The ocean represents the single largest ecosystem on Earth comprising 1.3 billion cubic km
of water and more than 90% of the living space for life on the planet; yet it is the most poorly
understood of all the Earth’s ecosystems.
This study by Professor Alex Rogers of Somerville College, Oxford and Professor Rashid
Sumaila of the University of British Columbia is the first to consider the exclusive services of
the high seas (areas beyond national jurisdiction and comprising >70% of the total ocean
volume) and to place an economic value on them.
The study estimates that high seas ecosystems are responsible for nearly half of the
biological productivity of the global ocean, far more than previously thought.
While recognising that the science of carbon sequestration in the high seas is still
evolving, the study estimates that nearly half a billion tonnes of carbon, the
equivalent of over 1.5 billion tonnes of carbon dioxide, are captured and stored
by life in the high seas annually.
The value of carbon storage by the living component of high seas ecosystems
ranges between US$74 billion and US$222 billion annually (based on current
estimates of the economic cost of additional carbon in the atmosphere).
Out of about 47 billion tonnes of carbon fixed by phytoplankton, the study
estimates that the high seas are responsible for 49%, approx 23 billion tonnes.
Nearly 10 million tonnes of fish are caught annually on the high seas, which, in
turn, generate more than US$16 billion in gross landed value per year.
The study concludes that given that less than 1% of global fish catch is taken solely
in the high seas, it could make economic, social, and ecological sense to close the
high seas to fishing as this would result in higher net economic benefits and yield
within EEZ’s and provide a conservation benefit by contributing to a more sustainable
and resilient ocean.
There is overwhelming, albeit incomplete, evidence that the economic value of high
seas ecosystems and their associated services are very large.
These ecosystems generate both market values and values that are not traded in the
market, but still contribute to human economic and social wellbeing.
High seas ecosystems are degraded by past and current usage and threatened by
future impacts as industrial uses of the high seas expand.
Better environmental management of the high seas has been hampered by a chronic
under-valuation of the economic benefits that will arise from healthier high seas
We do not understand the value of the high seas in economic, social or cultural terms.
Without this information we cannot make informed decisions about the relative value of
allowing overfishing vs the relative value of carbon sequestration, replenishment of coastal
fish stocks or oxygen production.
The industrialisation and overuse of the high seas jeopardises the natural wealth of
ecosystems there and the services they provide to people.
Mining for minerals and new sources of fossil fuels will likely increase the industrial use of
the high seas and will further damage its ecosystems.
The governance of the high seas is fragmented, with different international institutions
focusing on specific industrial activities, places, or even different parts of the ecosystem.
There is growing evidence that the ecosystem services provided by the high seas are of high
social and economic value. The evidence is also clear that poor management of human
activities has eroded the natural wealth and productivity of high seas ecosystems with
negative economic and social consequences for all of us.
The Study examines 15* important ecosystem services provided by the high seas. These fall
under the following categories:
Provisioning services (seafood; raw materials; genetic resources; medicinal
resources; ornamental resources)
Regulating services (air purification; climate regulation; waste control; biological
Habitat services (lifecycle maintenance; gene pool protection)
Cultural services (recreation and leisure; aesthetic information; information for
culture, art and design; information for cognitive development)
*See Table Appendix A
The challenge is that few high seas ecosystem services can be accurately valued due to a
lack of scientific information about the use of them, their quantity and nature and even how
and where they are produced.
For example the high seas support economically important organisms that swim, migrate or
drift well beyond the physical boundaries of the high seas. This makes it difficult to capture
the contribution of high seas ecosystems to the services that are produced in the high seas
but are enjoyed elsewhere – sometimes thousands of kilometres away.
Therefore, the study assesses the value of these services as far as this is possible and
places them in the context of the costs of improved governance and management of human
activities in the high seas with a particular focus on improved marine protection.
The study focuses on providing estimates of the economic value of two important, high seas
ecosystem services: carbon storage and fisheries.
Carbon Storage
The ocean has captured and stored more than half the carbon dioxide (CO2) produced by
the burning of fossil fuels and a third of the total produced by humankind. This has reduced
the rates of atmospheric CO2 and can slow changes in global temperature and other
consequences associated with climate change.
It occurs through both physical and biological processes. Physical processes include CO2
dissolving in the ocean and being carried into the deep ocean for hundreds to thousands of
years. Biological processes include the ‘fixation’ of carbon by photosynthesis in the surface
layers of the ocean by phytoplankton (which then dies and sinks or is consumed, keeping
the carbon fixed away from the atmosphere).
The study estimates that of the roughly 47 billion tonnes of carbon fixed by phytoplankton,
the high seas are responsible for 49%, i.e. about 23 billion tonnes. (Although coastal regions
are more densely productive, the high seas has a very large surface area and thus account
for a huge amount of biological productivity in total).
The amount of carbon captured and stored at depth can be estimated from measures of
fixed carbon (net primary production) and how it is consumed or decomposed by animals
and microorganisms as it sinks.
Using an estimate of the amount of carbon stored below 1,000 metres (0.276 billion tonnes
per year), adding carbon exported through other biological mechanisms (nitrification, the
carbonate pump and dissolved organic carbon) and accounting for a portion of the
continental slope outside EEZs, the study estimates a total figure for biological carbon
capture and storage in the high seas of 0.448 billion tonnes of carbon annually.
The estimates of carbon capture and storage in the high seas are preliminary and subject to
a great deal of uncertainty because the rate at which organic carbon is consumed as it sinks
and the role of animals in actively moving the carbon from the surface into deep water are
To account for this uncertainty in calculating the economic value of the service, the authors
used the figure of 1.644 billion tonnes CO2 per year (+/- 50%) as a basis for estimating the
economic value of keeping CO2 out of the atmosphere. Applying a social cost of carbon
figure to this, they were then able to derive a total social benefit of carbon capture and
storage by the high seas to a value of $148 (ranging between 74 and 222) billion a year.
The estimates do not account for the additional changes which excess CO2 can bring about
in seawater (acidification and temperature increase, both of which are detrimental to ocean
The study analyses the economic impacts of high seas fisheries with a focus on the degree
of ‘sharing’ and interaction between fish stocks on the high seas and within EEZs. It found
that 42% of the global, commercially important fish species analysed are caught both in the
high and coastal seas. Less than 1% are caught exclusively on the high seas. The highly
migratory and ‘straddling’ stocks, which occur in both the high seas and in EEZs, account for
67% of the total global catch and 72% of total landed value associated with global
commercial fisheries.
A total annual average of about 10 million tonnes of fish from highly migratory and straddling
stocks were caught in the high seas constituting just over 12% of the global annual average
marine fisheries catch of 80 million tonnes. The landed value of this catch is estimated at
about US$16 billion annually, 15% of the total global marine landed value of around US$109
billion. Tuna species account for the largest share of value and the second largest share of
total catch.
Poorly managed fisheries affect the economic value of the service as well as other aspects
of social welfare, including the support of sustainable livelihoods, food security and
distributional equity; the impacts may affect the supply of other ecosystem services (e.g.
carbon capture and storage).
Focusing on the large pelagic species for which there is good data, the study finds that the
10 leading high seas fishing nations together land 63% of the high seas catch and capture
70% of the landed values. In descending order these are:
South Korea
‘High seas only’ fishing plays a relatively small role in the economic value of global fisheries
but a potentially large ecological role in the ocean – supporting the large global fishery that
exists within EEZs and some small-scale and subsistence fishing, all the while playing a key
role in the global ocean ecosystem.
This paradox suggests that it could make economic, social and ecological sense for the high
seas to be completely closed to fishing.
A recent paper (White and Costello, 2014) published in the scientific journal PLOS Biology
predicts that closing the high seas completely to fishing would result in higher net economic
benefits, relative to the current situation. By protecting the natural capital of fish stocks in the
high seas, coastal nations would continue to benefit from the fisheries that depend on the
high seas but can be caught in EEZs.
If closing the high seas to commercial fishing results in more fish in the sea, it could also
yield a conservation benefit by contributing to a more sustainable and resilient ocean – not
only to overfishing but to other threats such as climate change and ocean acidification.
Provisioning Services
Given the physical nature of provisioning services, their supply will strongly depend on the
abundance and numbers of species of living organisms within high seas ecosystems and the
structure of the communities and food webs they form. For example, if the abundance of
phytoplankton declines, organisms higher in the food chain will also decline.
The delivery of provisioning services depends on healthy ecosystems that assure the
abundance of economically important species and on ecological functions and community
structures that maintain stable food webs.
Regulating Services
It has been widely recognised that the diversity of life, reflected in the ecological
characteristics of living organisms of the seabed and water column, plays a fundamental role
in the maintenance of regulating services. This is because a diversity of living organisms
helps to control essential processes such as sedimentation, nutrient and gas cycling, and
the formation of habitat.
Human pressures that disrupt these processes will, in turn, affect the supply of regulating
services. For example, phytoplankton contribute to the biological carbon pump. Events and
activities that alter the composition of phytoplankton communities are likely to affect the
climate regulation service provided by marine ecosystems.
Bacteria, phytoplankton and zooplankton have fundamental roles related to nutrient cycling
and the removal of polluting particles from the environment. Whenever the structure of these
living communities is altered, the provision of regulating services such as air purification and
waste treatment will also likely be altered.
One indication that the service of biological control has already been altered may be found in
the bloom of a particular species (e.g. jellyfish or algae). For example, it is thought that
overfishing is capable, in some circumstances, of altering ecosystem structures to the point
where biological controls cannot re-establish healthy food webs.
Habitat Services
The two habitat services likely to be important in the high seas, ‘Lifecycle Maintenance’ and
‘Gene Pool Protection’, are closely related to essential ecological processes.
Changes in any of the critical ecological characteristics can alter the ability of a habitat to
support life. Such disruptions include changes in reproductive patterns and the development
of juvenile migratory species. For example, declines in the productivity of a habitat used by
migratory animals for breeding or for protection of juveniles may force these species to travel
longer distances to find suitable alternative locations
Governance, Ecosystem Health and the Services that Benefit Humankind
Human activities drive changes in ecosystem health. Pollution, the transmission of invasive
species, and direct habitat destruction (in the case of seafloor extraction) are detrimental to
ecological health and ecosystem service values of the high seas. The effects of climate
change, especially increasing ocean temperatures, decreasing oxygen and acidification, all
have the potential to alter the health and value of ecosystems services.
Many human activities that occur in high seas areas have both positive and negative
economic consequences. Some financially profitable activities are arguably independent of
ecosystem health, e.g. shipping and mining of deep-seabed mineral resources. Such
activities may directly and indirectly damage marine life and ecosystems. Other types of
activities depend directly on ecosystem health, yet the poor management of these activities
results in damage. For instance, by reducing the productivity and resilience of fish stocks,
overfishing has a direct impact on the ability of the high seas to produce seafood. Other
impacts of fishing such as bycatch, and the destruction of ecosystems and physical
disturbance (e.g. generation of sediment plumes by bottom trawls), can reduce stocks of
other types of seafood, and affect lifecycle maintenance, biological control, genetic and
medicinal resources, and even climate regulation.
The governance of the high seas is highly fragmented and this fragmentation needs to be
taken into account when predicting the potential outcome of better high seas governance.
Indeed, reduced fragmentation may be a proposed reform.
The high seas support at least 15 major categories of ecosystem services that are known to
be important to human wellbeing. These ecosystem services have demonstrable economic
value. While few of them can be valued using current data, two – carbon capture and
storage and commercial fisheries – generate tens of billions of dollars of value to society
High seas marine ecosystem services are thought to generate far less value than could be
possible because of uncontrolled and poorly managed human activities that damage them.
Better high seas management could stem the decline in the value of high seas ecosystem
services, improve the resilience of high seas ecosystems, and even increase the overall
value of these ecosystems and the services they produce.
There is overwhelming, albeit incomplete, evidence that the economic value of high seas
ecosystems and their associated services is vast.
The full study and an Executive Summary are available on request.
For further information please contact:
Nick Steel, [email protected], tel: (+44)7830185072

the high seas and us - Global Ocean Commission