Offshore aquaculture, also known as open ocean
aquaculture, is an emerging approach to mariculture
or marine farming where fish farms are moved
some distance offshore.
The farms are positioned in deeper and less
sheltered waters, where ocean currents are
stronger than they are inshore.
Existing ‘offshore’ developments fall
mainly into the category of exposed areas
rather than fully offshore.
As maritime classification society, DNV GL,
has stated, development and knowledge-building
are needed in several fields for the available
deeper water opportunities to be realized.One
of the concerns with inshore aquaculture is
that discarded nutrients and feces can settle
below the farm on the seafloor and damage
the benthic ecosystem.
According to its proponents, the wastes from
aquaculture that has been moved offshore tend
to be swept away from the site and diluted.
Moving aquaculture offshore also provides
more space where aquaculture production can
expand to meet the increasing demands for
fish.
It avoids many of the conflicts that occur
with other marine resource users in the more
crowded inshore waters, though there can still
be user conflicts offshore.
Critics are concerned about issues such as
the ongoing consequences of using antibiotics
and other drugs and the possibilities of cultured
fish escaping and spreading disease among
wild fish.
== Background ==
Aquaculture is the most rapidly expanding
food industry in the world as a result of
declining wild fisheries stocks and profitable
business.
In 2008, aquaculture provided 45.7% of the
fish produced globally for human consumption;
increasing at a mean rate of 6.6% a year since
1970.In 1970, a National Oceanic and Atmospheric
Administration (NOAA) grant brought together
a group of oceanographers, engineers and marine
biologists to explore whether offshore aquaculture,
which was then considered a futuristic activity,
was feasible.
In the United States, the future of offshore
aquaculture technology within federal waters
has become much talked-about.
As many commercial operations show, it is
now technically possible to culture finfish,
shellfish, and seaweeds using offshore aquaculture
technology.Major challenges for the offshore
aquaculture industry involve designing and
deploying cages that can withstand storms,
dealing with the logistics of working many
kilometers from land, and finding species
that are sufficiently profitable to cover
the costs of rearing fish in exposed offshore
areas.
== Technology ==
To withstand the high energy offshore environment,
farms must be built to be more robust than
those inshore.
However, the design of the offshore technology
is developing rapidly, aimed at reducing cost
and maintenance.While the ranching systems
currently used for tuna use open net cages
at the surface of the sea (as is done also
in salmon farming), the offshore technology
usually uses submersible cages.
These large rigid cages – each one able
to hold many thousands of fish – are anchored
on the sea floor, but can move up and down
the water column.
They are attached to buoys on the surface
which frequently contain a mechanism for feeding
and storage for equipment.
Similar technology is being used in waters
near the Bahamas, China, the Philippines,
Portugal, Puerto Rico, and Spain.
By submerging cages or shellfish culture systems,
wave effects are minimized and interference
with boating and shipping is reduced.
Offshore farms can be made more efficient
and safer if remote control is used, and technologies
such as an 18-tonne buoy that feeds and monitors
fish automatically over long periods are being
developed.
=== Existing offshore structures ===
Multi-functional use of offshore waters can
lead to more sustainable aquaculture "in areas
that can be simultaneously used for other
activities such as energy production".
Operations for finfish and shellfish are being
developed.
For example, the Hubb-Sea World Research Institutes’
project to convert a retired oil platform
10 nm off the southern California coast to
an experimental offshore aquaculture facility.
The institute plans to grow mussels and red
abalone on the actual platform, as well as
white seabass, striped bass, bluefin tuna,
California halibut and California yellowtail
in floating cages.
=== Integrated multi-trophic aquaculture ===
Integrated multi-trophic aquaculture (IMTA),
or polyculture, occurs when species which
must be fed, such as finfish, are cultured
alongside species which can feed on dissolved
nutrients, such as seaweeds, or organic wastes,
such as suspension feeders and deposit feeders.
This sustainable method could solve several
problems with offshore aquaculture.
The method is being pioneered in Spain, Canada,
and elsewhere.
=== Roaming cages ===
Roaming cages have been envisioned as the
"next generation technology" for offshore
aquaculture.
These are large mobile cages powered by thrusters
and able to take advantage of ocean currents.
One idea is that juvenile tuna, starting out
in mobile cages in Mexico, could reach Japan
after a few months, matured and ready for
the market.
However, implementing such ideas will have
regulatory and legal implications.
== Space conflicts ==
As oceans industrialise, conflicts are increasing
among the users of marine space.
This competition for marine space is developing
in a context where natural resources can be
seen as publicly owned.
There can be conflict with the tourism industry,
recreational fishers, wild harvest fisheries
and the siting of marine renewable energy
installations.
The problems can be aggravated by the remoteness
of many marine areas, and difficulties with
monitoring and enforcement.
On the other hand, remote sites can be chosen
that avoid conflicts with other users, and
allow large scale operations with resulting
economies of scale.
Offshore systems can provide alternatives
for countries with few suitable inshore sites,
like Spain.
== Ecological impacts ==
The ecological impacts of offshore aquaculture
are somewhat uncertain because it is still
largely in the research stage.
Many of the concerns over potential offshore
aquaculture impacts are paralleled by similar,
well established concerns over inshore aquaculture
practices.
=== Pollution ===
One of the concerns with inshore farms is
that discarded nutrients and feces can settle
on the seafloor and disturb the benthos.
The "dilution of nutrients" that occurs in
deeper water is a strong reason to move coastal
aquaculture offshore into the open ocean.
How much nutrient pollution and damage to
the seafloor occurs depends on the feed conversion
efficiency of the species, the flushing rate
and the size of the operation.
However, dissolved and particulate nutrients
are still released to the environment.
Future offshore farms will probably be much
larger than inshore farms today, and will
therefore generate more waste.
The point at which the capacity of offshore
ecosystems to assimilate waste from offshore
aquaculture operations will be exceeded is
yet to be defined.
=== Wild caught feed ===
As with the inshore aquaculture of carnivorous
fish, a large proportion of the feed comes
from wild forage fish.
Except for a few countries, offshore aquaculture
has focused predominantly on high value carnivorous
fish.
If the industry attempts to expand with this
focus then the supply of these wild fish will
become ecologically unsustainable.
=== Fish escapes ===
The expense of offshore systems means it is
important to avoid fish escapes.
However, it is likely there will be escapes
as the offshore industry expands.
This could have significant consequences for
native species, even if the farmed fish are
inside their native range.
Submersible cages are fully closed and therefore
escapes can only occur through damage to the
structure.
Offshore cages must withstand the high energy
of the environment and attacks by predators
such as sharks.
The outer netting is made of Spectra – a
super-strong polyethylene fibre – wrapped
tightly around the frame, leaving no slack
for predators to grip.
However, the fertilised eggs of cod are able
to pass through the cage mesh in ocean enclosures.
=== Disease ===
Compared to inshore aquaculture, disease problems
currently appear to be much reduced when farming
offshore.
For example, parasitic infections that occur
in mussels cultured offshore are much smaller
than those cultured inshore.
However, new species are now being farmed
offshore although little is known about their
ecology and epidemiology.
The implications of transmitting pathogens
between such farmed species and wild species
"remains a large and unanswered question".Spreading
of pathogens between fish stocks is a major
issue in disease control.
Static offshore cages may help minimize direct
spreading, as there may be greater distances
between aquaculture production areas.
However, development of roaming cage technology
could bring about new issues with disease
transfer and spread.
The high level of carnivorous aquaculture
production results in an increased demand
for live aquatic animals for production and
breeding purposes such as bait, broodstock
and milt.
This can result in spread of disease across
species barriers.
== Employment ==
Aquaculture is encouraged by many governments
as a way to generate jobs and income, particularly
when wild fisheries have been run down.
However, this may not apply to offshore aquaculture.
Offshore aquaculture entails high equipment
and supply costs, and therefore will be under
severe pressure to lower labor costs through
automated production technologies.
Employment is likely to expand more at processing
facilities than grow-out industries as offshore
aquaculture develops.
== Prospects ==
Norway and the United States are currently
(2008) making the main investments in the
design of offshore cages.
=== FAO ===
In 2010, the Food and Agriculture Organization
(FAO) sub-committee on aquaculture made the
following assessments:
"Most Members thought it inevitable that aquaculture
will move further offshore if the world is
to meet its growing demand for seafood and
urged the development of appropriate technologies
for its expansion and assistance to developing
countries in accessing them [...] Some Members
noted that aquaculture may also develop offshore
in large inland water bodies and discussion
should extend to inland waters as well [...] Some
Members suggested caution regarding potential
negative impacts when developing offshore
aquaculture.The sub-committee recommended
the FAO "should work towards clarifying the
technical and legal terminology related to
offshore aquaculture in order to avoid confusion."
=== Europe ===
In 2002, the European Commission issued the
following policy statement on aquaculture:
"Fish cages should be moved further from the
coast, and more research and development of
offshore cage technology must be promoted
to this end.
Experience from outside the aquaculture sector,
e.g. with oil platforms, may well feed into
the aquaculture equipment sector, allowing
for savings in the development costs of technologies."By
2008, European offshore systems were operating
in Norway, Ireland, Italy, Spain, Greece,
Cyprus, Malta, Croatia, Portugal and Libya.In
Ireland, as part of their National Development
Plan, it is envisioned that over the period
2007–2013, technology associated with offshore
aquaculture systems will be developed, including:
"sensor systems for feeding, biomass and health
monitoring, feed control, telemetry and communications
[and] cage design, materials, structural testing
and modelling."
=== 
United States ===
Moving aquaculture offshore into the exclusive
economic zone (EEZ) can cause complications
with regulations.
In the United States, regulatory control of
the coastal states generally extends to 3
nm, while federal waters (or EEZ) extend to
200 nm offshore.
Therefore, offshore aquaculture can be sited
outside the reach of state law but within
federal jurisdiction.
As of 2010, "all commercial aquaculture facilities
have been sited in nearshore waters under
state or territorial jurisdiction."
However, "unclear regulatory processes" and
"technical uncertainties related to working
in offshore areas" have hindered progress.
The five offshore research projects and commercial
operations in the US – in New Hampshire,
Puerto Rico, Hawaii and California – are
all in federal waters.
In June 2011, the National Sustainable Offshore
Aquaculture Act of 2011 was introduced to
the House of Representatives "to establish
a regulatory system and research program for
sustainable offshore aquaculture in the United
States exclusive economic zone".
== Current species ==
By 2005, offshore aquaculture was present
in 25 countries, both as experimental and
commercial farms.
Market demand means that the most offshore
farming efforts are directed towards raising
finfish.
Two commercial operations in the US, and a
third in the Bahamas are using submersible
cages to raise high-value carnivorous finfish,
such as moi, cobia, and mutton snapper.
Submersible cages are also being used in experimental
systems for halibut, haddock, cod, and summer
flounder in New Hampshire waters, and for
amberjack, red drum, snapper, pompano, and
cobia in the Gulf of Mexico.The offshore aquaculture
of shellfish grown in suspended culture systems,
like scallops and mussels, is gaining ground.
Suspended culture systems include methods
where the shellfish are grown on a tethered
rope or suspended from a floating raft in
net containers.
Mussels in particular can survive the high
physical stress levels which occur in the
volatile environments that occur in offshore
waters.
Finfish species must be feed regularly, but
shellfish do not, which can reduce costs.
The University of New Hampshire in the US
has conducted research on the farming of blue
mussels submerged in an open ocean environment.
They have found that when farmed in less polluted
waters offshore, the mussels develop more
flesh with lighter shells.
== Global status ==
Status: E = Experimental, C = Commercial
== Notes ==
== Further references ==
James.
M.A. and Slaski, R. (2006) Appraisal of the
opportunity for offshore aquaculture in UK
waters.
Report of Project FC0934, commissioned by
Defra and Seafish from FRM Ltd., 119 pp [1]
Lee C and O’Bryenn PJ (Eds.) (2007) Open
Ocean Aquaculture—Moving Forward Oceanic
Institute workshop, Hawaii Pacific University.
Nolan, Jean T (2009) Offshore Marine Aquaculture
Nova Science.
ISBN 978-1-60692-117-3.
Aquaculture in the United States NOAA.
Updated 18 July 2011.
Stickney RR, Costa-Pierce B, Baltz DM, Drawbridge
M, Grimes C, Phillips S and Swann DL (2006)
Toward Sustainable Open Ocean Aquaculture
in the United States Fisheries, 31 (12): 607–610.
Offshore Aquaculture NOAA.
Updated 22 October 2007.
The National Offshore Aquaculture Act of 2007
NOAA.
Updated 5 September 2008.
Government Accountability Office Report on
Offshore Aquaculture NOAA.
Updated 18 June 2008.
Mittal, Anu K. (2008) Offshore Marine Aquaculture:
Multiple Administrative and Environmental
Issues Need to be Addressed in Establishing
a U.S. Regulatory Framework Diane Publishing.
ISBN 978-1-4379-0567-0.
Obama admin hands offshore aquaculture oversight
to NOAA New York Times, 23 April 2009.
Kapetsky JD and Aguilar-Manjarrez J (2007)
Estimating open ocean aquaculture potential
in EEZ with remote sensing and GIS: a reconnaissance
In: Geographic information systems, remote
sensing and mapping for the development and
management of marine aquaculture, FAO fisheries
technical paper 458.
ISBN 978-92-5-105646-2.
Watson, L and Drumm A (2007) Offshore Aquaculture
Development in Ireland, next steps FAO fisheries
technical report.
James, Mark and Slaski, Richard (2007) Appraisal
of the opportunity for offshore aquaculture
in UK water CEFAS Finfish News, Issue 3.
Offshore Aquaculture: The Next Wave for Fish
Farming?
World Wildlife Fund.
Retrieved 16 October 2011.
Offshore aquaculture viewpoints PBS.
Retrieved 16 October 2011.
Open ocean aquaculture can be destructive
Star Advertiser, 28 November 2010.
Ocean of trouble: Report warns of offshore
fish farming dangers Grist, 12 October 2011.
