Recirculating Aquaculture Systems - Comparison To Net Pen

Information about recirculating aquaculture systems and net pen systems has been excerpted from a Conservation Fund / SINTEF presentation whose authors include: Trod W. Rosten, Kristian Henriksen, Erik Skontorp Hognes, Brian Vinci and Steve Summerfelt. We include a direct link to the complete presentation below.

Recirculating Aquaculture Systems - Comparison To Net Pen Systems

Model Land-based Recirculating Aquaculture Systems farm (32 million US $ )

Invested equipment:

40,000 m3 of rearing tank volume
25,500 m2 of building area
2,500 m2 processing facility
885 m3/min of pumped RAS flow
Pumps and Piping
Screen filters
Biofilters
Gas Conditioning Filters
1.08 – 1.26 kg feed per m3 supply water
Feeding Systems
Backup Generators

Model Net Pen farm (12,3 million US $):

Two production sites, each with six net pen cages.≈587,000 m3 net-volume
120,000 m2 area footprint visible at sea
≈179,000 m2 area footprint incl. no thoroughfare zone
≈463,000 m2 area footprint incl. no fishing zone

Invested equipment:

3 licences
12 Floating rings (157m Ø)
24 nets (25 m deep)
2 mooring systems
2 boats
2 feed barges (150 Mtons)
12 camera systems
12 feed distributors
12 power systems

Model Land-based Recirculating Aquaculture Systems Farm

One production site for all life-stages
Four cohorts per year
Growth based on thermal growth coefficients from Freshwater
Institute growout trials, adjusted down by 10%:
1.1 for Fry
1.25 for Smolt
1.8 for Pre-growout
2.2 for Growout
Mortality per generation 16%

Feed conversion ratios:

0.75 for Fry
0.90 for Smolt
1.0 for Pre-Growout
1.1 for Growout
Overall Feed to Whole Fish Produced (kg/kg): 1.09

Rearing Density

80 kg/m3 maximum

Harvesting:

Time from first feeding to first harvest: 21 months
Harvest every week of the year
Each cohort harvested over 13 weeks
One grisle harvest at ~1.2 kg for 50% of males
Harvest in total: 3947 M.tons LWE, 3300 M.tons HOG (5% purge loss / 12% HOG loss)
Initial harvest weight (whole fish): 4.5 kg
Average harvest weight (whole fish): 5.1 kg
No downtime in the bio-plan

Model Net Pen farm:

2 production sites & 3 licences of 780 M.tons of maximum total biomass at sea.
Two transfers of smolts to sea annually, to one site
S1 at 1st of April, 100 grams, 520' smolts in three cages
S0 1st of August, 75 grams, 520' smolts in three cages
Growth based on the Skretting table, Specific Growth Rate
(SGR), adjusted down by 12 %.
Mortality per generation approximately 16,1 % (average in
Mid-Norway in 2011) (Norwegian Food Safety Authority 2011).
Economic feed conversion ratio: 1,27 (average in Norway over the last ten years) (Directorate of Fisheries 2013).

Rearing Density

25 kg/m3 maximum

Harvesting:

Time from first feeding to first harvest: 24 - 31 months
Time at sea before first harvest: 16 months
Harvest 8 months of the year
Harvest S1 from July to October
Harvest S0 from November to February
Harvest in total: 3 975 M.tons LWE, 3 299 M.tons HOG
(5 % purge loss /12 % HOG loss)
Average harvest weight (whole fish) : 4,5 kg
Two months of fallowing between production cycles

Recirculating Aquaculture Systems Profitability

Complete Presentation (Workshop #6)