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AL > Fisheries & Aquaculture > New Technology > Marine Harvest Canada Marine Harvest CanadaProject DescriptionOne dimension of the experimental trial at the Cusheon Cove site, on Saltspring Island tested 6 closed containment net-bags built of a heavy gage plastic that is impermeable to water. This system is similar to traditional mesh nets in size and shape and hangs in the water from a steel frame. However, the impermeable nature of the material prevents water from flowing into or out of the bags, effectively isolating farm stock from the marine environment. The closed containment system was designed and manufactured by Future SEA Technologies Inc. To learn more, click the link below: Every bag has a hydraulic pump to move water into the bags. The water circulates in a spiral manner and eventually discharges through a central port in the bottom of the bag. Depending on the number and size of the fish in the bags, additional oxygen may be required. Construction of the facility was completed in the summer of 2001 at a cost of $1.3 million, and the trial took place over a 14 month period. This time frame provided an opportunity to develop management routines appropriate for the Future SEA system and local operating conditions, and yielded benchmark production and economic data. The other dimension of the trial project at Cusheon Cove involved feeds containing alternative oils and proteins, and evaluated their impact on fish production. Approximately half the cost of farmed salmon production relates to the cost of fish food, much of which is sourced from oil and meal derived from wild-caught fish stocks that farmers access through a global trading system. The theoretical advantages of alternative feeds are that they may reduce dependencies on fish meal and oil, and reduce overall costs of production. Comparative AnalysesMarine Harvest has completed a comparison of farm gate cost of production (COP) variations between the Future SEA system and the conventional system. Whereas the trials indicated minimal COP differences across several categories, including smolts, feed, power consumption, and labour, more significant variations were observed for other aspects, including operational expenses, oxygen, and depreciation. Overall, the COP for the Future SEA system was 29% higher than for the net cages. The higher costs for oxygen use were due to supply and transportation constraints, and those for operating expenses were a result of freight, cage maintenance, equipment rentals, and diving costs. The 29% variation in economic performance resulted in a difference of $0.85/kg harvested. A comparison of fish performance over the first several months revealed some differences:
No major differences were noted across other categories. Neither of the production units experienced escape events, and there did not appear to be any difference in escape potential between the systems. Waste and excess feed distribution beneath both systems was also similar. There were no clear differences in terms of predator interactions. Improvements in general husbandry practices and management routines would likely contribute to enhanced production performance for the Future SEA system, especially in terms of fish growth and feed conversion. Moreover, improved deliveries of oxygen supplies – both to the site and to fish in the SEA units – would reduce costs associated with oxygen, labour, and operating expenditures. All such improvements would likely narrow the economic gap between the Future SEA bags and the net-cages across these parameters. Similar to the findings for the Future SEA system, the feed trials at the Cusheon Cove site revealed minimal variance in production and environmental performance between the alternative feed group and the control diet group. Although fish growth was shown to be slightly better for the control group during early development stages, final growth rates were generally similar for both groups. The findings suggest a similar pattern for feed conversion ratios, which were very favorable for both groups. No differences in waste production levels were observed nor expected given the parity of feed conversion ratios. Finally, mortalities for fish in both groups were low, and fish health was also good throughout the production cycle. Picture Gallery
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