'elopment and
going 1984
•d relief
ilitical tension
minate these
ing to decision
grams.
ree regions of
ther damaged
ary and early
rop production
imbabwe, and
impacts were
ries all
receding year as
in March and
st half of the
ya, Rwanda, and
The first six
over 40 years
n, the Sahel
record heat and
led growth of
Affected
1, Mali, Burkina
rought in the
sses over an
es. For those
ction in crop
cost on local
250,000,000.
rbiting
ssments. Early
ery indicated
rkina, and
ore detailed
Sahel zone of
indices for
rthern Burkina,
r year. During
ared specific
ust cumulative
in Tigray,
Wollo,
ishing during
or coordinate
r vegetation
Sahel Africa
nts were
/s before crop
times were 30
s before price
food shortages,
shortage alerts
3, Niger, and
roducts included
Department
js climate
is.
1 THE MARINE
?s Center
> for coastal
Bay and the
'ine assessments
ike Bay
;ify the
i the adjacent
lysical
) which control
isapeake Bay and
ice the passive
icruitment of
jding menhaden,
depends on the amount of larvae transported from
the shelf into the Bay. AISC oceanographers are
combining numerical models of wind induced mass
transport, fishery recruitment and remote sensing
technologies to derive relationships between the
physical environment and living marine resources.
The direct measurement of fisheries resources from
meteorological satellite data is not presently
feasible. However, satellite derived information
on sea-surface temperatures, waves, ocean fronts,
currents, chlorophyll, and sedimentation, is useful
in understanding the spatial and temporal impacts
of the physical environment on living and marine
resources.
AISC's assessments of the Chesapeake Bay also use
the National Weather Service's limited fine mesh
wind model to derive Ekman surface transport
values. The tremendous impact of urbanization and
thus sediment loadings on the Delaware and
Chesapeake Bays has significantly damaged fishery
resources. N0AA meteorological and Landsat imagery
increases AISC's capabilities in monitoring the
estuarine environment of the Chesapeake Bay.
Remotely sensed observations of surface sediment
and temperature plumes are providing insights into
land use, climate and fishery interactions. During
1985, AISC plans to correlate satellite imagery
with the Chesapeake Bay circulation model as well
as current and tide data. This could provide
ground-truth verification of the satellite
assessments.
POTENTIAL SATELLITE ASSESSMENTS FOR FISHERIES
RESOURCES IN THE PHILIPPINES
The Center is also using satellite imagery for
fisheries research in the Philippines. It is hoped
that through demonstrated satellite techniques in
the United States, scientists can provide an
operational assessment methodology to address
fisheries and habitat concerns in developing
countries.
The Philippines, like most Southeast Asian nations,
is strongly dependent on its fishery resources for
food and economic growth. Adoption of a 200-mile
Exclusive Economic Zone (EEZ) in 1978 coupled with
continuing government-sponsored fishery management
has enhanced the growth of the tuna industry. In
1981, it ranked twelfth in the world in total
fishery harvest. From an economic standpoint,
approximately 10 percent of the national population
of the Philippines is financially dependent on the
fishing industry. In the marine area, the
multi-species tuna fishery has received the
greatest attention because of the economic value of
the fishery, especially as an export item to the
world market. Tuna is the single most important
fishery export for the Philippines. Despite the
need for stringent management of tuna, this
resource is facing significant constraints. Two
significant problems emerge: (1) harvesting of
reproductively immature juveniles, and (2)
overexploitation of tuna stocks in the areally
limited traditional fishing grounds. Juvenile fish
have been estimated to comprise as much as 50
percent of the total annual tuna harvest.
The highly productive traditional fishing grounds
comprise less than 10 percent of the total marine
waters encompassed by the EEZ. However, they
account for almost 100 percent of the total
harvest. The impact of this concentrated fishing
pressure on the valuable Philippine tuna resource
is twofold: (1) depletion of stocks in the
traditional fishing areas, and (2) decreased
recruitment to the fishery. Realization of the
full potential of the resource requires
implementation of a sound tuna fishery management
plan which will protect juvenile fish and spawning
grounds, and ease fishing pressure by directing the
commercial fleet to productive fishing grounds in
the offshore waters of the EEZ. This latter aspect
would have the added benefit of lessening the
competition between commercial and municipal
fishermen.
AISC's current work in the Philippines is focused on
collecting baseline oceanographic data in combination
with satellite imagery to develop a tuna fisheries
assessment. The lack of recent synoptic ocean data
for the Philippines has required scientists to use
AVHRR satellite data to develop a data set of
"normals" and to determine the frequency of anomalous
events in local ocean circulation. This information
will be combined with (1) traditional oceanographic
data, (2) monthly harvests including yields and size
composition, (3) tuna migration routes and
periodicity along the eastern rim and archipelagic
waters of the Philippines, and (4) the economic growth
of the tuna fishing industry.
AVHRR data constitutes a very useful tool for a
general study of the marine resources in the
developing world. Such information is particularly
useful for analysing thermal and turbidity fronts.
The satellite thermal channels are used in the
generation of multi-channel sea surface temperature
(SST) images. The processed SST image is then color
contoured at one degree Centigrade intervals. This
easily allows scientists to determine the location of
thermal fronts for fisheries assessments. When the
full annual range of temperature for this area is
determined, scientists will develop a standardized
temperature scale for easier cross-scene comparison.
Channels 4 and 5 of N0AA 7 polar orbiter GAC data
were processed in generating this SST daytime image.
Temperatures are in 1 degree centigrade (C)
increments, except for temperatures greater than 27
degrees and less than 19 degrees C. The several blue
colored linear features south and west of the island
of Luzon are clouds which passed through a simplified
1 and/cloud masking technique but were detected by
their cold temperatures.
It is hoped that the SST images derived from
AVHRR/GAC data will allow the identification of
thermal fronts. Ecologists have documented the
tendency of foraging tuna to congregate along these
fronts. Bi-weekly assessments could greatly improve
the efficiency of the tuna fleet. Processors could
benefit by using the assessments to better plan their
work schedules and employment needs. The information
should also be useful in the development of flexible
and reasonable tuna management strategies. Timely
dissemination of this information will assist
government officials in setting allowable catch
quotas and assessing intra- and inter-annual
fluctuations in tuna production and yield.
Quantitative relationships that can be established
between fisheries distribution and oceanographic
variables will not only enhance future studies of
fish behavior and their responses to environmental
change but ultimately improve national fisheries
management practices. This is especially true for
fisheries that live in highly dynamic and complex
environments. AISC has shown that changes in the
physical environment can result in dramatic variation
in productivity and the resultant catch. State and
national management practices can be strengthened by
relating changes in stock size to environmental
changes and fishing pressure. The U.S. marine
assessments and the Philippine assessments attempt to
use AVHRR information for an operational marine
product.
CONCLUSIONS
From the above discussions, one realizes the
