits of the high seas, too. The UN’s members have rightly agreed to work out how to do so…

So in parallel with efforts to protect wild stocks, another push is needed: to encourage the development of aquaculture, the controlled farming of fish. In 2014, for the first time, more fish were farmed for human consumption than were caught in the wild; farmed-fish output now outstrips global beef production. Unfortunately, feedstocks are often poor and storage facilities inadequate. …Eventually, efficient fish-farming will be the best guardian of stocks on the high seas.

Marine Management: Net Positive,  Economist, July  16, 2016, at 13