Danish trout farming is restricted by public regulations of emissions to water and the extent of trout production in farms is independent of the market demand. Hence, environmental impacts associated with farmed trout are determined by the products, which they substitute rather than the processes associated with production.
It is unknown what kinds of food are most likely to be substituted by farmed trout. Until more knowledge becomes available any food product such as chicken, pork, cattle, farmed fish, vegetables or bread or combination hereof can be appropriate. Thus, the potential environmental impacts associated with a demand for farmed trout equals the environmental impacts associated with for instance some of the following products.
| Possible substitutes of farmed trout |
|
Pork (tenderloin, ham, steaky bacon, minced meat etc.) Cattle (tenderloin, fillet, steak, knuckle shank, round, minced meat etc.) |
Trout farmers are reducing the environmental load per produced unit due
to intensified water purification at the farms in these years and it is
possible that production can be increased to reach the market demand in
the future without violating the legal restrictions. The
main processes influenced by a demand for trout
are
shown in the figure below,
in an envisioned
scenario that the extent of
trout production becomes independent of the environmental regulation and
determined by the market demand as a result of improved environmental
management.
|
|
| Figur 1:Market based product chain diagram for trout production covering the most important processes in terms of contribution to global warming, provided that trout production is regulated by market demand in a possible future. Boxes refer to production processes. Names of grey boxes refer to the main product of the processes. Red arrows represent material or energy transfer between two processes; green arrows represent saved material or energy transfer as a result of displacements; green lines represent displacements and red lines represent avoided displacements. Further details can be found in the LCA model. |
In the scenario, trouts are raised in ponds with comprehensive wastewater treatment and 100% water recirculation. The trouts are fed with trout feed produced from fish meal and a number of other ingredients. The fishmeal is produced from sand eel in the present example but could also be other kinds of industrial fish.
It has been assumed that fish oil produced as a side product in fishmeal production displace rapeseed oil (1:1) and (Landbrugets rådgivningscenter, 2000) that rape meal co-produced with rapeseed oil displace a mix of soy meal and spring barley1). Environmental impacts associated with the co-products have been eliminated by system expansion, explaining the red and green lines.
The environmental impacts potentials associated with trout demand in an envisioned scenario that trout production is determined by the market demand are shown in the table below. All data are provided per kg of living trout or kg of trout fillet.
| Impact category | Unit |
Living trout ex farm |
frozen trout fillet ex slaughterhouse |
frozen trout fillet ex retail |
|
Global warming |
g CO2-eq. |
1800 |
4090 | 4470 |
|
Acidification |
g SO2-eq. |
9.3 |
13,5 | 14 |
| Nutrient enrichment | g NO3-eq. | 260 | 82 | 83 |
| Photochemical smog | g ethene eq. | 1.0 | 1.5 | 1.6 |
| Land use | m2 year | 1.1 | 1.2 | 1.2 |
| Location in database: Material/Food from primary sectors/Aquraculture/trout (Standard) from trout pond farm or Material/Food from industery/Food from fish industry/trout, slaughtered, frozen (Market regulated) or Material/Food from supermarket/Freezing counter/Trout, frozen, in supermarket (market regulated) |
References
Landbrugets
rådgivningscenter (2000). Tal fra Fodermiddeltabellen, Raport nr. 91.
---------------
1) Spring barley's
contribution to global warming is too limited to be included in the figure.