As mud banks along the southwest coast of India dwindle, several concerns and societal implications have been articulated regarding this unique oceanographic phenomenon

Kumar, P.K. Dinesh

Aquatic Commons

30
SAMUDRA REPORT NO. 75
Decades back, at the Smithsonian Air and Space Museum in Washington D.C, 
there used to be a regular show in 
wide screen on ‘Mud Banks of 
Kerala’—an awe-inspiring event 
which was given equal importance 
to the launch of a space mission or 
an expedition to the rain forests of 
the Amazon! Mud banks (locally 
called Chakara)  appear in the south 
Indian state of Kerala in the littoral 
zones of the Arabian Sea during 
the summer southwest monsoon 
and remain calm with exceptional 
biological production and represent a 
unique oceanographic phenomenon. 
They are tranquil marine areas 
hugging the coast, which develop 
during the roughest monsoon 
period. They have a special feature 
of dampening high waves due to the 
huge quantities of mud in suspension 
close to the bottom. 
The mud banks appear as an 
undisturbed sheet of water, when 
blustery conditions prevail along the 
outer periphery. Towards the end of 
a hot, humid summer season, every 
citizen in the region, perspiring and 
sweating, looks eagerly towards the 
sky for the onset of the monsoon 
rains. When strong winds and high 
waves make it impossible to go out 
into the sea, the entire fisherfolk 
pray for the appearance of mud 
banks. The southwest monsoon 
arrives in Kerala with all its fury by 
early June, with raging seas and 
heavy rainstorms.  This is the time 
when the mud banks intermittently 
appear as patches of calm and 
turbid seas with copious fish stocks. 
The news spreads like wildfire and 
immediately transforms the entire 
coastline to a festive mood. Makeshift 
townships emerge with gatherings 
of thousands and thousands of 
people, when numerous canoes and 
nets are transported over land to the 
adjacent beaches. 
The hub of life and bustle is 
unimaginable, with huge baskets 
lined up to be filled to the brim with 
shrimps and fishes, and hundreds 
of refrigerated trucks to carry them 
to different parts of the country. 
A single cast of net during these 
days can yield a bumper harvest 
of mackerel, prawns, sardines and 
other fish species. Seafood processors 
and exporters queue up to buy the 
bumper crop and cash in on the 
abundance, and the whole crop is 
purchased in auction onshore itself.
Thus, the mud banks of Kerala 
have provided bountiful living 
resources to the needy, and helped 
to enhance their livelihoods for 
centuries. The mud banks of Kerala 
differ from mud banks reported from 
other muddy coasts worldwide, as 
they do not form a regular relief-
forming feature. The huge abundance 
of the fishery makes the Kerala mud 
banks  iconic.
God’s own country
With a narrow strip of lush green 
land bounded on the east by high hills 
laced with rivers and on the west by 
the Arabian Sea, Kerala is hailed 
as ‘God’s own country’ by admiring 
tourists. Kerala lies along the 
southwest corner of the Indian 
MUD BANKS
India
Muddy Waters
As mud banks along the southwest coast of India dwindle, several concerns and societal 
implications have been articulated regarding this unique oceanographic phenomenon
This article is by P.K. Dinesh Kumar 
(dineshku@nio.org) is Chief Scientist at  
CSIR-National Institute of  Oceanography, 
Regional Centre, Kochi, Kerala, India
Mud banks (locally called Chakara) appear in the 
south  Indian state of Kerala in the littoral zones of the 
Arabian Sea during the summer southwest monsoon
JANUARY 2017
31
M U D  B A N K S
peninsula, between 8° 18’ and 
12° 48’ N and 74°52’ and 77° 22’ E. 
The coastline has been subjected to 
severe alterations over a geological 
timescale due to a variety of factors, 
including the changing weather 
and climate, particularly the Indian 
monsoon. The region receives about 
300 cm of annual rainfall, as the 
44 rivers and numerous creeks of 
Kerala remain connected with lakes, 
lagoons and channels. A major part 
of the rains flows through rivers 
and creeks to eventually reach the 
Arabian Sea. 
This particular extent of 
40,000 sq km of the continental 
shelf of Kerala is considered as the 
most productive zone in the Arabian 
Sea. Coastal upwelling enhances the 
biological activity, leading to high 
fish production in the region. Since 
time immemorial, fish and fisheries 
have played a crucial role in the 
economic growth of the country. 
Although Kerala has a coastline of 
only about one-tenth of the Indian 
coastline, the fish landing from the 
state has contributed more than one-
fourth of the country’s total marine 
fish production. The sustainable 
fish yield from the southwest coast 
is estimated to be between 0.8 - 1.2 
mn tonnes per year, of which only 
about half is currently exploited. 
The coastal and nearshore waters 
are most important as they sustain a 
large population of traditional 
fishermen. The sector provides the 
source of income for hundreds of 
thousands of active fishermen and 
others engaged in allied activities. 
Therefore, a decline in the fishery 
potential can be a major concern to 
the state and the coastal community. 
The situation is precarious now, 
following a dwindling trend in the 
total fish landings, surprisingly due 
to the reduction in the appearance 
of mud banks along the southwest 
coast of India.  
The mud banks and fishery are, 
in fact, interdependent, as when 
the former occurs, the latter should 
follow. To many residents, a good 
mud bank means a good fishery. 
Since the calmness of the sea and 
mud accumulation are not significant, 
all mud banks need not be productive. 
Therefore, the success or failure of 
mud banks is judged from the 
quantity of fish caught during the 
season. Studies have shown that the 
mud banks sustain a high fishery 
potential, since the pelagic fishes 
and prawns move from deeper 
waters to closer to shore during 
the southwest monsoon, following 
upwelling. 
The general tendency of fish 
being to swim against the prevailing 
current (which is southerly), it is 
possible that they move in shoals 
northward and some of the fish, on 
passing through the mud bank area, 
are easily caught by the numerous 
canoes operating in, and outside, the 
mud banks. If so, it is also possible 
that a shoal of a particular 
composition, after its passing, is 
followed by another of entirely 
different composition. It is, therefore, 
likely that the monsoon catches 
from the mud bank area are from the 
moving shoals as they are caught 
from this region because fishing is 
possible only from this region.
Another argument is that 
upwelling causes the development of 
hypoxia over the shelf, which creates 
stress on the fishes and prawns, as 
they move either shoreward or to 
deeper waters. Such a condition 
occurs throughout the coast where 
upwelling is intense. During this 
migration, these shoals may also cross 
the mud bank zones. 
P.K. DINESH KUMAR
Sheer monsoon fi shery magic! Mud banks are tranquil marine areas 
hugging the coast, which develop during the roughest monsoon period
32
SAMUDRA REPORT NO. 75
With the onset of the southwest 
monsoon, fishing activities come to a 
standstill, and operations are possible 
only at locations where calm zones 
prevail. The monsoon fishery enjoys 
legal protection from the government, 
which provides exclusive operational 
rights to traditional crafts and has 
banned large mechanized vessels 
from fishing during the season. 
During this time of idling and poverty, 
only the calm zones brought in by 
mud banks can support fishermen 
as centres of intense fishing activity. 
Almost the entire fish landings during 
the monsoon season take place at 
these mud bank sites. 
History tells us that the ships of 
Vasco da Gama anchored in the open 
sea off Kozhikode (erstwhile Calicut) 
from 20 May to 26 August during 
the southwest monsoon of 1498. 
It was probably due to the mud banks 
prevalent in those regions, where 
the calm sea enabled the navigators 
a safe anchorage. Consequently, the 
big vessels could remain in the sea, 
and canoes and small boats were used 
to reach the shore during the 
monsoon season.
Documented records on the mud 
banks of Kerala are available from 
the 1840s. At least a dozen mud banks 
were known to have existed in the 
region for several centuries. Of these, 
some were sited either at, or near 
to, the outlets of rivers and lagoons. 
From the shore, the mud banks can 
be easily distinguished as zones with 
total absence of waves, while high 
swells break outside their periphery. 
In recent times, over 20 locations 
along the coast are found to have 
developed  mud banks at some time 
or the other. Prominent mud banks 
documented  in the 1980s have 
now vanished, and the remaining 
reported great characteristic changes 
in appearance and sustenance. Since 
2010, mud banks have been isolated 
in appearance along the coast at only 
two or three locations, and concerns 
have been raised about the total 
disappearance.
Looking into the factors leading to 
the dwindling of the mud banks, we 
may have to consider the geographical 
features of the areas surrounding 
them (including the lagoons and 
rivers emptying into them) and the 
transformations that have taken place 
there.  There have been significant 
changes in the land-use pattern in 
the hinterlands. These changes have 
dramatically altered the fertility, soil 
erosion, groundwater resources and 
surface water flow. There are about 
15 built dams in the rivers of Kerala, 
where a large part of water is retained. 
The silt and clay brought from the 
catchment areas of these dams are 
completely settled inside the dams. 
Once, the entire watersheds and 
lagoons were spread from the south 
end to the north end of the state, to 
make the region a dense cover for 
mangroves. However, an explosive 
growth in the population and 
urbanization have adversely affected 
the ecological stability of mangroves. 
The formation of mud banks along 
the coast of Kerala and the seasonal 
windfall fishery associated with them 
are interesting. A phenomenon like this 
has not been reported from anywhere 
else. Therefore, the dwindling and 
the worst-case scenarios of the 
extinction risk associated with these 
very specialized ecosystems  in this 
part of the world raise serious societal 
concerns about the future of the 
lifeline of this region. Therefore, the 
issues associated with the dwindling 
of mud banks need to be pushed 
to the centre of debate to facilitate 
an ecosystem- based approach to 
fisheries management. Serious 
environmental management strategies 
should be initiated immediately by 
involving researchers, economists, 
community people, fisherfolk and 
policy-makers.                                             
eprints.cmfri.org.in/7309/1/315-
IJMS_1974.pdf
Mud Banks of Kerala: Their 
Formation and Characteristics
drs.nio.org/drs/handle/2264/4940
Mud Banks of Kerala: Mystery Yet 
to be Unrevealed
For more
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India: mud banks, muddy waters

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