(DRAFT) - Taxonomy
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
TAXONOMY
NAME - turtle, olive ridley
OTHER COMMON NAMES - olive ridley sea turtle, tortuga golfina, tortuga bestia, manila, mani, batali, Pacific ridley, warana, tortue, olivatre, xibirro, carpintera, penyu lipas, penyu rantau and penyu abu abu
ELEMENT CODE -
CATEGORY - Reptiles
PHYLUM AND SUBPHYLUM - Chordata,
CLASS AND SUBCLASS - Reptilia,
ORDER AND SUBORDER - Chelonia,
FAMILY AND SUBFAMILY - ,
GENUS AND SUBGENUS - Lepidochelys,
SPECIES AND SSP - olivacea,
SCIENTIFIC NAME - Lepidochelys olivacea
AUTHORITY -
TAXONOMY REFERENCES - 91
COMMENTS ON TAXONOMY -
In various parts of its range, the olive ridley sea turtle may also be
called tortuga golfina, tortuga bestia, manila, mani, batali, Pacific
ridley, warana, tortue olivatre, xibirro, carpintera, penyu lipas, penyu
rantau, and penyu abu abu *91*.
Taxonomy - 1 (DRAFT) - Status
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
STATUS
Coded Status
E: Federal Endangered
T: Federal Threatened
Threatened throughout range critically state endangere
Commercial/consumption
See Comments
REFERENCES FOR STATUS - 91 and 274
COMMENTS ON STATUS -
The local and commercial harvest of olive ridley populations for meat,
leather, and eggs is the primary cause of depletion. For example, this
species is the most economically important sea turtle in Mexico where legal
and illegal fisheries exist. In the five years prior to 1969, an estimated
2,000,000 olive ridleys were landed by the legitimate commercial fishery.
About 70,000 turtles were taken from La Escobilla in 1977, 58,000 in 1978,
and 24,500 in 1979. The main turtle processing plant in Mexico was
nationalized in 1981. Subsequently, the turtle quota set by the Mexican
government for the 1981/82 season was increased by 72% over the previous
season and allowed a take of 69,000 turtles. By December 1981, 56,000
turtles had been taken. The quota for the 1983/84 season was set at 50,000
turtles. Only 26,000 turtles were taken by December 1983, and an additional
2,000 were taken be the end of January 1984, suggesting a substantial
decline in availability. The legal commercial harvest in Mexico is
overshadowed by poaching; millions of eggs and thousands of animals are
taken illegally each year--an estimated one million eggs were poached at La
Escobilla in 1969 alone.
From 1970 to 1977, between 132,000 and 147,000 adults were harvested in
Ecuador for the international skin trade. From 1978 to 1981, the harvest
increased to between 290,000 and 320,000 adults as estimated from the weight
(approximately 1,273,000 pounds) of skin that were exported. Although
Ecaudor banned the export of turtle products in 1981, Japan imported from
Ecaudor 18,623 pounds of skin in 1981, 74,272 pounds in 1982, and 6,600
pounds through October 1983. While commercial exploitation has at least
slowed in Ecaudor, there are some indications that this activity has now
shifted to Colombia.
In India, olive ridley populations are being depleted primarily by illegal
harvest of eggs and turtles for food and by human colonization of many
nesting beaches. Apparently, thousands of turtles are taken yearly off the
coast of Orissa, one of the largest remaining breeding colonies of olive
ridleys in the world. This take is reportedly increasing. Also, more than
100,000 eggs were reportedly taken in 1982 at Gahirmatha alone and sold in
Calcutta.
In other areas where olive ridleys are found, such as Pakistan and Sri
Lanka, the take of turtles for human consumption is very large. Also,
hundreds of thousands of eggs are removed from Ostional Beach, Costa Rica
each year. The removal of virtually all of the olive ridley eggs at
Eilanti, Surinam, by the Carib Indians up until the late 1960's may have
caused the drastic decline there.
In the United States, the olive ridley is protected by the Endangered
Status - 1 (DRAFT) - Status
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
Species Act of 1973. It is listed as threatened throughout the world,
except the breeding colony populations on the Pacific coast of Mexico which
are endangered.
Some large imports, such as Japan, have taken reservations on this species
which means they will still import products from olive ridleys *91*.
Status - 2 (DRAFT) - Distribution
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine BB. V 1
Marine BB. V 1
Marine BB. V 1
REFERENCES FOR NWI - 91
COMMENTS ON HABITAT ASSOCIATIONS -
Preferred habitats are tropical bays and lagoons. Specific nesting times
vary with location. Nesting occurs year-round in Costa Rica, between June
and July in Surinam, into August in Pacific Mexico, and from September to
November in other areas of the east Pacific *91*.
Habitat Associations - 1 (DRAFT) - Food Habits
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
HERBIVORE/GRAZER
REFERENCES FOR TROPHIC LEVEL - 91
LIFESTAGE FOOD FOOD PART
General Plants Not Specified
General Crustaceans Not Specified
General Snails Not Specified
General Osteichthyes Egg/Fetus stage
General Molluscs Not Specified
General Scyphozoans Not Specified
General Sea/Heart Urchins Not Specified
REFERENCES FOR GENERAL FOOD - 91
REFERENCES FOR ADULT FOOD - 91
COMMENTS ON FOOD -
This turtle has been observed eating fish, crabs, snails, oysters,
jellyfish, sea urchins, fish eggs, and vegetation. Olive ridleys are
believed to be capable of feeding far offshore and forage at great depths
*91*.
COMMENTS ON ADULT FOOD -
This turtle has been observed eating fish, crabs, snails, oysters,
jellyfish, sea urchins, fish eggs, and vegetation. Olive ridleys are
believed to be capable of feeding far offshore and forage at great depths
*91*.
Food Habits - 1 (DRAFT) - Environment Associations
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Air Temperature: Specified in Comments
G Substrate: Sand
G Relation to Substrate: Unattached - normally free living
G Bottom Type [Aquatic]: Sand
G Aquatic Habitat Zonation: Specified in Comments
G Estuarine habitat zone: bay
G Wave intensity: specified in comments
LIM Substrate: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 91
REFERENCES FOR LIMITING ENVIRONMENTAL ASSOC_ - 91
REFERENCES FOR FEEDING ADULT ENVIRONMENTAL ASSOC_ - 91
REFERENCES FOR RESTING ADULT ENVIRONMENTAL ASSOC_ - 91
REFERENCES FOR BREEDING ADULT ENVIRONMENTAL ASSOC_ - 91
REFERENCES FOR RESTING JUVENILE ENVIRONMENTAL ASSOC_ - 91
REFERENCES FOR EGG ENVIRONMENTAL ASSOC_ - 91
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
HABITAT ZONE: Preferred habitats are tropical bays and lagoons.
TEMPERATURE AND WAVE ACTION: Natural forces that affect olive ridleys
include storms, temperature, rain, and wave surge. The effects of these
forces on the continued existence of this species are not known, but these
forces can create beach erosion or accretion, prevent turtles from nesting,
destroy eggs and hatchlings, and reduce nesting success.
SUBSTRATE: The build up of mud flats in front of olive ridley nesting
beaches may pose a threat to nesting populations *91*.
COMMENTS ON RESTING ADULT ENVIRONMENTAL ASSOC_ -
HABITAT ZONE: Preferred habitats are tropical bays and lagoons.
TEMPERATURE AND WAVE ACTION: Natural forces that affect olive ridleys
include storms, temperature, rain, and wave surge. The effects of these
forces on the continued existence of this species are not known, but these
forces can create beach erosion or accretion, prevent turtles from nesting,
Environment Associations - 1 (DRAFT) - Environment Associations
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
destroy eggs and hatchlings, and reduce nesting success.
SUBSTRATE: The build up of mud flats in front of olive ridley nesting
beaches may pose a threat to nesting populations *91*.
COMMENTS ON FEEDING ADULT ENVIRONTAL ASSOC_ -
HABITAT ZONE: Olive ridleys are believed to be capable of feeding far
offshore and forage at great depths *91*.
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
TEMPERATURE AND WAVE ACTION: Natural forces that affect olive ridleys
include storms, temperature, rain, and wave surge. The effects of these
forces on the continued existence of this species are not known, but these
forces can create beach erosion or accretion, prevent turtles from nesting,
destroy eggs and hatchlings, and reduce nesting success.
SUBSTRATE: The build up of mud flats in front of olive ridley nesting
beaches may pose a threat to nesting populations *91*.
COMMENTS ON RESTING JUVENILE ENVIRONMENTAL ASSOC_ -
TEMPERATURE AND WAVE ACTION: Natural forces that affect olive ridleys
include storms, temperature, rain, and wave surge. The effects of these
forces on the continued existence of this species are not known, but these
forces can create beach erosion or accretion, prevent turtles from nesting,
destroy eggs and hatchlings, and reduce nesting success.
SUBSTRATE: The build up of mud flats in front of olive ridley nesting
beaches may pose a threat to nesting populations *91*.
COMMENTS ON EGG ENVIRONMENTAL ASSOC_ -
TEMPERATURE AND WAVE ACTION: Natural forces that affect olive ridleys
include storms, temperature, rain, and wave surge. The effects of these
forces on the continued existence of this species are not known, but these
forces can create beach erosion or accretion, prevent turtles from nesting,
destroy eggs and hatchlings, and reduce nesting success.
SUBSTRATE: The build up of mud flats in front of olive ridley nesting
beaches may pose a threat to nesting populations *91*.
Environment Associations - 2 (DRAFT) - Life History
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
LIFE HISTORY
PHYSICAL DESCRIPTION: The olive ridley sea turtle resembles the Kemp's
ridley, but it has a thinner, more narrow shell and a smaller, more lightly
built skull. The upper shell is also generally higher than Kemp's ridley
and has greater variation in the number of plates (five to nine pairs).
Other characteristics are two pairs of prefrontal scales (scales found
between the nasal opening and the eye sockets); a pore near the rear of the
plates bordering the upper and lower shells; and shell plates that do not
overlap. The shell is heart-shaped to round and may be gray, brown, black,
or olive. The underside of the adults is usually yellow but is white in
immature turtles and gray to black in hatchlings.
As adults, the olive ridleys are the smallest of the sea turtles. They may
weigh as much as 100 lb with shells generally between 24 and 30 inches long.
Although subadult males and females look alike externally, the adult male's
tail extends some distance beyond the rear edge of the shell whereas the
adult female's tail is much shorter. Males also have one of two claws on
each forelimb enlarged and strongly curved *91*.
LONGEVITY AND MATURITY: Olive ridleys may be longlived in the wild, but
exact longevity is not known. At sexual maturity, which likely takes at
least 7 to 9 years in wild populations, the shell is usually about 24 to 25
inches long, and the turtle weighs about 80 lb.
FOOD HABITS: This species has been observed eating fish, crabs, snails,
oysters, jellyfish, sea urchins, fish eggs, and vegetation. Olive ridleys
are believed to be capable of feeding far offshore and forage at great
depths.
PREDATORS: Predators of adults are primarily man, sharks, and large cats
such as jaguars and cougars on particular beaches. Hatchlings and/or eggs
fall prey to man, crabs, birds, fish, and other mammals such as coyotes,
pigs, coatimundi, and feral dogs. Survivorship from eggs to adults is
probably very low.
REPRODUCTION: Nesting usually occurs in aggregations called arribadas
(meaning arrival) on mainland beaches during nights with strong winds.
Specific nesting times vary with location. For example, nesting occurs
year-round in Costa Rica, between June and July in Surinam, into August in
Pacific Mexico, and from September to November in other areas of the east
Pacific. Females usually nest in intervals ranging from 14 to 48 days,
depositing 2 to 3 (average 1.4 in Surinam) clutches of eggs. Mean clutch
size varies usually between 105 and 116 eggs which hatch in 50 to 70 days.
Most hatchlings emerge at night and little is known about the juvenile and
subadult phases of the life cycle since these stages have only rarely been
observed at sea. Most returning females nest annually, but remigrations
(return of females to nest in succeeding years) have been observed in 2, 4,
5, and 6-year intervals.
POPULATION SIZE: There is not enough information to allow separation of
olive ridleys into taxonomic subunits. However, geographically and
genetically different populations likely exist. Therefore, consideration of
this species as other than a single species is ill advised and for purposes
of this review, the species is considered a single population in the
Indo-Pacific region and eastern Atlantic, and a single population in the
western Atlantic.
The population levels of olive ridleys that existed before commercial
exploitation or the numbers that now exist are unknown. Insight can only be
Life History - 1 (DRAFT) - Life History
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
gained into the decline of these turtles based on the number of nesting
females (sex ratios have not yet been determined so the number of males
cannot be determined). Also, information is not available on the number of
hatchlings, juveniles, and subadults in the water. The decline in nesting
females and the low frequency of encounters with turtles in the wild
provides inferential evidence that populations are generally declining. For
example, of all known nesting locations, only in Australia (a minor nesting
location) is the population considered stable.
Where more complete information is available, especially in the major
nesting regions, alarming declines in the remaining olive ridley populations
are evident. Pacific Mexico supported an estimated 10 million adults before
1950; an estimated 1,185,000 adults (including 593,667 females) prior to
1969; and 485,000 adults in 1976. In the early 1970's, between 179,000 and
400,000 nesting females arrived at various beaches in Mexico. Only the
Oaxaca beaches (La Escobilla) still support large-scale nesting populations.
The breeding populations at other Mexican beaches have reportedly all but
disappeared. More recent population estimates for adult olive ridleys from
the Pacific coast of Mexico are 153,300 in 1981, 164,200 in 1982, and 79,900
in 1983.
The Surinam population of olive ridleys apparently has undergone a startling
decline in the number of nesting females over the years. The nesting
population estimated at 2,100 to 3,000 females in 1967-68 dropped to an
estimated 550-800 females in 1978 and 1979. Population estimates are 550
nesting females in in 1980, 600 in 1981, and only 400 in 1982. The survival
prospects for this population are poor, possibly because of killing of
turtles in shrimp trawls and an active market for skin in the leather trade.
Even with protection, the olive ridley population has dropped to low levels.
Also, physical changes in the nesting beaches may present a problem.
Erosion and deposition occur constantly. Presently, turtles must cross
extensive soft mud flats to reach the beach. These environmental changes
may inhibit future nesting of olive ridleys at Surinam.
Nesting populations at Nancite and Ostional, Costa Rica, were considered
fairly secure. However, the nesting population at Ostional has dropped
about 30 percent, probably due to egg poaching. The nesting population at
Nancite is plagued by extremely low egg survival. Between 15 and 30 percent
of the eggs deposited during one arribada may be destroyed by turtles
nesting later. Also, hatching success may be lower than one percent largely
due to actions of ghost crabs, dipterans, and infections by bacteria and
fungi.
Populations in India and Sri Lanka also may be declining. Although sea
turtles are protected there, poaching of eggs and adults is active,
especially at Orissa and West Bengal. All the sea turtle populations in
India and Sri Lanka are believed to be declining. Even though sea turtles
are protected, enforcement of laws protecting these animals is poor.
COMMENTS ON LIFE HISTORY -
LONGEVITY AND MATURITY: Olive ridleys may be longlived in the wild, but
exact longevity is not known. At sexual maturity, which likely takes at
least 7 to 9 years in wild populations, the shell is usually about 24 to 25
inches long, and the turtle weighs about 80 lb.
FOOD HABITS: This species has been observed eating fish, crabs, snails,
oysters, jellyfish, sea urchins, fish eggs, and vegetation. Olive ridleys
are believed to be capable of feeding far offshore and forage at great
Life History - 2 (DRAFT) - Life History
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
depths.
PREDATORS: Predators of adults are primarily man, sharks, and large cats
such as jaguars and cougars on particular beaches. Hatchlings and/or eggs
fall prey to man, crabs, birds, fish, and other mammals such as coyotes,
pigs, coatimundi, and feral dogs. Survivorship from eggs to adults is
probably very low.
REPRODUCTION: Nesting usually occurs in aggregations called arribadas
(meaning arrival) on mainland beaches during nights with strong winds.
Specific nesting times vary with location. For example, nesting occurs
year-round in Costa Rica, between June and July in Surinam, into August in
Pacific Mexico, and from September to November in other areas of the east
Pacific. Females usually nest in intervals ranging from 14 to 48 days,
depositing 2 to 3 (average 1.4 in Surinam) clutches of eggs. Mean clutch
size varies usually between 105 and 116 eggs which hatch in 50 to 70 days.
Most hatchlings emerge at night and little is known about the juvenile and
subadult phases of the life cycle since these stages have only rarely been
observed at sea. Most returning females nest annually, but remigrations
(return of females to nest in succeeding years) have been observed in 2, 4,
5, and 6-year intervals.
POPULATION SIZE: There is not enough information to allow separation of
olive ridleys into taxonomic subunits. However, geographically and
genetically different populations likely exist. Therefore, consideration of
this species as other than a single species is ill advised and for purposes
of this review, the species is considered a single population in the
Indo-Pacific region and eastern Atlantic, and a single population in the
western Atlantic.
The population levels of olive ridleys that existed before commercial
exploitation or the numbers that now exist are unknown. Insight can only be
gained into the decline of these turtles based on the number of nesting
females (sex ratios have not yet been determined so the number of males
cannot be determined). Also, information is not available on the number of
hatchlings, juveniles, and subadults in the water. The decline in nesting
females and the low frequency of encounters with turtles in the wild
provides inferential evidence that populations are generally declining. For
example, of all known nesting locations, only in Australia (a minor nesting
location) is the population considered stable.
Where more complete information is available, especially in the major
nesting regions, alarming declines in the remaining olive ridley populations
are evident. Pacific Mexico supported an estimated 10 million adults before
1950; an estimated 1,185,000 adults (including 593,667 females) prior to
1969; and 485,000 adults in 1976. In the early 1970's, between 179,000 and
400,000 nesting females arrived at various beaches in Mexico. Only the
Oaxaca beaches (La Escobilla) still support large-scale nesting populations.
The breeding populations at other Mexican beaches have reportedly all but
disappeared. More recent population estimates for adult olive ridleys from
the Pacific coast of Mexico are 153,300 in 1981, 164,200 in 1982, and 79,900
in 1983.
The Surinam population of olive ridleys apparently has undergone a startling
decline in the number of nesting females over the years. The nesting
population estimated at 2,100 to 3,000 females in 1967-68 dropped to an
estimated 550-800 females in 1978 and 1979. Population estimates are 550
nesting females in in 1980, 600 in 1981, and only 400 in 1982. The survival
prospects for this population are poor, possibly because of killing of
Life History - 3 (DRAFT) - Life History
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
turtles in shrimp trawls and an active market for skin in the leather trade.
Even with protection, the olive ridley population has dropped to low levels.
Also, physical changes in the nesting beaches may present a problem.
Erosion and deposition occur constantly. Presently, turtles must cross
extensive soft mud flats to reach the beach. These environmental changes
may inhibit future nesting of olive ridleys at Surinam.
Nesting populations at Nancite and Ostional, Costa Rica, were considered
fairly secure. However, the nesting population at Ostional has dropped
about 30 percent, probably due to egg poaching. The nesting population at
Nancite is plagued by extremely low egg survival. Between 15 and 30 percent
of the eggs deposited during one arribada may be destroyed by turtles
nesting later. Also, hatching success may be lower than one percent largely
due to actions of ghost crabs, dipterans, and infections by bacteria and
fungi.
Populations in India and Sri Lanka also may be declining. Although sea
turtles are protected there, poaching of eggs and adults is active,
especially at Orissa and West Bengal. All the sea turtle populations in
India and Sri Lanka are believed to be declining. Even though sea turtles
are protected, enforcement of laws protecting these animals is poor.
LISTING FACTORS: 1. The present or threatened destruction, modification,
or curtailment of its habitat or range.
A. Pollutants from industrial and residential development. These include
oil, herbicides, pesticides, radionuclides, PCBs, heavy metals, and sewage.
The effects of pollutants are difficult to detect and evaluate, except for
oil and tar balls that are known to have killed ridleys by fouling and/or
ingestion. The other contaminents may cause physiological problems, such as
reducing the reproduction success of this species.
B. Exploratory oil and gas drilling. These activities may affect ridleys
by attracting them to lighted platforms where they may be suscepible to
increased predation; by disrupting feeding habitat when disposing of
drilling mud and sediments; and by discharging oil which may contaminate
turtles and cause irritation or permanent damage to eyes, affect
respiration, or produce abnormal behavior.
C. Disposal of garbage at sea. Plastic and other foreign materials that
are ingested by turtles may cause death. Also, turtles may be fouled by
plastic which could adversely affect survival if the animals are unable to
shed the plastic. Additionally, turtles attracted to refuse may be
subjected to more predators such as sharks which may also be attracted to
the refuse.
D. Dredge and fill. These activities may affect habitat that turtles use,
or the equipment (e.g. dredge cutter head) may harm or kill turtles if
encountered during the dredging operation.
E. Power boats. Power boats can injure or kill sea turtles.
2. Overutilization for commercial, recreational, scientific, and
educational purposes.
The use of olive ridleys for scientific purposes, while unquantified, is
small and not a contributing factor in population declines. Research is
geared toward enhancing populations, and, therefore, benefits rather than
harms the species.
The local and commercial harvest of olive ridley populations for meat,
leather, and eggs is the primary cause of depletion. For example, this
species is the most economically important sea turtle in Mexico where legal
and illegal fisheries exist. In the five years prior to 1969, an estimated
Life History - 4 (DRAFT) - Life History
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
2,000,000 olive ridleys were landed by the legitimate commercial fishery.
About 70,000 turtles were taken from La Escobilla in 1977, 58,000 in 1978,
and 24,500 in 1979. The main turtle processing plant in Mexico was
nationalized in 1981. Subsequently, the turtle quota set by the Mexican
government for the 1981/82 season was increased by 72% over the previous
season and allowed a take of 69,000 turtles. By December 1981, 56,000
turtles had been taken. The quota for the 1983/84 season was set at 50,000
turtles. Only 26,000 turtles were taken by December 1983, and an additional
2,000 were taken be the end of January 1984, suggesting a substantial
decline in availability. The legal commercial harvest in Mexico is
overshadowed by poaching; millions of eggs and thousands of animals are
taken illegally each year--an estimated one million eggs were poached at La
Escobilla in 1969 alone.
From 1970 to 1977, between 132,000 and 147,000 adults were harvested in
Ecuador for the international skin trade. From 1978 to 1981, the harvest
increased to between 290,000 and 320,000 adults as estimated from the weight
(approximately 1,273,000 pounds) of skin that were exported. Although
Ecaudor banned the export of turtle products in 1981, Japan imported from
Ecaudor 18,623 pounds of skin in 1981, 74,272 pounds in 1982, and 6,600
pounds through October 1983. While commercial exploitation has at least
slowed in Ecaudor, there are some indications that this activity has now
shifted to Colombia.
In India, olive ridley populations are being depleted primarily by illegal
harvest of eggs and turtles for food and by human colonization of many
nesting beaches. Apparently, thousands of turtle are taken yearly off the
coast of Orissa, one of the largest remaining breeding colonies of olive
ridleys in the world. This take is reportedly increasing. Also, more than
100.000 eggs were reportedly taken in 1982 at Gahirmatha alone and sold in
Calcutta.
In other areas where olive ridleys are found, such as Pakistan and Sri
Lanka, the take of turtles for human consumption is very large. Also,
hundreds of thousands of eggs are removed from Ostional Beach, Costa Rica
each year. The removal of virtually all of the olive ridley eggs at
Eilanti, Surinam, by the Carib Indians up until the late 1960's may have
caused the drastic decline there.
In the United States, the olive ridley is protected by the Endangered
Species Act of 1973. It is listed as threatened throughout the world,
except the breeding colony populations on the Pacific coast of Mexico which
are endangered. Some large imports, such as Japan, have taken
reservations on this species which means they will still import
products from olive ridleys.
3. Disease and predation. Diseases and parasites of olive ridleys are not
well known. Predators of eggs, hatchlings, juveniles, and adults have
previously been identified. At Nancite, Costa Rica, an extremely low
percent hatch rate has been attributed to bacterial and/or fungal
contamination. The level of mortality from disease and predation and the
effect on the species are unknown.
4. Other natural or manmade factors affecting its continued existance.
The effects of natural forces on the continued existance of this species are
not known. However, natural forces that affect olive ridleys, especially
during the nesting process, include storms, temperature, rain, and wave
surge. These forces can create beach erosion or accretion, prevent turtles
from nesting, destroy eggs and hatchlings, and reduce nesting success. The
Life History - 5 (DRAFT) - Life History
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
build up of a huge mud flat in front of the major olive ridley nesting beach
in Surinam may pose a threat to the population nesting there.
An additional threat in parts of this turtles range is incidental catch by
shrimp trawlers. This is considered to be serious in the Pacific and in the
Atlantic and is believed to be a factor in the decline of the olive ridley
in Surinam. Other fishing gears are also believed to take olive ridleys.
Few, if any, of the activities and their effects outlined above have been
quantified; thus an evaluation of their impact, both singular as well as
cumulative, cannot be made at this time *91*.
REFERENCES FOR LIFE HISTORY- 91
Life History - 6 (DRAFT) - Management Practices
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Existing Prohibiting harvest of species being described
Existing Regulating harvest - setting bag/creel limits
Existing Regulating commercial harvest levels
Existing Other management practices [specified in comments]
Beneficial Controlling pollution [thermal, chemical, physical]
Adverse
Adverse Construction of navigational improvements [dams, locks, etc.]
Adverse Drilling
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 91
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 91
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 91
COMMENTS ON MANAGEMENT PRACTICES -
The local and commercial harvest of olive ridley populations for meat,
leather, and eggs is the primary cause of depletion. For example, this
species is the most economically important sea turtle in Mexico where legal
and illegal fisheries exist. In the five years prior to 1969, an estimated
2,000,000 olive ridleys were landed by the legitimate commercial fishery.
About 70,000 turtles were taken from La Escobilla in 1977, 58,000 in 1978,
and 24,500 in 1979. The main turtle processing plant in Mexico was
nationalized in 1981. Subsequently, the turtle quota set by the Mexcan
government for the 1981/82 season was increased by 72% over the previos
season and allowed a take of 69,000 turtles. By December 1981, 56,000
turtles had been taken. The quota for the 1983/84 season was set at 50,000
turtles. Only 26,000 turtles were taken by December 1983, and an additional
2,000 were taken be the end of January 1984, suggesting a substantial
decline in availability. The legal commercial harvest in Mexico is
overshadowed by poaching; millions of eggs and thousands of animals are
taken illegally each year--an estimated one million eggs were poached at La
Escobilla in 1969 alone.
From 1970 to 1977, between 132,000 and 147,000 adults were harvested in
Ecuador for the international skin trade. From 1978 to 1981, the harvest
increased to between 290,000 and 320,000 adults as estimated from the weight
(approximately 1,273,000 pounds) of skin that were exported. Although
Ecaudor banned the export of turtle products in 1981, Japan imported from
Ecaudor 18,623 pounds of skin in 1981, 74,272 pounds in 1982, and 6,600
pounds through October 1983. While commercial exploitation has at least
slowed in Ecaudor, there are some indications that this activity has now
shifted to Colombia.
In India, olive ridley populations are being depleted primarily by illegal
harvest of eggs and turtles for food and by human colonization of many
nesting beaches. Apparently, thousands of turtle are taken yearly off the
coast of Orissa, one of the largest remaining breeding colonies of olive
ridleys in the world. This take is reportedly increasing. Also, more than
100.000 eggs were reportedly taken in 1982 at Gahirmatha alone and sold in
Management Practices - 1 (DRAFT) - Management Practices
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
Calcutta.
In other areas where olive ridleys are found, such as Pakistan and Sri
Lanka, the take of turtles for human consumption is very large. Also,
hundreds of thousands of eggs are removed from Ostional Beach, Costa Rica
each year. The removal of virtually all of the olive ridley eggs at
Eilanti, Surinam, by the Carib Indians up until the late 1960's may have
caused the drastic decline there.
In the United States, the olive ridley is protected by the Endangered
Species Act of 1973. It is listed as threatened throughout the world,
except the breeding colony populations on the Pacific coast of Mexico which
are endangered. The species is also listed on Appendix I of CITIES which
bans the trade od its products. Some large imports, such as Japan, have
taken reservations on this species which means they will still import
products from olive ridleys.
Overexploitation for its meat, skin, and eggs, incidental take in various
fisheries, and alteration of nesting habitats has led to the depletion of
the olive ridley throughout much of its range. These factors continue to
deplete this turtle.
The NMFS believes the best available scientific and commercial data indicate
that most olive ridley populations are experiencing declines. Information
generated since the species was listed is insufficient to warrent a change
in the listing status with the exception of the nesting populations in the
western Atlantic (i.e., Surinam and adjacent areas) where the population has
declined more than 80% since 1967. Accordingly, it is the opinion of
researchers that the current threatened and endangered status of the olive
ridley should remain unchanged except that the nesting population in the
western North Atlantic (Surinam and adjacent waters) should be reclassified
as endangered. This change in listing is supported by numerous scientists
and conservationists working on sea turtle biology.
The NMFS, in coordination with the Fish and Wildlife Service should initiate
appropriate action to propose the above change in listing status *91*.
Factors that possibly affect the olive ridley population:
1. Present or threatened destruction, modification, or curtailment
of habitat or range
2. Pollutants from industrial and residential development
3. Exploratory oil and gas drilling
4. Disposal of garbage at sea
5. Dredge and fill operations
Management Practices - 2 (DRAFT) - References
Species turtle, olive ridley
Species Id M030001
Date 26 AUG 96
References
*91* Mager, A. 1985. Five-year status reviews of sea turtles listed under the
Endangered Species Act of 1973. U.S. Department of Commerce, National
Marine Fisheries Service, National Oceanic and Atmospheric Administration,
St. Petersburg, Florida. p. 56-69.
*121* Hopkins, S. R. (ed.), J. I. Richardson. 1984. Recovery Plan for
Marine Turtles. Hopkins, S. R. (ed.), J.I Richardson: 355.
References - 1