well. Lift boats cannot stay on site in all types of weather meaning that by
pre-emptively heading in before severe conditions, not only are no personnel at the
project site, but the feeders will not be getting filled on schedule, and fish will not
be growing. Taken together, the cost of at least two ASV vessels, crews to man
them, weekly supply boat runs, and the need for multiple feed buoys that must work
flawlessly, the platform option starts to look better in comparison. Except for one
hurricane evacuation during the Seafish project, the platform as a base of operations
allowed personnel to remain on site continuously for two years regardless of the sea
state and weather. This ability, combined with having a topside automated feed
system instead of feed buoy(s) and virtually limitless feed storage capacity on
multilevel decks begins to present a scenario where millions of kilograms of product could be cultured in the open ocean environment.
With regards to feeding, while a large buoy seems like an obvious alternative to
using a platform there are several issues that warrant consideration for the GoM
application of such a system. First, survivability of such a buoy is paramount since
having several hundred thousand kilos of fish in culture is irrelevant if there is no
way to reliably feed them. Designing a buoy that is able to maintain a specific
position relative to the cages during normal choppy Gulf conditions, frequent 3–
4 m seas, occasional 7+ m wave heights, and hurricanes is an engineering challenge at the very least. This technology is very expensive, but it has been
demonstrated at an offshore site in New Hampshire (Fig. 13.10) and some of this
research could be applied to future Gulf projects (Atlantic Marine Aquaculture
Center 2007, http://ooa.unh.edu/). Feed barges up to 450 ton are used in protected
waters (1–2 m) in Norway, Canada and Chile. Unfortunately, these pneumatic
feeders would not survive in the GoM environment. Other possibilities for feeding a
large scale farm include retrofitting a 40 m fishing vessel that can plug into a
mooring and feed distribution system to each cage. If a severe storm is approaching,
the vessel could detach and head back to port. Having a portable feeder would
allow you to conduct maintenance, refueling, personnel exchange and fill the feed
silos at a safe harbor instead of offshore. Offshore mariculture on a commercial
scale involving millions of dollars of equipment and fish will likely need to be
manned operations as well, a role that a platform and appropriate tender vessel
could accomplish. Without thinking along this economy of scale involving systems
that provide tens of thousands of cubic meters of water volume in which to grow
marine fish offshore, the benefits of operating in the open GoM will not be realized.
Experiences gained after many years working on offshore aquaculture systems
using platforms in the GoM can be distilled down into a partial list of some
important points.
1. Eliminate modes of failure in all parts of the production system. Keep it strong
and simple wherever possible as the offshore environment will reveal any
component weaknesses, usually very quickly and often catastrophically.
2. Ocean conditions and weather determine everything offshore so plans must be
made and adjusted accordingly. Nothing can be forced if conditions don’t allow
it as the ocean will always win in that situation.
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J.B. Kaiser and M.D. Chambers
pre-emptively heading in before severe conditions, not only are no personnel at the
project site, but the feeders will not be getting filled on schedule, and fish will not
be growing. Taken together, the cost of at least two ASV vessels, crews to man
them, weekly supply boat runs, and the need for multiple feed buoys that must work
flawlessly, the platform option starts to look better in comparison. Except for one
hurricane evacuation during the Seafish project, the platform as a base of operations
allowed personnel to remain on site continuously for two years regardless of the sea
state and weather. This ability, combined with having a topside automated feed
system instead of feed buoy(s) and virtually limitless feed storage capacity on
multilevel decks begins to present a scenario where millions of kilograms of product could be cultured in the open ocean environment.
With regards to feeding, while a large buoy seems like an obvious alternative to
using a platform there are several issues that warrant consideration for the GoM
application of such a system. First, survivability of such a buoy is paramount since
having several hundred thousand kilos of fish in culture is irrelevant if there is no
way to reliably feed them. Designing a buoy that is able to maintain a specific
position relative to the cages during normal choppy Gulf conditions, frequent 3–
4 m seas, occasional 7+ m wave heights, and hurricanes is an engineering challenge at the very least. This technology is very expensive, but it has been
demonstrated at an offshore site in New Hampshire (Fig. 13.10) and some of this
research could be applied to future Gulf projects (Atlantic Marine Aquaculture
Center 2007, http://ooa.unh.edu/). Feed barges up to 450 ton are used in protected
waters (1–2 m) in Norway, Canada and Chile. Unfortunately, these pneumatic
feeders would not survive in the GoM environment. Other possibilities for feeding a
large scale farm include retrofitting a 40 m fishing vessel that can plug into a
mooring and feed distribution system to each cage. If a severe storm is approaching,
the vessel could detach and head back to port. Having a portable feeder would
allow you to conduct maintenance, refueling, personnel exchange and fill the feed
silos at a safe harbor instead of offshore. Offshore mariculture on a commercial
scale involving millions of dollars of equipment and fish will likely need to be
manned operations as well, a role that a platform and appropriate tender vessel
could accomplish. Without thinking along this economy of scale involving systems
that provide tens of thousands of cubic meters of water volume in which to grow
marine fish offshore, the benefits of operating in the open GoM will not be realized.
Experiences gained after many years working on offshore aquaculture systems
using platforms in the GoM can be distilled down into a partial list of some
important points.
1. Eliminate modes of failure in all parts of the production system. Keep it strong
and simple wherever possible as the offshore environment will reveal any
component weaknesses, usually very quickly and often catastrophically.
2. Ocean conditions and weather determine everything offshore so plans must be
made and adjusted accordingly. Nothing can be forced if conditions don’t allow
it as the ocean will always win in that situation.
388
J.B. Kaiser and M.D. Chambers