Scope
This record documents how eels are exploited within globally established animal-use systems. It describes dominant practices across wild capture fisheries, aquaculture production, juvenile capture (glass eel fisheries), international wildlife trade, seafood processing industries, biomedical and aquaculture research, and byproduct processing, independent of country-specific regulation or culinary traditions.
Differences in scale, enforcement, and legal status are documented in country records. System-specific mechanisms are documented within industry records.
Species context
Photo by Lance Anderson
“Eels” commonly refers to several species of elongated, snake-like fish within the genus Anguilla, including the European eel (Anguilla anguilla), Japanese eel (Anguilla japonica), and American eel (Anguilla rostrata). These species share complex migratory life cycles that connect freshwater, coastal, and oceanic environments.
Eels possess developed sensory systems adapted to low-light aquatic environments and demonstrate behaviours including shelter seeking, migration, foraging, and spatial navigation. They are capable swimmers and undertake long-distance migrations during their life cycle.
A defining biological characteristic of eels is their catadromous life cycle. Adult eels migrate thousands of kilometres to spawn in oceanic spawning grounds (such as the Sargasso Sea for European and American eels). Their larvae drift with ocean currents before transforming into juvenile “glass eels,” which migrate into rivers and freshwater systems where they grow into adult eels.
These characteristics establish eels as migratory aquatic animals whose life cycles depend on large-scale ecological connectivity between ocean and freshwater habitats.
Natural versus exploited lifespan
Natural lifespan
In natural conditions, many eel species can live 15–40 years, depending on species and environmental conditions.
Lifespan under exploitation
Within exploitation systems, eels are typically killed far earlier:
- Aquaculture production: slaughtered once they reach market size, typically after several months to a few years in captivity
- Wild capture fisheries: killed shortly after capture
- Glass eel trade: juveniles are captured and raised in aquaculture systems before slaughter
The divergence between natural lifespan and exploited lifespan is determined by seafood market demand rather than biological longevity.
Systems of exploitation
Eels are exploited across multiple, overlapping systems:
- Wild capture fisheries
Adult and juvenile eels are harvested from rivers, estuaries, and coastal waters. - Glass eel fisheries
Juvenile eels (glass eels) are captured during migration from ocean to freshwater and sold into aquaculture systems. - Aquaculture production
Captured juveniles are raised in intensive farming systems until they reach market size. - International wildlife trade
Glass eels are traded internationally, including legal and illegal trade networks. - Seafood processing industries
Eels are processed into products such as grilled, smoked, or frozen seafood. - Biomedical and aquaculture research
Eels may be used in research studying fish physiology, aquaculture methods, and environmental impacts. - Byproduct industries
Eel bodies and waste materials may be processed into fish meal or other animal feed ingredients.
These systems rely on capture fisheries, aquaculture facilities, processing plants, and global seafood markets.
Living conditions across system types
Aquaculture systems
Eels raised in aquaculture are typically housed in tanks or pond systems where water conditions are tightly controlled. Large numbers of animals may be kept in relatively confined spaces.
Environmental conditions such as temperature, oxygen levels, and feeding schedules are manipulated to promote growth.
Artificial feeds are used to accelerate weight gain. Natural migratory behaviours and environmental complexity are absent.
Wild capture fisheries
Wild eels are captured using fishing gear such as:
- Nets
- Traps
- Weirs installed in rivers during migration
Glass eels migrating upstream are captured in large numbers using fine nets.
Captured eels may be transported long distances to aquaculture facilities.
Across systems, the natural migratory life cycle of eels is disrupted.
Standardised lifecycle under exploitation
Unlike many aquaculture species, eel farming does not rely on fully controlled reproduction in captivity. Instead, exploitation systems typically follow this pattern:
- Capture of juvenile eels
Glass eels migrating from ocean to freshwater are captured from rivers and estuaries. - Transport to aquaculture facilities
Juveniles are transported domestically or internationally. - Growth phase in captivity
Eels are raised in tanks or ponds and fed formulated diets. - Harvesting
Eels are removed from tanks once they reach commercial size. - Slaughter and processing
Eels are killed and processed into seafood products.
Wild capture fisheries harvest adult eels directly without the aquaculture stage.
Chemical and medical interventions
Aquaculture systems may involve chemical and medical interventions, including:
- Antibiotics to control disease outbreaks
- Water treatment chemicals
- Anti-parasitic treatments
- Feed additives to promote growth
High-density farming environments increase the likelihood of disease transmission.
Killing processes
Eels are commonly killed during harvesting and processing through methods including:
- Decapitation
- Exposure to ice slurry or freezing
- Asphyxiation outside water
- Electrical stunning prior to processing
Processing may occur shortly after harvesting from aquaculture tanks or fishing vessels.
Labour impact
Eel exploitation industries involve labour associated with:
- Glass eel capture operations
- Aquaculture facility management
- Sorting, grading, and harvesting
- Seafood processing and packaging
Workers may face repetitive strain injuries, hazardous equipment exposure, and long working hours during fishing seasons.
Scale and prevalence
Eels are widely consumed seafood products in several regions, particularly East Asia and Europe.
The global eel industry relies heavily on the capture of wild juvenile eels to sustain aquaculture production. Demand for eel products has contributed to extensive fishing pressure on wild eel populations.
Ecological impact
Eel exploitation contributes to ecological disruption, including:
- Declines in wild eel populations due to intensive juvenile capture
- Disruption of migratory life cycles
- Habitat degradation in rivers and coastal systems
- Illegal trade and trafficking of glass eels
Many eel species have experienced substantial population declines associated with overfishing, habitat loss, and barriers to migration such as dams.
Language and abstraction
Eels are often described using culinary terms such as “seafood” or product-specific names associated with prepared dishes. These terms frame eels as food commodities rather than migratory animals removed from complex ecological life cycles.
Editorial correction notice
Eels are frequently framed as seafood products or aquaculture commodities. This record documents eels as migratory aquatic animals systematically captured, confined, farmed, transported, and killed within integrated fisheries, aquaculture, and international wildlife trade systems independent of culinary or commercial framing.