Energy economy of salmon aquaculture in the Baltic sea

Abstract

/ Resource utilization in Atlantic salmon aquaculture in the Baltic Sea was investigated by means of an energy analysis. A comparison was made between cage farming and sea ranching enterprises each with yearly yields of 40 t of Atlantic salmon. A variety of sea ranching options were evaluated, including (a) conventional ranching, (b) ranching employing a delayed release to the sea of young smolts, (c) harvesting salmon both by offshore fishing fleets and as they return to coastal areas, and (d) when offshore fishing is banned, harvesting salmon only as they return to coastal areas where released. Inputs both from natural ecosystems (i.e., fish consumed by ranched salmon while in the sea and raw materials used for producing dry food pellets) and from the economy (i.e., fossil fuels and energy embodied in economic goods and services) were quantified in tonnes for food energy and as direct plus indirect energy cost (embodied energy). The fixed solar energy (estimated as primary production) and the direct and indirect auxiliary energy requirements per unit of fish output were expressed in similar units. Similar quantities of living resources in tonnes per unit of salmon biomass output are required whether the salmon are feeding in the sea or are caged farmed. Cage farming is about 10 times more dependent on auxiliary energies than sea ranching. Sea ranching applying delayed release of smolts is 35-45% more efficient in the use of auxiliary energies than conventional sea ranching and cage farming. Restriction of offshore fishing would make sea ranching 3 to 6.5 times more efficient than cage farming. The fixed solar energy input to Atlantic salmon aquaculture is 4 to 63 times larger than the inputs of auxiliary energy. Thus, cage farming and sea ranching are both heavily dependent on the productivity of natural ecosystems. It is concluded that sustainable development of the aquaculture industry must be founded on ecologically integrated technologies which utilize the free production in marine ecosystems without exhausting or damaging the marine environment.

The Societal Value of Wetland Life-Support

“…due to problems with drinking water support to Gotland's capital there are plans to build a pipeline to a distant lake, one of the few remaining lakes -the Bastetrask-on the north-eastern part of the island; prior to exploitation the largest lake by area was situated within the Martebomire, and there were additional smaller lakes; it is hard to tell whether the additional water needs of the capital could have been supplied by these lakes without causing many of the environmental effects discussed in the paper; the higher cost assumes that this would have been possible, represented by a reduction by 15 per cent assumed to be the cost for a pipeline to the Martebomire. (Folke, 1988), which is about 1-2 tons; the value of this catch is substracted from the 1955 value; present sport fishing values are not considered.…”

Passing the Panda Standard: A TAD Off the Mark?

“…Intensive aquaculture is heavily reliant on fossil fuel energy inputs (Folke 1988) because of the numerous steps involved in production of complete fish feed (production of machines, fertilizers, pesticides, and ships to produce feed ingredients; the subsequent manufacturing processes to which they must be subjected; and the transportation of these ingredients over long distances), which all require combustion of hydrocarbons (Papatryphon et al 2004). Intensive tilapia culture also possesses a high degree of dependence on external ecosystems, requiring resources from large ecosystem areas outside the farm to produce its feed, to assimilate its nutrient wastes, and to maintain dissolved oxygen (Berg et al 1996).…”

Energy Return on Investment for Aquaponics: Case Studies from Iceland and Spain

“…The EROI methodology has previously been used to study fish production; for example, salmon farming has been shown to return approximately 0.15:1 unit of edible protein energy for each unit used in the production process, compared to values of 0.012:1 to 0.056:1 in this study (Folke 1988;Tyedmers 2004). From industrial fisheries, the EROI is quite dependent on the equipment used in the process.…”