that question has been no based on the experiences of the projects to date.
A comprehensive economic feasibility study on using oil and gas structures in the
GoM for mariculture concluded that at the present time it not likely to be a profitable venture (Kaiser et al. 2011a). Liability and decommissioning issues for the
structure itself have long been identified as the major impediments to mariculture
using platforms in the GoM and this situation remains true to the present (Dougall
1999; Kaiser et al. 2011a). The regulatory environment and permitting issues in
offshore waters of the US have hindered development for two decades and investors
have simply moved their offshore cage culture projects to other countries in many
cases (Upton and Buck 2010). Internationally, there are only a couple of locations
using dedicated platforms for mariculture production, one in the Mediterranean and
the other in Japan. The platform in each case has multiple cages attached to it and
acts as the operational center from which the growout systems are fed and maintained (Kaiser et al. 2011b). Considering the high energy environment, possibility
for hurricanes, platform cost and liability issues, logistical challenges, and economic reality of offshore mariculture, it is not surprising there are no cage systems
currently in the Gulf of Mexico.
That being said, it is the authors assertion that in the future a project with the
right location, substantial capital investment, experienced personnel, and a good
cage system will profitably grow fish in the Gulf of Mexico. The scenario will likely
involve multiple submersible cages near a platform with a crane that houses a
feeding unit capable of holding 200+ tons of feed which can be operated remotely if
required. The structure may or may not be associated with an energy company and
it may turn out that a platform put into place and designed specifically for a
mariculture project, while certainly expensive, might be a better long-term option.
The potential of refurbishing and reusing a decommissioned platform has also been
suggested (Kaiser et al. 2011b) and may offer some advantages with regards to the
liability issues that are associated with ownership.
An alternative to a platform proposed in the OAC final report is an aquaculture
support vessel (ASV) which could be a large catamaran style vessel or more likely a
lift boat type commonly used for nearshore maintenance on platforms (Bridger
2004). Several issues come to mind that make that option less attractive considering
the high energy real world conditions in the GoM. Lift boats are very slow vessels
(5–7 knots) that can only travel in decent seas—this complicates the logistics of
anything in the 30+ km range. Because of depth requirements, these are the most
likely areas for a cage project requiring tons of feed every day so faster crew boats
would be required weekly to transfer the feed to a lift boat on a continual basis. In
addition, once an operation is established with multiple cages and a substantial
investment in fish stock, there can be no interruptions due to lift boat vessel
maintenance, annual US Coast Guard inspections, and other mechanical issues.
Because of this need for continual operation a second, backup ASV would be
required for any large scale project that is conducted in GoM offshore waters.
Assuming the cage site is in the preferred 30–50 m water depth, the cost of lift
boats that can operate at these locations would be in the $5–20 + million dollars per
boat range and would require the expense of two rotating teams of crew members as
13 Offshore Platforms and Mariculture in the US
387
A comprehensive economic feasibility study on using oil and gas structures in the
GoM for mariculture concluded that at the present time it not likely to be a profitable venture (Kaiser et al. 2011a). Liability and decommissioning issues for the
structure itself have long been identified as the major impediments to mariculture
using platforms in the GoM and this situation remains true to the present (Dougall
1999; Kaiser et al. 2011a). The regulatory environment and permitting issues in
offshore waters of the US have hindered development for two decades and investors
have simply moved their offshore cage culture projects to other countries in many
cases (Upton and Buck 2010). Internationally, there are only a couple of locations
using dedicated platforms for mariculture production, one in the Mediterranean and
the other in Japan. The platform in each case has multiple cages attached to it and
acts as the operational center from which the growout systems are fed and maintained (Kaiser et al. 2011b). Considering the high energy environment, possibility
for hurricanes, platform cost and liability issues, logistical challenges, and economic reality of offshore mariculture, it is not surprising there are no cage systems
currently in the Gulf of Mexico.
That being said, it is the authors assertion that in the future a project with the
right location, substantial capital investment, experienced personnel, and a good
cage system will profitably grow fish in the Gulf of Mexico. The scenario will likely
involve multiple submersible cages near a platform with a crane that houses a
feeding unit capable of holding 200+ tons of feed which can be operated remotely if
required. The structure may or may not be associated with an energy company and
it may turn out that a platform put into place and designed specifically for a
mariculture project, while certainly expensive, might be a better long-term option.
The potential of refurbishing and reusing a decommissioned platform has also been
suggested (Kaiser et al. 2011b) and may offer some advantages with regards to the
liability issues that are associated with ownership.
An alternative to a platform proposed in the OAC final report is an aquaculture
support vessel (ASV) which could be a large catamaran style vessel or more likely a
lift boat type commonly used for nearshore maintenance on platforms (Bridger
2004). Several issues come to mind that make that option less attractive considering
the high energy real world conditions in the GoM. Lift boats are very slow vessels
(5–7 knots) that can only travel in decent seas—this complicates the logistics of
anything in the 30+ km range. Because of depth requirements, these are the most
likely areas for a cage project requiring tons of feed every day so faster crew boats
would be required weekly to transfer the feed to a lift boat on a continual basis. In
addition, once an operation is established with multiple cages and a substantial
investment in fish stock, there can be no interruptions due to lift boat vessel
maintenance, annual US Coast Guard inspections, and other mechanical issues.
Because of this need for continual operation a second, backup ASV would be
required for any large scale project that is conducted in GoM offshore waters.
Assuming the cage site is in the preferred 30–50 m water depth, the cost of lift
boats that can operate at these locations would be in the $5–20 + million dollars per
boat range and would require the expense of two rotating teams of crew members as
13 Offshore Platforms and Mariculture in the US
387