Resource Information System - Gahirmatha

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Resource Information System - Gahirmatha
(RISGAM)
ICMAM-PD
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Contents
Programme
Nesting Habit
Development Team
Shifting of Nesting
Introduction
Shoreline changes
Hydrological parameters
Gahirmatha Coast
Marine Organisms
Marine Sanctuary
Mangrove
Geomorphology
Threats
Landuse/Land Cover
Suggestions
Marine Turtle
Conclusion
Seaturtle Rookeries
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Gahirmatha Coast - Orissa
Gahirmatha is a sandy coast, which extends
approximately to a stretch of about 35-40 km from
Maipura river mouth in the north to Hansua river
mouth in the south. The beach is more or less
flat with scattered sand dune of 2-3 m height.
The beach spreads to about 80 m above the high
tide line with a maximum spread up to 100 m. The
vegetation is scanty and represented by Ipomea
sp. and Spinifex sp. Wetland, backwater/brackishwa
ter regions are also characteristic features of
this coast.
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Gahirmatha Marine Sanctuary
The Gahirmatha Marine Sanctuary extending from
86o 45 57 to 87o 17 36 E long and 20o 17 32
to 20o 46 58 N lat covers an area of 1435 sq.
km which includes 1408 sq. km. of water body and
27 sq. km. of land mass (Reserve Forest,
Mangroves, Mud flats and Sand bar). The
notification declaring the Marine Sanctuary was
published in the Extraordinary Issue No.1268
dated 17th October 1997 of Orissa Gazette.
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Gahirmatha Marine Sanctuary
Core Zone Area of turtle breeding ground of the
sanctuary is 725 sq. km. This has an average
width of 11 km offshore from Ekkulanasi in the
North-East and an average length of 10 km from
Barunei muhana to Mahanadi muhana.
Buffer Zone Turtle nesting ground stretches over
an average length of 10 km where fishing is
restricted during the nesting season from
November to May.
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Geomorphology
The coast of Gahirmatha is a low laying sandy
area, drained by the river Baitarani, Brahmani,
Dhamra, Maipura, Bansgarh and Ranhansua with
commonly occurring tidal creeks and mudflats. A
number of sandy islands are found along this
coast. Presence of barrier ridge (Barrier island)
is an important feature of this area, which
protects the sandy islands from erosion.
Sandy Islands
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Land use/ Land cover
The land use/land cover could be classified into
mangroves (136 sq. km), sandy islands (12 sq.
km), open shrub (17 sq. km) and settlements (10
sq. km). Dense mangrove vegetation is found in
and around Gahirmatha coast. Cultivation is
entirely rainfall dependent. A small part of the
land is used for paddy cultivation.
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Marine turtles in Gahirmatha Coast
Of the five species of sea turtles known to occur
in the Indian coast, four species occur in the
coastal waters of Orissa - Gahirmatha. In order
of abundance these are Lepidochelys olivacea
(olive ridley), Eretmochelys imbricata(hawksbill),
Dermochelys coriacea (leather back) and Chelonia
mydas (green turtle).
Lepidochelys olivacea
Lepidochelys olivacea
Eretmochelys imbricata
Click on species
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Marine turtles in Gahirmatha Coast
Of the five species of sea turtles known to occur
in the Indian coast, four species occur in the
coastal waters of Orissa - Gahirmatha. In order
of abundance these are Lepidochelys olivacea
(olive ridley), Eretmochelys imbricata(hawksbill),
Dermochelys coriacea (leather back) and Chelonia
mydas (green turtle).
Eretmochelys imbricata
Lepidochelys olivacea
Eretmochelys imbricata
Click on species
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Marine turtles in Gahirmatha Coast
Of the five species of sea turtles known to occur
in the Indian coast, four species occur in the
coastal waters of Orissa - Gahirmatha. In order
of abundance these are Lepidochelys olivacea
(olive ridley), Eretmochelys imbricata(hawksbill),
Dermochelys coriacea (leather back) and Chelonia
mydas (green turtle).
Lepidochelys olivacea
Eretmochelys imbricates
Click on species
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Marine turtles in Gahirmatha Coast
Of the five species of sea turtles known to occur
in the Indian coast, four species occur in the
coastal waters of Orissa - Gahirmatha. In order
of abundance these are Lepidochelys olivacea
(olive ridley), Eretmochelys imbricata(hawksbill),
Dermochelys coriacea (leather back) and Chelonia
mydas (green turtle).
Chelonia mydas
Lepidochelys olivacea
Eretmochelys imbricata
Click on species
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Sea turtle rookeries in Orissa Coast
Olive ridley turtle (Lepidochelys olivacea) is
the most common species of sea turtle occurring
along the east coast of India. These turtles
migrate every winter to nest en-mass at three
major rookeries viz. Gahirmatha, Devi River,
Rushikulya River in this area.
GahirmathaRookery
Devi Rookery
Rushikulya Rookery
Click on individual rookery site.
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Gahirmatha Rookery
The Gahirmatha rookery extending approximately to
35-40 km long stretch of Orissa coastline, hosts
the largest known nesting concentration of olive
ridley turtles. About 0.2 to 0.7 million turtles
are estimated to be visiting the beach every year
for mass nesting.
Main
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Devi River Rookery
This rookery is located at the Devi river mouth
(Jatadhar Muhana to Kadera river mouth) in
Cuttack district, 100 km South of Gahirmatha.
About 0.05 to 0.1 million turtles visit this
region for mass nesting every year (December to
April).
Main
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Rushikulya River Rookery
This rookery is located near Rushikulya river,
300 km South of the Gahirmatha mass nesting
beach. It extends to a distance of 6 km from
Paruna Bandha village (1 km north of the
Rushikulya river mouth) to Kantiagada village.
About 0.02 to 0.2 million turtles are estimated
to be visiting this beach every year for mass
nesting.
Main
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Nesting of Olive Ridley Turtle (Lepidochelys
Olivacea)
Nesting Environment
Nesting Behaviour
Hatchlings
Mass Nesting
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Nesting Environment
The mass nesting occurred due to the availability
of suitable nesting environment like sandy beach,
more or less flat topography, presence of
wetland, backwater, brackishwater and mangrove
vegetation in Gahirmatha coast.
Nesting season is from December to the end of
April with a peak in the middle of March. Olive
ridley turtles appear to nest during night time.
Main
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Nesting Behaviour
Female turtles emerge at night to lay eggs. The
turtles make a body pit for about 15-20 cm and an
egg pit of 40 cm depth. The depth of egg pit is
equal to the length of the rear flipper. The time
taken to complete nesting and laying of olive
ridley turtles is about 1½ - 2 hours. The average
number of eggs per clutch was found to be 111
(range 60-186).
Nesting behaviour
Egg laying
After nesting
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Nesting Behaviour
Female turtles emerge at night to lay eggs. The
turtles make a body pit for about 15-20 cm and an
egg pit of 40 cm depth. The depth of egg pit is
equal to the length of the rear flipper. The time
taken to complete nesting and laying of olive
ridley turtles is about 1½ - 2 hours. The average
number of eggs per clutch was found to be 111
(range 60-186).
Nesting behaviour
Egg laying
After nesting
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Nesting behaviour
Egg laying
After nesting
Main
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Mass Nesting
During 1988, 1997 and 1998, only a few thousand
turtles visited the coast for nesting. However, a
record number of 0.7 million turtles visited the
Barrier Island presently called Ekakulanasi,
during 2000.
Table Chart
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Nesting Population
Year Nesting Population (Nos.) Source
1976 15000 Kar Bhaskar 1982
1978 200000 Kar Bhaskar 1982
1979 130000 Kar Bhaskar 1982
1983 200000 Silas et. al. 1983
1984 500000 Silas et. al. 1985
1985 287000 Silas et. al. 1985
1986 80000 The Samaja (Orissa Newspaper)
1987 600000 The Samaja (Orissa Newspaper)
1988 50000 The Samaja (Orissa Newspaper)
1990 258000 The Samaja (Orissa Newspaper)
1995 339500 The Samaja (Orissa Newspaper)
1996 200000 The Samaja (Orissa Newspaper)
1997 50000 Forest Dept. RRL Data
1998 50000 Forest Dept. RRL Data
1999 253000 Forest Dept. RRL Data
2000 700000 Forest Dept. RRL Data
Main
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Hatchlings
Hatch out
Hatchlings (Mass)
Entering the sea
The emergence of hatchlings commences about 58
days after egg laying. At the mass nesting site,
it was observed that about 6,000 hatchlings
emerged from 53 nests in a 100 m stretch. The
percentage of live hatchlings emerging from
natural nests varied from 51.4 to 95.2 with an
average of 74.5. The hatchlings entering the sea
get washed ashore during high tide and they
re-enter the sea with subsequent retreating waves.
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Hatchlings
Hatch out
Hatchlings (Mass)
Entering the sea
The emergence of hatchlings commences about 58
days after egg laying. At the mass nesting site,
it was observed that about 6,000 hatchlings
emerged from 53 nests in a 100 m stretch. The
percentage of live hatchlings emerging from
natural nests varied from 51.4 to 95.2 with an
average of 74.5. The hatchlings entering the sea
get washed ashore during high tide and they
re-enter the sea with subsequent retreating waves.
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Hatchlings
The emergence of hatchlings commences about 58
days after egg laying. At the mass nesting site,
it was observed that about 6,000 hatchlings
emerged from 53 nests in a 100 m stretch. The
percentage of live hatchlings emerging from
natural nests varied from 51.4 to 95.2 with an
average of 74.5. The hatchlings entering the sea
get washed ashore during high tide and they
re-enter the sea with subsequent retreating waves.
Main
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Shifting of Gahirmatha mass nesting site
During the last 20 years, there has been a
shifting of mass nesting site towards the north
Orissa Coast, owing to gradual change of beach
profiles in the Gahirmatha Coast. The newly
formed Island is called the Nasi Island where
mass nesting continued from 1990 onwards.
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Shoreline changes in Gahirmatha
IRS 1D LISS-III 1998
Toposheet (SOI) 1972
The beach erosion and accretion are regular
annual phenomena. In May 1989, a cyclonic storm
swept across the Gahirmatha coast and fragmented
the mass nesting beach. However, currently due to
the heavy erosion of this region, the width of
the beach is reduced. The shoreline change
appears to be the main causative factor for
shifting of nesting site of olive ridley turtles
in the Gahirmatha coast.
DATA
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Comparative data of beach width in Gahirmatha
coast
Name of the place 1972 1998
Satabhaya 375 m 198 m
Gahirmatha 405 m 101 m
Habalikhati 756 m 159 m
Ekakula 70 m 123 m
Barrier Island 4 sq. km 5 sq. km
An analysis of the data on the width of the beach
available for nesting in Gahirmatha Coast during
1972 vis-à-vis 1998, presented in the table
(based on Survey of India Toposheet - 1972 IRS
1D LISS III 1998), would reveal a decline in the
width at Satabhaya, Gahirmatha and Habalikhati.
However, in Ekakula and Ekakulanasi, an increase
in the area was evident. The changes in the beach
width due to erosion may be attributed as one of
the reasons for shifting of nesting site.
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Temperature
Temperature plays an important role in the
nesting behaviour and incubation of hatching
process of sea turtles. The average monthly air
temperature data (in o C) in Gahirmatha for 1995
and 1998 are given in the table.
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Rainfall
In the present study (1998) the minimum average
rainfall of 3.0 mm was observed in January and a
maximum average rainfall of 318 mm in September.
The average rainfall data (in mm) for 1995 and
1998 are given in table.
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Humidity
Humidity is important for inducing the nesting
activity and building of nests by the turtles. In
the present study, the humidity value was
observed to range from 64 to 87 during 1998 in
the Gahirmatha coast. The average monthly
humidity values (in ) recorded are given in the
table.
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Hydrological Parameters
Physico-chemical parameters were studied during
May 98, Nov. 98, and May 1999 in six locations
viz., Maipura river, Maipura estuary, Maipura
(seaside), Wheeler island, Dhamra river and
Ekakula (seaside) region of Gahirmatha coast.
Salinity
Nitrite
D O
Nitrate
SPM
Phosphate
Click on individual parameters for more details.
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Salinity
The overall salinity ranged from 12.5 to 33.37
ppt during 1998-99. Lower salinity values were
recorded during monsoon and post-monsoon period.
Seasonal and station-wise salinity values (in
ppt.) are given below.
Main
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Dissolved Oxygen
The Dissolved Oxygen (DO) is an indicator of
health of water quality. It ranged from 6.9 mg/l
to 12.9 mg/l at Wheeler Island (seaside).
Seasonal and station-wise DO values (in mg/l) are
given below.
Main
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Suspended Matter
Suspended matter varied from 4.80 mg/l at
seaside of Ekakula to 230.71 mg/l at Wheeler
Island. In summer, suspended solids are generally
higher when compared to other seasons. The Table
shows Suspended Matter in Gahirmatha coastal
waters during 1998-99.
Main
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Nitrite
Nitrite content in Gahirmatha coastal waters
varied from 0.08 ?mol/l (at Ekakula) to 12.9
?mol/l (at Maipura estuary), as detailed below.
Main
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Nitrate
Nitrate content in Maipura river varied from 0.10
?mol/l to 5.57 ?mol/l. It was higher in
river/estuarine zone as compared to neritic zone.
The details are given below.
Main
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Phosphate
Phosphate content in Gahirmatha coast varied from
0.33 ?mol/l (at Maipura-seaside) to 2.11 ?mol/l
(Dhamra river). The details are given below.
Main
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Distribution of marine organisms in Gahirmatha
coast during 1998-99
(No. of species)
In the present study (1998-99), 207 species of
marine organisms were recorded in the estuarine
and neritic zones of Gahirmatha coast.
DATA
Phytoplankton
Zooplankton
Benthos
Click on individual group.
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Marine Organisms recorded in Gahirmatha Coast
(1998-99)
Group No. of species
Phytoplankton
Bacillariophyceae Dinophyceae Chlorophycea Cyanophyceae Euglenozoa Prymnesiophycea Xanthophyceae 95 10 4 4 1 1 1
Zooplankton
Hydrozoa Polychaeta Crustacea Polyhymenophora Sagittoidea Tentaculata Thaliacea Gastropoda Appendicularia 2 2 19 2 3 1 1 1 1
Group No. of species
Benthos
Annelida Arthropoda Mollusca Pisces Turtle 15 5 8 26 4
Overall
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Phytoplankton
In the present study (1998-99), 116 species of
phytoplankton were recorded (95 species of
Bacillariophyceae, 10 species of Dinophyceae, 4
species each of Chlorophyceae, Cyanophyceae and
one species each of Euglenophyceae,
Prymneziophyceae and Xanthophyceae). The maximum
diversity of phytoplankton was recorded during
December 1998. The maximum density of
phytoplankton recorded was 75.000/m3 in Wheeler
Island and 71,600/m3 in Maipura River. The
density of phytoplankton was found to be higher
in the estuarine zone than in the neritic zone.
Euglenophyceae
Overall
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Zooplankton
In the present study (1998-99), 18 zooplankton
groups were identified in Gahirmatha coast.
Totally 32 species of zooplankton were recorded.
They are 19 species of crustacea, 3 species of
sagittoidea, two species each of polyhymenophora,
polychaeta, hydrozoa and one species each of
appendicularia, thaliacea and tentaculata. The
zooplankton density was found to be higher in the
estuarine zone compared to neritic zone. The
maximum number of species was observed in the
post monsoon. The density of zooplankton ranged
from 49 to 2904 numbers/m3.
Overall
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Benthos
In the present study (1998-99) totally 29 species
of benthic organisms were recorded (15 species of
annelida, 5 species of arthropoda, 8 species of
mollusca and one species of chordata). The
maximum number of benthic organisms was recorded
during post-monsoon period.
Overall
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Mangroves
Mangroves
In Orissa, the mangroves extend from Balasore
coast to Puri coast covering an area of 211 sq.
km., of which 161 sq. km. is in and around the
Gahirmatha coastal region. Around Dhamra mouth,
the mangroves exist in very dense patches. The
Bhitarkanika sanctuary, a part of the Gahirmatha
coast, is located between 20 420 8 N
latitude and 86 45 E 87 50 longitude
covering an area of 672 sq. km.
Species composition
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Mangrove species composition
14 species of mangroves are found in the
Gahirmatha coastal region. They are
Derris scandens Bruguiera gymnorrhiza Bruguiera
sexangula Bruguiera parviflora Bruguiera
cylindrica Ceriops decendra Ceriops tagal.
Avicennia alba Avicennia officinalis Avicennia
marina Lumnitzera racemosa Exoecaria
agallocha Xylocarpus granatum X. mokongensi
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Major Threats
Indiscriminate fishing by trawlers in nearshore
and offshore coastal waters, without TED.
The females of the second arribada dig up pits in
the same stretches of the beach especially in the
core area which overlap with the first mass
nesting severely damaging the earlier nests as
well as the hatchlings.
Beach erosion, damage by predators, human
interference and change in the land use pattern
of coastal areas.
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Major Threats
Indiscriminate fishing by trawlers in nearshore
and offshore coastal waters, without TED.
The females of the second arribada dig up pits in
the same stretches of the beach especially in the
core area which overlap with the first mass
nesting severely damaging the earlier nests as
well as the hatchlings.
Beach erosion, damage by predators, human
interference and change in the land use pattern
of coastal areas.
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Major Threats
Indiscriminate fishing by trawlers in nearshore
and offshore coastal waters, without TED.
The females of the second arribada dig up pits in
the same stretches of the beach especially in the
core area which overlap with the first mass
nesting severely damaging the earlier nests as
well as the hatchlings.
Beach erosion, damage by predators, human
interference and change in the land use pattern
of coastal areas.
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Turtles as Incidental catches
Year No. of dead turtles recorded
1990-91 2,810
1991-92 2,315
1993-94 5,282
1994-95 3,250
1997-98 13,575
1998-99 30,000
1999-2000 20,000
(Source Kar and Dash 1990, Silas et. al 1984-85,
Pandav et. al 1994, Pandav and Choudhury 1999
and Das 2001.)
Decayed adult specimens and young ones were found
along the Gahirmatha beach during the nesting
season. This could be a part of incidental catch
from fishing gears operated from mechanised and
other fishing craft.
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Suggestion for turtle conservation

• Strict enforcement of Orissa Marine Fishing
  Regulation Act 1982 and Rules 1983, which
  prohibit any kind of mechanised fishing within 5
  km of the shore along Orissa coast for reducing
  the mortality of sea turtles.
• Use of Turtle Excluder Devices (TED) in the 3000
  trawlers operating off Orissa coast to minimize
  turtle mortality.
• Protection of nesting grounds and aquatic
  habitats by minimising human intervention/interfer
  ence in the nesting area.
• Creation of facilities for nesting, incubation,
  hatching and protection of the hatchlings along
  the beach.
• National and international coordination of
  conservation strategies.
• Creation of awareness among local people on
  conservation of turtles and its nesting grounds,
  through informal education, training, extension
  and media.
• Carrying out studies on the causative factors
  responsible for change in beach profile, which
  lead to shifting of nesting grounds and for
  planning corrective measures.

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Conclusion
The Information System developed for Gahirmatha
using remote sensing and GIS has demonstrated
that these tools could be effectively used for
monitoring and managing the breeding and nesting
grounds of olive ridley turtles in Gahirmatha
coast and their conservation.
ICMAM-PD