Scandinavian Silver Eel runs an eel farm at an industrial facility in Helsingborg, Sweden. Some of the eel is used for consumption – but 70 percent is restocked in the wild to help nature.

At Scandinavian Silver Eel’s Helsingborg facility, eels are growing in 70 small tanks. Photo: Scandinavian Silver Eel.

The European eel (Anguilla anguilla) is an amazing survivor, but like many other species of eel around the world it is threatened. Many eel dishes are regarded as delicacies, and overfishing has endangered the populations. The largest threat is barriers to migration, however; the natural migration routes the species have used for hundreds of years have become less accessible. The eel has been on the seafood red list in Sweden for a long time.

”Restocking farmed eels in Sweden and other countries is a way to help nature. We have restocked more than 40 million young eels over the years”, says Richard Fordham, CEO of Scandinavian Silver Eel.

Started as a waste energy project

”We began operations over 30 years ago, in industrial symbiosis with the chemical company Kemira Kemi in Helsingborg, Sweden. Their sulphuric acid plants generated 25°C waste water, which is almost the perfect temperature for growing eels. Eel farming was not the core business of the chemical company, of course, and in 2005, we almost had to close down. Eventually, me and four other people were able to buy the company, and we are still the owners of Scandinavian Silver Eel. When the sulphuric acid production diminished, the farm was changed to a system where freshwater was cleaned, oxygenated and recirculated between the tanks. We handle millions of eels every year, in about 70 tanks. The process requires a lot of pumps, fans and blowers – and, unfortunately, quite a lot of energy”, Richard Fordham says.

A unique species

”The eel is an interesting animal with many unique properties. In an eel farm, about 75 percent of the eels develop into small males, usually weighing less than 200 grams. In the wild, 95 percent develop into females, and grow bigger, reaching a weight of 1 – 1.5 kg. So, population density affects the sex ratio, and in the densely stocked tanks we usually end up with males. In Swedish lakes, populations are sparse and most eels become female”, Richard says.

”Most people have probably heard that the European eel journeys to the Sargasso Sea in the Atlantic, northeast of Cuba and Bahamas, to spawn. It is a distance of 7000 kilometers, and the migration takes six to nine months. The larvae (Leptocephali) make the return journey to Europe floating on the Gulf Stream. Before they reach shore, they develop into glass eels that swim into rivers. The glass eels then metamorphose and grow to become silver eels. Hydroelectric dams and other barriers can prevent the eels from migrating upstreams; the glass eels then remain where they are, until they starve or are killed by predators. When the mature silver eels prepare to make their journey back to the ocean after 10 – 20 years of growth, many – between 70 and 90 percent of them – fall victim to hydroelectric turbines”.

”In Nordic waters, it can take twenty years for an eel to become a sexually mature silver eel, ready to migrate to the Sargasso Sea. During the last decades, the number of glass eels returning from the Sargasso Sea has unfortunately dropped significantly, and the species is now severely threatened. That is why our restocking operations are so important”, Richard Fordham says.

Eel farming for consumption and restocking

The majority of the farmed eels – approximately one million glass eels every year – are restocked in Swedish waters. Photo: Scandinavian Silver Eel.

”We import glass eels from the river Severn in the United Kingdom, and grow them in our facility. After a three month quarantine period, more than 95 percent has survived; 70 percent of the glass eels are then restocked in rivers and lakes in Sweden and other European countries. The funding for this restocking has come from the EU, The Swedish Agency for Marine and Water Management, hydropower companies, fisheries management organizations, private individuals, fishermen and ourselves. All eel restocked on behalf of Swedish authorities is put in waters without migration barriers, so that it will be able to reach the Sargasso Sea and reproduce”.

”Scandinavian Silver Eel is the only company in Sweden that grows eel for consumption. About 30 percent of the eels end up as food. The production is certified, and amounts to about 120 tonnes annually (150 tonnes correspond to one million individuals). The Netherlands is the primary market, receiving about 90 percent of what we produce. There, small male eels are usually refined into smoked delicacies. The rest of the produce is sold in Sweden, to fish wholesalers, fish markets and smokeries”.

Responsible catching improves the situation

”The eel is a red-listed species, but we are not going to save it by not eating it. By responsibly catching them in England and growing them here in our tanks, we get eel for consumption and a sufficient surplus for restocking. We have delivered more than 42 million eels to Swedish waters during the last 30 years. More than 20 percent of them survive. We don’t know how many make it back to the Sargasso Sea. There are certain signs that the number of glass eels that return to Europe has increased in the last ten years. The eel situation is clearly improving, thanks to better methods of catching and handling. Meanwhile, a number of threats still remain, such as illegal glass eel capture. We can make a contribution by restocking more, but the legal fishery of glass eel has to be better protected”, Richard Fordham says.

The company is currently constructing an aquaponic facility where aquatic animals are cultivated together with plants. The fish production is the primary objective, and the plants are introduced to improve water quality and resource efficiency. The plants can also absorb nitrogen, phosphorus and carbon dioxide from the fish farming.

The article was published in March 2018.