EelFreshwater eel, unagi

Details

  • Latin name: 
    Anguilla japonica, A. anguilla, A. rostrata
  • Seafood type: Eel
  • Harvest method: Open net pen, Pond
  • Region: Asia
  • Wild/Farmed: 
    Farmed
Status: 
Not Recommended

Freshwater Eel

Credit: FAO
Sustainable alternatives: 
US Farmed Channel catfish is a sustainable seafood option.
Sustainability concerns: 
There are concerns with the amount of marine resources required and the use of wild broodstock in freshwater eel farming.
Freshwater eel aquaculture methods vary from closed recirculating systems to open net pens and ponds. All of the options are considered unsustainable, however some options (closed recirculating tanks) are less damaging than others.
Life History and Population Status: 
The three wild populations; American eel, Japanese eel and the European eel are all experiencing severe declines, due mostly to habitat loss, pollution and overfishing. Freshwater eel is an important food item in asian countries, so to meet demand aquaculture of freshwater eels has grown to 90% of the market.
Management: 
Management of freshwater eel aquaculture is very poor. The majority of the eels are farmed in open-net pens and not enough is being done to protect the wild eel populations and surrounding environment.
Impact on Other Species: 
Escapees from open-net pen farms and disease transfer pose a threat to wild populations of freshwater eels. This is especially true for this aquaculture industry because broodstock is taken from the wild and is also shared between farms, countries and continents. This puts further stress on wild populations by removing young eels and provides an easy avenue for the transfer of diseases between farms. Freshwater eels are a carnivorous species and their farming requires a high use of marine resources. 2.5 tons of wild fish are required to produce a ton of freshwater eels.
Habitat and Ecosystem Impacts: 
Flow-through systems release waste into the surrounding environment. The waste settles below net pens, often smothering sensitive habitats. Antibiotics and other chemicals used in culture operations are also released into the surrounding habitat. Closed recirculation systems allow for the constant filtration and removal of solids, effective effluent treatment and low discharge rates. The risks of disease transfer and/or potential escapees are greatly reduced.

Notes:

  • No or little concern in this area.
  • Significant concern in this area.
  • Area under study.