Shrimps with salad, shrimps with pasta, shrimps with pizza, potted
shrimps with toast — if this delicacy has now become fairly common we
have the shrimp farmers in Europe, South America and particularly Asia
to thank. In the future thanks will also be due to satellites and the
important remote sensing data that they provide on aquaculture.

Shrimp farming is a thriving business. According to the Food and
Agriculture Organization (FAO) aquaculture production has increased
rapidly in the past decade while seafood production has remained
relatively stable – and shrimp farming is one of the fastest growing
sectors of the aquaculture industry.

Although shrimp farms can be found all over the world, the main cultured
shrimp-producing countries are in Latin America and Asia, and the main
markets are the United States, Japan and Europe. In value terms, shrimps
are the most important seafood product traded internationally.

As often happens, however, its rapid development has been accompanied by
controversial debates over the environmental, social and economic impact
of shrimp farming. Often, government planning and regulatory frameworks
have been unable to keep pace with the rapid rise in shrimp farms. Care
is needed to ensure that private returns on shrimp culture can be
sustained and to preserve the local environments of mangroves, creeks
and lagoons; coastal water quality; and wild shrimp stocks. This is
where ESA and the remote sensing data supplied by its satellites can
help out.

A few years ago ESA, FAO and the Government of Sri Lanka worked together
on a remote sensing study to protect and improve shrimp farming.
Outbreaks of disease had badly hit the shrimp farmers and one of the
causes was thought to be the uncontrolled proliferation of the farms,
which had damaged the environment. What was needed was precise regular
mapping of the shrimp farms to register their increase and growth, and
to monitor encroachment onto reservation areas.

ESA’s Earth Remote Sensing satellites are continually orbiting around
the Earth allowing the equipment onboard to provide constant data, in
all weather, on our environment. One of these instruments is called a
synthetic aperture radar (SAR). This data covers an area of 100 km2
and collects information on the same place on Earth, normally at
regular intervals of every 35 days.

By comparing SAR data of the selected shrimp farming area in Sri Lanka
for the last few years, and then developing the methodology to identify
and quantify the surface area enclosed by shrimp farms, it was possible
to assess their growth and to monitor their development. Once the
satellite data had been interpreted, a random field survey was
undertaken to check the accuracy of the methodology.

The results were extremely encouraging as the data proved to be more
than 90% accurate. The satellite data showed that in three years the
area covered by shrimp farms had increased by more than 44%. The high
resolution of the SAR data made it possible to pinpoint the areas in
which the growth had been most rapid and the remote sensing results
showed that the growth had been much greater than estimates carried
out by traditional means had led the authorities to believe.

As this was the first time that SAR data had been used to inventory
and monitor shrimp farms the most demanding part of the study was to
develop the methodology to interpret the data. However, now that this
has been developed it is can easily be used in other areas.

A further advantage was that the survey found the cost of using
satellite data to be relatively modest in comparison to that of aerial
photography. The latter also has the drawback of being more difficult
to obtain and being unavailable in cloudy weather — a condition
common in tropical and subtropical areas.

Given the positive results of the Sri Lanka study carried out with
ESA’s help, FAO prepared a regional project for the inventory and
monitoring of coastal and inland aquaculture which it is hoped will
come into operation in 2002. India, Indonesia, Malaysia, the
Philippines, Thailand and Vietnam have all requested to take part
in this study. An important feature of the project will be to train
local personnel in the use of the methodology developed in Sri Lanka
so that they will be able to interpret the satellite data for

Carlo Travaglia of FAO’s Environment and Natural Resources Service
expects the number of shrimp farms, as well as other forms of
aquaculture, to continue to grow over the next two decades. "A large
percentage of global production comes from small producers living
in developing countries. Satellites and shrimps are a strange
combination but one that is contributing to increasing food security,
alleviating poverty and safeguarding our environment".

Related links


* Network of Aquaculture Centres in Asia and the Pacific


[Image 1:]
Market demand for shrimps continues to increase worldwide. Photo: AP

[Image 2:]
Young boys catching shrimps in Bangladesh. Photo: FAO

[Image 3:]
Map of shrimp farms in the Seguwantiyu test site made with the help of
SAR data. By 1999 all available land for shrimp farms had already been
used. Credit: FAO

[Image 4:]
Shrimps being left to dry on the roof of a fishing boat. Photo FAO