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Aquaculture: effluent water quality from finfish farms

Indicator Specification Created 26 Feb 2007 Published 21 May 2010 Last modified 04 Sep 2015, 06:59 PM
Topics: ,
Indicator codes: SEBI 022

Assessment versions

Published (reviewed and quality assured)


Justification for indicator selection


  • Data availability on production levels and average values for conversion factors.
  • Established methodology.
  • Policy relevance (CFP).

Scientific references

  • No rationale references available

Indicator definition

Annual trend in release of nutrients into the marine environment as a result of aquaculture practices.


production is expressed in tonnes

Policy context and targets

Context description

The importance of aquaculture as a source of fish protein in the EU is increasing. In 2004 aquaculture contributed almost 19 % to the total fisheries production of EU-25 an increase of nearly 2 % over the situation in 2000. However, this was not due to an increase in aquaculture production, which has remained relatively stable since 2000, but due primarily to a decrease of nearly 10 % in the total fisheries production. One of the goals of the EU Common Fisheries Policy (CFP) is to take measures to mitigate the impact of aquaculture on the environment.

In general, effluent water quality is determined by the concentration of nutrients in the discharge water and hence by the amount of nutrients produced that will be discharged, and the flow rate of the effluent. In the case of aquaculture the production of nutrients that will be discharged in the marine environment is determined.

Relation of the indicator to the focal area

Aquaculture typically takes place in water of high quality. The principal measurable environmental pressures of aquaculture production are increased local organic matter, nitrogen and phosphorous which in turn may lead to locally increased Biological Oxygen Demand, eutrophication, and possibly algal blooms. In the absence of major improvements in industry practices, increased production is likely to be associated with increases in all these pressures and thus unsustainability (NB: some local systems may however have a higher carrying capacity than others).

Any localised degradation will lead to production problems on farms. Pressure from nutrients from intensive cultivation in marine and brackish water is becoming significant in the context of total nutrient loadings to the coastal environment. Although the environmental pressure from aquaculture will continue to grow as European aquaculture production expands, the rate of increase may be mitigated substantially by adoption of more sustainable management practices and production techniques.


No targets have been specified

Related policy documents

No related policy documents have been specified

Key policy question

What are the main trends in aquaculture across Europe?


Methodology for indicator calculation

The actual nitrogen and phosphorus discharge can be estimated by modelling the nutrient production by aquaculture operations by applying the appropriate conversion factors.

The proportion of aquaculture production which results in nutrient waste can be based upon the mid-range of values of 55g N released per kg production (5.5 %) and 7.5g P/production Kg (0.75 %) for finfish marine and brackish water production in the Atlantic and (66g N /production Kg (6.6 %) and 3g P /production Kg (0.3 %) in the Mediterranean.

Otherwise a formula can be used for Nitrogen

  • Discharged nitrogen = Feed nitrogen -- ish nitrogen
  • where Fish nitrogen = Total fish production * Protein level in fish/6.25
  • Feed nitrogen = Protein level /6.25 * Amount of feed
  • Amount of feed = Total fish production * Feed conversion rate

The total EU production is determined using FAO statistics.

Feed conversion rate and Protein level in the feed can be collected among fish feed manufactures as they have not been systematically documented.

Protein level in the fish can be obtained from scientific the literature.

Further methodological detail can be found in the specification sheet for CSI 033 at

Methodology for gap filling

No methodology for gap filling has been specified. Probably this info has been added together with indicator calculation.

Methodology references

Data specifications

EEA data references

  • No datasets have been specified here.

Data sources in latest figures


Methodology uncertainty

No uncertainty has been specified

Data sets uncertainty

No uncertainty has been specified

Rationale uncertainty


Calculations are based on conversion factors and statistics on:

Total fish production, Feed conversion rate, Protein level in the feed, and Protein level in the fish. All but the first are species specific and average values have to be derived.

The impact of nutrient release is site specific, depending on widely varying production practises, and local conditions coupled with the assimilative capacity of different habitats.

Further work

Short term work

Work specified here requires to be completed within 1 year from now.

Long term work

Work specified here will require more than 1 year (from now) to be completed.

Work description

SUGGESTIONS FOR IMPROVEMENT Feed conversion rates, protein level in the feed, and Protein level in the fish should become available at least for the main species in aquaculture and key culture systems. Critical levels should be set where possible (but effects of nutrients are very site specific). In the future the indicators could encompass the rest of aquaculture related pressures into the environment such as escapes and increases in pathogen density, chemotherapeutants and antibiotics, increased demand for feed inputs, interactions with the seafloor (sediment quality and effect on benthos), non‑native species. Extension to other aquaculture other than finfish.

Resource needs

No resource needs have been specified


Not started


2099/01/01 00:00:00 GMT+1

General metadata

Responsibility and ownership

EEA Contact Info

Katarzyna Biala


European Environment Agency (EEA)


Indicator code
SEBI 022
Version id: 1
Primary theme: Biodiversity Biodiversity


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Frequency of updates

Updates are scheduled every 2 years


DPSIR: Pressure
Typology: N/A
European Environment Agency (EEA)
Kongens Nytorv 6
1050 Copenhagen K
Phone: +45 3336 7100