European catfish: Danger of consumption – What anglers need to know about PCB

Introduction

The European catfish ( Silurus glanis ) is a giant of European waters - revered by anglers for its strength, feared by prey fish for its size. But this iconic predator carries an invisible legacy of industrial history: polychlorinated biphenyls (PCBs) . These persistent pollutants, once used in transformers and paints, still pollute rivers and lakes today - and accumulate particularly in large catfish. This report explains why anglers should be cautious with this fish, what risks PCBs pose and how to act responsibly.

PCB – The toxic legacy in our waters

What are PCBs?

Polychlorinated biphenyls (PCBs) are synthetic chlorine compounds that were used in industry worldwide between 1930 and 1980. Despite being banned in 2001 by the Stockholm Convention, they can still be detected in sediments.

Why are PCBs dangerous?

• Persistence: PCBs hardly degrade – they survive in sediments for up to 100 years (Federal Environment Agency, 2023).
  - Bioaccumulation: The fat-soluble substances accumulate in the fatty tissue of organisms.
  - Biomagnification : The higher an animal is in the food chain, the greater the PCB contamination.

Health consequences for humans:

- Cancer risk: PCBs are considered carcinogenic (IARC, Group 2A).
- Hormonal disorders: They act as endocrine disruptors and can impair thyroid functions.
- Developmental disorders: In children, PCBs are suspected of causing neurological damage (WHO, 2022).

The Catfish – A Bioindicator for PCB

Why the catfish is particularly affected:

1. Longevity: Catfish can live for over 80-90 years – the older they are, the more time they have for PCB accumulation.
2. Position in the food chain: As a top predator, the catfish eats other fish, crabs and mussels that have already accumulated PCBs.
3. Benthic diet: Catfish often stay on the bottom of water bodies, where sediments containing PCBs are deposited.

Current data from Europe:

- Lake Bourget (France): A 2023 study shows that catfish over 168 cm in length can exceed the EU limit of 125 ng/g PCB (Foucher et al., 2023).
- Rhine and Danube: In industrial areas such as the Rhine-Main Delta, PCB levels of up to 300 ng/g have been measured in catfish (EEA, 2021).
- Baltic region: In the Baltic Sea, a historical PCB hotspot, the values ​​for catfish are even higher (HELCOM, 2022).

Fish size decides:

- In catfish, the PCB concentration increases exponentially with body size.
- Rule of thumb: For every 10 cm of length, the load increases by 15-20% (study in Lake Geneva, 2020).

Risks for anglers – What you need to consider

Consumption warnings in Europe:

- Germany: The Federal Environment Agency advises against eating catfish over 1 meter from the Rhine , the Elbe and the Danube .
- France: In the Rhône Basin , a catch limit for catfish >150 cm has been in force since 2022.
- EU Regulation (1259/2011): The limit for PCB in fish is 125 ng/g (sum of 6 PCB congeners).

Practical tips for anglers:

1. Catch & Release : Large catfish (>150 cm) should be released – they are ecologically valuable and pose a health risk if consumed.
   2. Water check: Before fishing, check regional PCB warnings – e.g. using the LAWA map (State Working Group on Water).

The Role of the Catfish in the Ecosystem

Ecological significance:

- The catfish regulates fish populations and keeps invasive species such as Black Sea gobies in check.
- As a “health police” it also eats carrion and sick fish and thus prevents the spread of diseases.

Why the catfish should not be demonized:

- Not a “pest”: The catfish is a natural part of European waters – its spread is often the result of human intervention (e.g. canal construction).
- Protection status: In some countries the catfish is on the red list of threatened species.

Solutions – How we can contain PCB

1. Sediment remediation:

- Re-stratification: PCB-containing sediments are covered with clean material (successfully carried out in Lake Zurich).
- Bacterial degradation experiments: Pilot projects use PCB-degrading bacteria (e.g. Dehalococcoides ).

2. Fisheries management:

- Size limits: bans on catching large catfish in contaminated waters.
- Monitoring: Regular PCB testing in commercial fish stocks.

3. Consumer education:

- Apps like “FishGuard” (developed by WWF) warn anglers in real time about polluted waters.

Summary

- PCBs are a hidden legacy of industry – the catfish acts as a bioindicator for this contamination.
- Size and origin determine the risk: Avoid the consumption of catfish from industrial regions!
- Anglers as ambassadors: By acting responsibly, we can protect the species and minimize health risks.

Last appeal:

The catfish is not a "problem fish" but a victim of human environmental sins. By taking its PCB contamination seriously, we are not only protecting ourselves but also the fascinating biodiversity of our waters.

Written by Vitali Dalke

Sources:

1. Study in Lake Bourget: Foucher, V. et al. (2023). Science of The Total Environment.
2. EU Regulation 1259/2011: Limit values ​​for PCBs in food.
3. Federal Environment Agency (2023): Guideline on PCBs in inland waters.
4. HELCOM (2022): Baltic Sea PCB Monitoring Report.
5. WWF FishGuard app: real-time alerts for anglers.