Narrative reviewindependent cross-checkabstract checked★ key study I-FSH-118 in-depth review
Fish farming still eats a lot of wild fish
A review of the global use of fishmeal and fish oil and the Fish In:Fish Out metric.
Overview
Majluf P et al.. Sci Adv 2024 · PMID 39413173 · DOI 10.1126/sciadv.adn5650
Farmed carnivorous species such as salmon and shrimp use most of the world's fishmeal and fish oil, made mainly from small wild fish; the usual efficiency metric hides this.
Does the study support the specific claim? Yes · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Review FMFO use and the FIFO metric.
- How was the study done?
Review.
- How many people, animals or samples were studied?
Global feed data.
- What was actually found?
Carnivorous aquaculture uses most FMFO; FIFO is misleading.
- How large was the observed effect?
Not in abstract.
- What do the results mean in everyday life?
Farming carnivorous fish still depends on wild fish.
- What are the study's limitations?
Abstract only.
- What does it say about Elawady's specific claim?
Supports the claim.
- Do the results apply to Germany and Europe?
High.
- What can explicitly not be concluded from this study?
Exact net balance per species.
Scientific in-depth review
1. Full reference
- Authors
- Majluf P et al.
- Journal
- Sci Adv
- Year
- 2024
- Identifier
- PMID 39413173 DOI 10.1126/sciadv.adn5650
- Verification
- verified – PubMed efetch 2026-10-26; Crossref checked
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
Does the Fish In:Fish Out metric correctly show decreasing dependence of aquaculture on wild fish?
3. Study design and population
- Study design
- Narrative review – Review of fishmeal/fish oil use and of the FIFO metric
- Population
Global aquaculture feed supply
- Country
Global
- Period
not stated in abstract
- Sample size
Not applicable
4. Methods and endpoints
- Exposure / intervention
Fishmeal and fish oil use
- Comparator
Industry FIFO claims
- Endpoints
Wild fish use
- Statistical methods
Not stated in abstract
5. Actual results
- Results
'Aquacultured carnivorous species consume most of the world's fishmeal and fish oil (FMFO), which itself is primarily derived from small pelagic fish.' The FIFO metric is 'misleading' because it assumes constant yields, inclusion rates and feed conversion ratios; averaging carnivores and herbivores 'conceal[s] the high feed requirements of carnivore species'. Increasing use of by-products 'does not demonstrate a decreased use of wild fish'.
- Absolute risks
not applicable
- Authors' conclusion
Industry FIFO values understate the dependence of carnivorous aquaculture (salmon, shrimp) on wild fish.
6. Strengths
- Recent, critical analysis of the metric used to claim improvement
7. Weaknesses
- Abstract only
- Authors linked to ocean-conservation research; methods not seen
8. Risk of bias
- Orienting tool
- none applicable
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- not assessable
- Rationale
Review; abstract only.
9. Assessment of the statistical interpretation
10. Relevance to the specific claim
C-FSH-11: carnivorous aquaculture still consumes most fishmeal/fish oil from wild small pelagic fish; contests the 'decreasing dependence' interpretation of FIFO in I-FSH-114.
11. Independent contrary findings
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Supports the core of C-FSH-11; disagrees with industry-based FIFO trends.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | not assessable |
| Precision of results | not applicable |
| Directness | direct |
| Reproducibility | unknown |
| Consistency with the overall evidence | mixed |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
15. Linked fact checks
- Farming carnivorous fish species depletes the wild fish stocks used as feed rather than relieving pressure on the oceans. – Studies supporting the claim