Fin-fish farming: Optimizing a farm
Optimizing a fin-fish farm means increasing the efficiency with which a site license or discharge consent can be used. In most cases optimization requires the conversion of the greatest proportion of feed into harvested fish, with as little deterioration of pelagic or benthic conditions as possible. Farmed fish use oxygen and release ammonia. Where water movements are weak, the build-up of ammonia and the decrease in dissolved oxygen at a farm can adversely effect fish production. Uneaten fish food, and fish faeces, sink to the sea-bed and can harm animals, seaweeds or seagrasses here, as well as releasing gases harmful to fish and humans. In addition to lessening production, such impacts may lead a public environment manager to withdraw a licence or reduce the consented production.
Below, we list indicators that you can use for monitoring these effects. If you measure fish growth and condition at the same time, you will be able to make graphs showing the relationship between fish performance and environmental condition. These can help management. In addition, keeping track of seabed indicators shows whether conditions are degrading beneath cages.
| Environment/farm type/species | Indicator category | Scale | Indicators more to be added? links to be made | Comments |
| All pelagic environments, all species | Pressure | A:farm | Ammonia and ammonium Dissolved oxygen amongst cages, compared with reference conditions | These water column indicators are relatively cheap to measure continuously, using electronic probes. |
| All benthic environments, all species | Pressure and state/impact | A:farm | ITI, AMBI, Redox ... beneath cages, compared with reference conditions | These sea-bed indicators are relatively expensive to measure, requiring sampling by divers and, in some cases, specialized analyses |
In addition, there are several models of fish biology that you can use to explore ways to optimize production at a given level of feeding.
| Model (alphabetical order) | Model category: scale and relevance | Environment category | Fish type for which applicable | Tested at ECASA sites: |
| MOM | fish growth model in A (farm-scale) model that also predicts sea-bed and water-column effects | enclosed, and open coastal, waters | [cod, salmon,] sea-bass, sea-bream | Dalmar, Sounio, Cephalonia, Piran, Porto Ecolo, Bisceglie, [Creran, Vidlin] |
| BREAMOD | stand-alone fish growth model | Mediterranean open water | sea-bream | Bisceglie |
