Strategies and Closed and Semi Closed Containment Systems
Closed and Semi Closed Containment systems form the basis for the future of salmon farming. There are a number of production techniques and technologies being examined world-wide to examine primarily ways that increase economic viability and decrease the high mortality and parasite loading of fish on farming sites.
The current and almost exclusive use of open net pen farms are increasingly becoming less desirable through a combination of high stock mortality and increasing costs involved in treating salmon for parasites and patogens.
The increased incidence of problems can be linked to increased water temperatures caused by climatic change, increased numbers of farmed fish at sea and overall decline in water quality in near shore and oceanic environments. The constant and effective arguments by environmental groups has also helped to force industry and regulatory bodies to examine more environmentally friendly options.
The present dominant type of farming involves the following steps which include the production of smolts to 70 Grams in freshwater flow through systems, although increasingly these are being replaced by RAS systems (Re-circulation Systems), on-growing of post smolts in open net cage farms at sea up to 5 kg.
The main development focus now appears to be either eliminating the sea residence period or to reduce the time that salmon are required to be at sea.
Closed and Semi Closed Containment : Reduce Residence Time In Ocean
In regard to the elimination of the sea residence period the preferred option appears to be a closed re-circulation system based onland. The preferred option would certainly be this system as the vast majority of problems affecting wild salmonids would be effectively addressed. Unfortunately industry and regulatory bodies appear to be less than impressed by the capital expenditure and operational costs involved.
Certainly there have been advances in the technologies involved but certain economic factors remain. It is probable that these factors may not pose problems in future if industry was to substantially move on-shore thereby facilitating an even playing field in regard to economics.
Production Strategies
In regard to production with a limited residence period a number of different options are certainly being examined by the industry with readily available incentives being offered by some regulatory bodies as is the case with onshore closed containment. Three possible scenarios are mentioned:
- Smolt production in RAS on land to normal size, post smolt ongrowing to 1 kg in semi closed containment system at sea, ongrowing of salmon to 5 kg in open net cages.
- Smolt production in RAS to normal size, post smolt growth to approximately 1 kg in semi enclosed containment system, ongrowing to 3 kg in open net cage farms, ongrowing to 5kg in semi closed containment system.
- Smolt production in RAS to 1kg, post smolt growth to approximately 3 kg in semi closed containment system at sea, ongrowing to 5kg in open net cages.
There appears to be no desire to test the semi-closed containment systems to grow the fish through entire production cycle at sea.
It is imperative that we do not accept entirely what the industry desires as they will only engage with technologies and production schedules which suit their business model. In Ireland our Department of Agrigculture, Fisheries and Food appears completely tied to open net cage farming reliant on the Marine Institute insistence that little if any damage is or indeed will occur to wild salmonids and near coast ecosystems.
Closed and Semi Closed Containment Systems
The following semi-closed and RAS technologies are related in the following videos, the majority of which are not as yet in full production but under test by various industry sources.
Hauge Aqua: Egg concept technology which effectively demonstrates the future direction of the industry. Salmon Watch Ireland would be very interested in observing the roll out of this technology. Marine Harvest have been granted four development licences for this technology which is expected to be in operation in 2019.
Water borne disease control may be an issue but the prototype does include filtration and water treatment facilities. Sea lice would certainly be largly eliminated by virtue of intake water being taken from depth where sea lice are generally not present and the technology can also claim to be environmentally sound in that food pellets can be collected within the farm and not disposed of at sea. Operational economics can also be positively impacted due to the unique feeding system which improves food to growth ratio. Overall an excellent product and we await the results of trials in Norway.
