Narrative reviewindependent cross-checkabstract checked★ key study I-FSH-114 in-depth review
Aquaculture 20 years on
A 20-year retrospective review of global aquaculture.
Overview
Naylor RL et al.. Nature 2021 · PMID 33762770 · DOI 10.1038/s41586-021-03308-6
Fish farms now need less wild fish per kilogram of farmed fish, but still rely on marine feed ingredients.
Does the study support the specific claim? Partly · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Review 20 years of aquaculture.
- How was the study done?
Narrative review.
- How many people, animals or samples were studied?
Global.
- What was actually found?
Lower fish-in-fish-out ratio; persistent marine dependence.
- How large was the observed effect?
Not in abstract.
- What do the results mean in everyday life?
The feed problem has shrunk but not disappeared.
- What are the study's limitations?
Abstract only.
- What does it say about Elawady's specific claim?
The claim is dated.
- Do the results apply to Germany and Europe?
High.
- What can explicitly not be concluded from this study?
The net balance for salmon today.
Scientific in-depth review
1. Full reference
- Authors
- Naylor RL et al.
- Journal
- Nature
- Year
- 2021
- Identifier
- PMID 33762770 DOI 10.1038/s41586-021-03308-6
- Verification
- verified – PubMed efetch 2026-10-26; Crossref checked
- Retracted
- no
- Corrections
Two publisher corrections (Nature 2021;593:E12 and 595:E36); content not read
- Extent checked
- abstract only
- Conflicts of interest and funding
Research Support, Non-U.S. Gov't
2. Research question
How has global aquaculture developed between 1997 and 2017?
3. Study design and population
- Study design
- Narrative review – Narrative review (20-year update of Naylor et al. 2000)
- Population
Global aquaculture
- Country
Global
- Period
1997-2017
- Sample size
Not applicable
4. Methods and endpoints
- Exposure / intervention
Aquaculture practices
- Comparator
Situation in 2000
- Endpoints
Production, feed efficiency, fish-in-fish-out ratio, sustainability
- Statistical methods
Descriptive
5. Actual results
- Results
'Major gains have also occurred in aquaculture feed efficiency and fish nutrition, lowering the fish-in-fish-out ratio for all fed species, although the dependence on marine ingredients persists and reliance on terrestrial ingredients has increased.' Inland aquaculture, especially in Asia, contributed most to production volumes and food security.
- Absolute risks
not applicable
- Authors' conclusion
Governance, technology and management improved in many cases; pathogens, parasites and feed remain challenges.
6. Strengths
- Authoritative update by the authors of the 2000 review
7. Weaknesses
- Narrative; abstract only; no net fish-balance figures read
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
Narrative review.
9. Assessment of the statistical interpretation
10. Relevance to the specific claim
C-FSH-11: fish-in-fish-out ratio lowered for all fed species; dependence on marine ingredients persists.
11. Independent contrary findings
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Weakens the present-tense claim without fully refuting it.
| 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 | consistent |
| 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 with mixed or unclear results