= Heavy impact from Gulf war
oil spills
Sirenews (ISSN 1017-3439) is edited by
Daryl P. Domning, Dept. of Anatomy, Howard
University, Washington, D.C. 20059
USA. It is supported by the Species
Survival Commission of IUCN, the U.S. Fish andWildlife Service, and the U.S.
Marine Mammal Commission.
Sirenews (ISSN 1017-3439) is edited by
Daryl P. Domning, Dept. of Anatomy, Howard
University, Washington, D.C. 20059
USA. It is supported by the Species
Survival Commission of IUCN, the U.S. Fish andWildlife Service, and the U.S.
Marine Mammal Commission.
NUMBER 15
APRIL 1991
IN THIS ISSUE: -
BRAZILIAN MANATEES BEING
COMMERCIALLY
EXPLOITED WITH GOVERNMENT'S
KNOWLEDGE (p. 6)
- PERSIAN GULF DUGONGS SO FAR UNAFFECTED BY
WAR AND UNPRECEDENTED
OIL SPILL (p. 11)
- FLORIDA
MANATEE CENSUS SUPPORTS
SCIENTISTS'
POPULATION ESTIMATE (p. 8)
EDITORIAL
In the six months since our last issue,
the world has seen a violent and tragic war unfold in the Middle East.
A complete reckoning of that
war's casualties may never be made;
indeed, at this writing the casualties,
to humans as well as other species, are still being inflicted. Spilled and burning oil continues to pollute
the air and
waters of the
Persian Gulf on an
unprecedented and almost
apocalyptic scale. Amid
this devastation, the news media have struggled to obtain
reliable information about the
impacts of these catastrophes on the biota of the Gulf, including dugongs.
(Indeed, if there is any scrap of gratification to be found in the aftermath of
the war, it may be that the existence of
the dugong has been made known through news reports to
millions of people who doubtless had never heard of the animal.)
In
this issue, Sirenews is pleased
to present what may be the most detailed
description of postwar conditions in the marine environment to have emerged so far from the Gulf - an
eyewitness account by Tony Preen, author of a recently-published monographic
study of dugong status in the Arabian
region. Tony is now once again in the Gulf, assisting with the evaluation and
cleanup of the oil-spill damage, and we are indebted to him for this timely
and authoritative report.
Happily, the news regarding the dugong is
good: no mortality or other direct
impact attributable to the spills - so far.
But the damage continues to
mount, and other species have suffered major blows. Meanwhile, elsewhere in
the world, the sirenian news is a similar mixture of good and bad. Dugongs are holding their own on remote Cape York, but the manatee body count continues to
climb in
the increasingly human-choked
peninsula of Florida, while the Brazilian government not
only fails to enforce its own laws protecting manatees but routinely tabulates
in its fishery statistics the number of tons of manatee meat sold
in Amazonian markets. We have a long way
to go. -
DPD
SIRENIAN WORKSHOP IN 1993?
The first Sirenian Workshop was held in
Edmonton, Canada in 1985 as part of the Fourth International
Theriological Congress (ITC). ITC VI
will be held in Brisbane, Australia in August 1993. Professor Michael Bryden and I have been asked to help
convene a symposium on Marine
Mammals. The details are not finalized
as yet, but we are
planning a symposium entitled "The
Status of Marine Mammals". This
would consist of a series
of invited reviews on the status
of species in major taxonomic groups,
plus posters on particular species.
I
suggest that it would also be timely to hold a
second Sirenian Workshop in association with this conference. A workshop
is more appropriate than a symposium for a small specialist group like ours.
The format would also consist of invited review papers and posters, as this is
the ITC style.
A DECISION TO GO AHEAD WITH THE WORKSHOP
WILL DEPEND ON YOUR RESPONSE. IF YOU ARE
INTERESTED IN COMING, PLEASE LET ME KNOW. ICANNOT GUARANTEE
ASSISTANCE WITH TRAVEL, BUT
IF THE
WORKSHOP LOOKS VIABLE, WE
WILL TRY TO OBTAIN ASSISTANCE
FOR POTENTIAL PARTICIPANTS FROM
DEVELOPING COUNTRIES. - Helene Marsh
EDUCATIONAL MATERIAL ON
DUGONGS
The Fisheries Branch of the Queensland
Department of Primary Industries
has produced educational
modules on dugongs
and seagrasses. The modules consist of student activity
sheets and teacher's guides.
The material is
aimed at primary
school students. Copies can be
obtained from Ms. Dawn Couchman, GPO Box 46, Brisbane, Queensland 4001,
Australia.
LOCAL NEWS
AUSTRALIA
Status
of Dugongs off the East Coast
of Cape
York. - In November 1985, I carried out an aerial survey over 31,288
square kilometers of northern Great Barrier Reef waters off the
east coast of Cape York. This resulted in a population estimate for the region of 8110 +_ s.e. 1073 dugongs.
The Great Barrier Reef
Marine Park Authority accepted my
recommendation that the survey be
repeated after five
years and funded another
survey in November-December
1990. As a result of this survey, we
estimated that there were
10,472 +_ 1579 dugongs
in the region;
the difference between surveys was not significant. The distribution of dugongs was very similar
for the two surveys. I conclude that
dugong numbers have not declined in this region in the last five years.
Anthropogenic impacts in this region are low as it is very sparsely
populated. The major impacts are probably incidental drownings in gill nets
and traditional hunting
from two communities. On the basis of the data on this traditional catch that
Andrew Smith collected between 1984 and 1987, he
and I concluded that
it was likely to be sustainable, a
conclusion supported by the results of my recent survey. -
Helene Marsh
Mating Herd off Cape York. - In October and November 1988, Tony Preen observed the mating behavior
of dugongs in Moreton Bay in southern Queensland (Marine Mammal Science 5: 382-387, 1989). The behaviors he described had many similarities
with those of the mating herds of West Indian manatees,
but the competition for oestrous females was more intense and more
violent. In contrast, Anderson (Sirenews
No. 11, April 1989) reported that in Shark Bay on the other side of
Australia, dugongs make use of a lek
mating system. Individuals patrol
mutually exclusive territories
and defend them through displays and combat. This difference between the mating behaviors of dugongs in different
geographical areas is very interesting
but not unprecedented, as lekking in
mammals has so far
always been found to be facultative
rather than obligatory.
What happens in other areas? In hundreds of hours of aerial survey in
northern Australia, mostly in October
and November, I had never
seen mating dugongs.
However, on 12 December 1990, during the aerial survey of the waters
off Cape York (see above), we saw a dugong mating herd in water about 22 m deep
about 22 km off the coast east of the mouth of the Stewart
River (14 04' S, 143 41' E) in Princess Charlotte Bay. This is the locale of the famous paper
written by Donald Thomson on the
basis of his research
in 1928 and entitled "Dugong hunters of
Cape York" (Jour. Roy.
Anthrop. Inst. 64: 237-264,
1934). As described by Thomson,
dugongs are fairly numerous in this area but tend to occur in small groups. Although it was out of our transect,
we were attracted by the size and
behavior of this herd and decided to
abort the transect.
We circled the herd for about five
minutes. A tight group of five or six
animals was surrounded by a dispersed aggregation of 18 others.
Animals in the central group were creating a
great deal of splash as four or
five animals attempted to cling to and mount the focal animal, presumably a cow in oestrus. This animal was
in an upright horizontal position just below the surface. Up to three animals were ventral side
up, attempting to dive under the
cow. The two animals closest to
the mounted group were also very
active, and I have photographs of
one ramming the side of the other with
its head. The other animals were
swimming around actively and showed no
evidence of feeding behavior. The behavior of this group is very similar to
that observed in Moreton Bay. We still need information from other areas. -
Helene Marsh
BRAZIL
Activities
of the INPA Aquatic Mammal
Laboratory. - The Laboratory of
Aquatic Mammals at the
National Institute of Amazonian Research (INPA) in Manaus began
its activities in 1974 with a single
captive manatee. After 1976 it broadened
its range of studies to include Amazonian river dolphins, otters,
and the ariranha (giant otter).
The number of manatees held in captivity also increased.
Presently we have 11 captive animals (5 females and 6 males), including a male calf about 6 months old
which is being fed an artificial milk
formula developed by us.
The
captive manatees have been used in a series of studies on their physiology, food preferences, annual variations in the aquatic macrophytes
constituting their diet, and the
nutritional constituents of these
plants. Also studied have been daily
food consumption, anatomy of the
digestive tract, nursing of calves,
dispersal of seeds of aquatic grasses by manatees, cytogenetics, hematology and
blood biochemistry, age
determination, craniometry, and diseases.
Some
studies are still in
progress, among them those
of craniometry, grass-seed dispersal
by manatees, and
age determination. New projects
are being elaborated for 1991, 1992, and
1993, involving the present status of the manatee in the
Brazilian Amazon, radiotelemetry in
the wild, histological, anatomical and physiological
studies of the digestive tract, and
endocrinology.
We
are presently finishing the construction of
our new aquatic park.
One of the manatee tanks is already in the final stage of construction, and the rest
should be completed in 1991.
Our
research team presently
includes the following personnel: Vera Maria Ferreira da Silva, M.Sc.;
Fernando Cesar Weber Rosas,
M.Sc.; Elton Pinto Colares, B.Sc.; Ioni Gonc,alves Colares, B.Sc.;
and Francisco Antonio Pinto Colares, B.Sc. Ioni is scheduled
to defend her master's thesis (on food
habits of Trichechus inunguis)
in February 1991; Elton is scheduled
to defend his (on physiology and biochemistry of blood plasma in T. inunguis) in March 1991. - Ioni
Colares
West
Indian Manatee Project. - Monica
Borobia reports that the West Indian manatee project based in Paraiba, Brazil,
seems likely to be reinstated.
Its status has been changed; it
is now called the "Centro
de Estudos e
Conservac,ao de Sirenios" (Sirenian Research and
Conservation Center) and is directly under the umbrella of IBAMA (Brazilian
Institute of the Environment and Renewable
Natural Resources). Along with
foreign funding, this must have
significantly improved the project's financial support, given the
considerable improvement in
its field base installations and equipment since the
time when Monica worked in Barra de Mamanguape. In addition,
an office has been set up in Joao Pessoa, the capital of Paraiba, one hour away. Worth
noting is the well-planned
conservation/education campaign directed
to coastal communities of the Brazilian Northeast. However, it seems
that research efforts have been mainly
concentrated at Barra de Mamanguape.
There
is increasing and
encouraging evidence of
manatee presence in other parts of the Northeast,
including southern Bahia where manatees had not recently been known
to occur. For example,
Monica sent photos of a manatee rib she found in the zoological collection
of the Federal University of
Alagoas in Maceio'. It
appears to be quite broad (more than 5.5 cm) in its midsection, as is characteristic of Trichechus
manatus. She feels that these records
should warrant an in-depth
survey of the entire
region, and that a
good look might yield
surprising results, as has
been the case for other aquatic
mammals in Brazil, such as Pontoporia.
Manatees Still Commercially Exploited in
Brazil. - A not-so-encouraging aspect of
Monica Borobia's report is that commercial hunting of manatees may actually be
continuing in Brazil with the knowledge
and apparent approval
of that country's
federal government. She quotes the following excerpt of a letter to
her from the well-known Brazilian
conservationist Admiral Ibsen G. Camara, dated 12 March 1990 (her
translation):
"It's
interesting that the Anua'rio
Estati'stico do Brasil [the
official government compilation
of commercial data, published by
the Instituto Brasileiro
de Geografia e Estati'stica], year
1989, shows in the fisheries
statistics, 7 tons of manatee for
1985, 2 for 1986 and another 2 for
1987; it is probably from T. inunguis,
but in any case it's surprising
that a protected species should be
included in the [statistics on] fisheries production."
This
news prompted a look at earlier volumes of the Anuario Estatistico,
which yielded the following data:
_________________________________________________________________
Species Year Catch
(tons) Value (Cr$1000)
Total Freshwater
Total Freshwater
_________________________________________________________________
Aquatic mammals 1970
8074 54 3260 52
"
" 1971 9813
63 4420 76
"
" 1972 3069
14 2291
27
"
" 1973 7375
55 4122 114
"
" 1974 6568
-- 5610 --
Cetaceans 1975
6631 -- 6498 --
" 1976 5816
-- 4045 --
" 1977 4120
-- 4120 --
" 1978 3700
-- 9920 --
" 1979 3064
-- 26440 --
Manatee 1980 5
5 0 0*
" 1981 14
14 1 1
" 1982 19
19 2 2
" 1983 5
5 1 1
" 1984 9
9 10 10
" 1985 7
7 18 18
" 1986 2
2 26 26
_________________________________________________________________
* Note:
From 1980 on, the
units of value are
millions of cruzeiros rather than thousands.
The
data compilations for the years
1970 to 1974 do not
specify what sort of freshwater aquatic
mammals are included in the catch,
the bulk of which comprised whales.
Presumably the freshwater mammals
were T. inunguis. Manatee hunting was
totally banned in Brazil
in 1973, whereupon the
reporting of such statistics as the above (though not, of
course, the actual hunting) abruptly ceased (see Domning,
Biol. Conserv. 22(2): 101-126,
1982). From 1975 to 1979,
the data category for aquatic
mammal production was accordingly labeled simply "Cetaceans", and all
the production in this category was attributed to salt water. Beginning with 1980,
however, the
"Cetaceans" category (later
renamed "Aquatic mammals") was
explicitly broken down
into "Whale" (data not
shown here) and "Manatee", and
production of manatee products
(presumably meat, and all from fresh
water) was again officially reported.
The federal government's ban on hunting
of both T. inunguis and T. manatus was reiterated on February 21,
1986 (Portaria SUDEPE No.
N-011). (The text of this
regulatory decree can be found in FBCN/Informativo [Rio de Janeiro, Fundac,ao
Brasileira para a Conservac,ao da Natureza] 10(2), April-June, 1986.)
Yet the commercial exploitation of
manatees continued throughout the 1980's,
obviously with the government's knowledge
since the statistics quoted
above were published by the government, and were still being published as of 1989.
Monica comments that this seems to be a
prime example of the unfortunate
lack of law enforcement on the part of
Brazilian government agencies.
Hopefully, researchers at the two manatee research centers
in Brazil can investigate the origin of
these statistics. In any
event, government agencies
capable of gathering statistics on illegal fishing activity should
be able to do more in the way of putting
a stop to it. In the opinion of Sirenews, it
would be desirable for
the Brazilian agencies concerned (such as IBDF and SUDEPE)
to take more seriously their responsibility
to enforce their country's existing laws and their own regulations - especially at a time when
preparations for the U.N.
Conference on Environment and
Development, to be held in Brazil
in 1992 (see Sirenews No.
14), are focusing
increased world attention on Brazil's conservation track record.
CARIBBEAN REGION
Outlook
for Manatee Survival Grim Unless
Rapid Action is Taken.
- In September 1989, [after]
answering a call for a live manatee
stranding in Puerto Rico, the
local police informed us that the caller had stated: "There is a live manatee on shore; can
we shoot it so we can eat it?" Upon
[our] reaching the locality to assess the situation, the manatee was not found. We concluded that poachers got there first.
Four months later, an adult manatee was found floating dead with
no obvious evidence of cause of death.
Upon examination, it was
determined that the animal was carrying an almost full-term fetus, and that she died from a
boat collision which ruptured her internal
organs. Death cases in Puerto
Rico also attributed to the same cause occurred in 1988, 1989,
and this past October 1990.
Traveling
to Colombia in April 1990, I
examined a manatee captured by
local fishermen, which was sold for $300 to the
Barranquilla Zoo, where
it is kept
for exhibition. Local biologists worry for its health given
that it is in a very small and shallow
tank without a filter, and it has a fractured flipper and other infected
wounds.
In October 1990, I visited the city market
in Santo Domingo, Dominican
Republic. I wanted to see for
myself if there was an actual market
for manatee bones, in addition to the
use of manatee meat
as food. To my surprise, different
stores sold polished and
carved manatee ribs mounted on wood
stands. They also sold manatee
oil for treating chest colds. One of the
store owners took me in the storage
area, where I saw a box
holding about 50 to 75
ribs and vertebrae to be processed
during the following days.
Pressures such as these are
greater than the small
localized manatee populations
in the Caribbean
can withstand. Studies conducted
in the late 1970's and in
1984 suggest that only
100 to 200 manatees exist
today off the Caribbean islands.
This
endangered status, probably compounded by a genetic bottleneck and low reproductive
rate, is aggravated by up to six
reported deaths each year for the past
15 years. The 45 deaths reported since
1975 do not include those
manatees taken by poachers for their meat. During the Christmas holidays, it is a tradition for
some families living in coastal areas
to eat manatee meat. The leading causes of manatee mortality are
human-related, either by
poaching, incidental takes,
or boat collisions. Most deaths
were thought to be due to accidental gill net
entanglement, but recent research
revealed that these nets are set
specifically to catch manatees for human consumption....
It
is only through research, education and the type
of cooperative action exhibited by the creation of the
Caribbean Stranding Network [see Sirenews
No. 14]
that the Antillean manatee will
have a chance to survive throughout
its entire range. -
Antonio A. Mignucci Giannoni (reprinted by permission from the Save the
Manatee Club Newsletter, March 1991)
FLORIDA
Synoptic
Manatee Aerial Surveys.
- Nearly simultaneous aerial surveys
throughout the State of
Florida and parts
of southern Georgia, made in an
attempt to count as many individual manatees
as possible, have yielded a maximum count
of 1,465 animals, in close
agreement with the previous minimum estimate of 1,200 manatees in the state.
On
23-24 January and again on 17-18 February, more than 30 biologists, representing 19 local, state, and federal agencies, private research
groups, and independent
contractors, were mobilized by
the State's Department of Natural Resources (DNR) in an all-out effort to count manatees. Counts were made from
25 planes and 3 helicopters in the first survey; 26 aerial
teams participated in the second.
Two ground crews also aided in
each survey. Each team
included a biologist experienced in
manatee aerial surveys. The surveys were planned to follow in the wake
of cold fronts, when many manatees would be concentrated at warm-water sources. A prolonged cold spell would have
provided ideal conditions for the
census. However, the past winter was a mild one in Florida, and the two cold fronts
used for the surveys were not as severe
as many in the past; but the survey coordinators judged that
no better opportunities were likely to
occur this year. The
survey teams had been designated and on standby since 15 December.
The
January survey yielded a preliminary total count
of 1,268 manatees, 679 on the
east coast and 589 on the west coast of Florida.
The February survey, which
enjoyed more favorable conditions
following a more severe cold front, counted 1,465 (813 on the east coast and 652 on the west). The second survey also included some areas not covered the
first time, such as a naval base
previously off limits due to
preparations for the Persian Gulf war, power plants where overflights had been
restricted for fear of terrorist attacks, and other areas missed because
of aircraft engine problems or bad weather. These raw figures may be
reduced slightly by removal of
probable duplicate sightings. Although both surveys concentrated on areas known to
be used by manatees as warm-water refugia, the intervening areas of rivers and coastal
waters were also surveyed. The
results of both surveys
were consistent with
each other and
with previous knowledge of manatee habits and distribution: manatees
in the colder northern part of the state were concentrated
at refugia, whereas in the south they
were more widely dispersed.
The
total counts were in close agreement with the
minimum population estimate of
1,200, which was based on compilation of
data from non-simultaneous surveys of
the individual warm-water refugia. That estimate had been revised upward in 1985
from the previous minimum estimate of
1,000.
The
simultaneous statewide surveys were first planned three years ago,
but were not carried out until now due to unusually warm winters in the last two
years. The surveys were a response to public pressure, particularly from boating industry spokesmen
who opposed the increased regulation of
boating being urged for the sake
of manatee protection.
They contended that
the biologists' minimum estimate
of only 1,200 Florida manatees was much
too low and that tightened regulation was unnecessary. They argued that, in fact, no one really knew how many manatees
there were and hence there was no reason to think they were endangered.
Manatee biologists, for their part, were generally critical
of the
proposed statewide census, on several grounds.
They pointed out that what was
important to conservation efforts was
not the
total number of
manatees, but the
trend in the numbers
over time. This
trend could only be established
by surveys repeated, with
consistent methods, over
five to
ten years. The one-time census proposed would not be statistically comparable to any survey done in the past,
and because the results
would be expected to vary with the intensity of
cold fronts, it would
be difficult or impossible to
replicate the conditions of the
census in future years. Moreover, the
cost and the daunting logistical complexity of the census would discourage
repeat attempts. The biologists argued
that continued monitoring of the known
manatee aggregation sites by the long-established survey methods
already in place would yield a more accurate picture of any
population trend, and probably just as
good an estimate of the
total population size, at much lower
cost and effort. Finally,
they noted that, given any
plausible model of manatee population dynamics,
the present mortality rate of
over two hundred animals a year (see below) could not be consistent with population stability. They feared that whatever number
a census produced, whether
accurate or inaccurate,
would be misinterpreted by
the public and used to
obscure these basic facts that dictated strengthened
conservation measures regardless of the actual number of manatees.
Caught
in the middle of this
controversy, DNR eventually yielded to the
political pressures and organized the
census. Fortunately, the result has vindicated the biologists'
previous population estimates and
provided no comfort to the
boating lobby. Although the new minimum count of 1,465 manatees
exceeds the previous minimum estimate of
1,200, this doubtless resulted from
increased survey effort and cannot be interpreted as a sign of a population increase, nor is it out
of line with any previous thinking on the part of manatee researchers. All who
have studied the relevant data agree that the manatee population in Florida is
most likely declining,
due to high
rates of human-caused mortality and habitat loss (see
below).
The
census also stands as
another, and perhaps the
most dramatic, landmark in
the long and
laudable history of interagency cooperation
on behalf of the Florida
manatee. Dr. Bruce Ackerman, the project leader, and his collaborators had
to overcome what they termed "horrendous" logistical
difficulties - as will be appreciated by anyone experienced in
such operations. For this they
deserve the applause of all
those involved in sirenian conservation. - DPD
New All-time Manatee Mortality Record. -
The Florida manatee salvage program has once again, for the third consecutive year, logged
an unprecedented number of dead manatees. The 1990 grand total was 206,
compared with 166 in 1989 and 133 in
1988. The previous maximum was
128 in 1984.
The
new mortality peak in 1990 was due largely to a
major cold-related manatee kill in winter 1989-90.
However, human-related mortality also remained high. Boat kills
numbered 47, only slightly
below the 1989 record of 50.
There were also 3 deaths
in flood gates or canal locks,
and 4 other human-related deaths.
Perinatal deaths also set a disturbing new record of 44, surpassing the 1989 record of 36. 66 other
natural (including
cold-related) deaths and 42 of undetermined causes made up the total of 206.
Meanwhile,
the 1990 U.S. Census showed that
nine of the 12 fastest-growing
metropolises in the
United States were
in Florida. Seven of
these nine are coastal cities
within the manatee's year-round
range: Naples (which grew by 77%
since 1980), Fort Pierce (66%),
Fort Myers (63%), West Palm
Beach (50%),
Melbourne-Titusville (46%), Daytona
Beach (43%), and Bradenton
(43%). The inland cities of Ocala
and Orlando grew by 59% and 53%, respectively. Florida now has three cities
with over 1 million people: Miami
(3,192,582, up 21% since 1980),
Tampa (2,067,959, up 28%), and Orlando (1,072,748). To a large extent
this growth was fueled by retirees.
Watercraft-related manatee deaths in Florida during 1986-90
showed a 68% increase over the previous
5-year period (1981-85) and a
124% increase over the
period from 1976
to 1980. -
(Sources: Florida Dept. of Natural Resources and The Washington Post.)
INDIA
Dugongs
and Ganges River
Dolphins Featured on
Postage Stamps. - Postage stamps
featuring the river dolphin (Platanista gangetica; denomination Rs.4.00) and the dugong
(Rs.6.50), along with a first-day cover showing the common
dolphin (Delphinus delphis), were
released by the Indian
Postal Department on 4.3.1991
at Cochin, India. The proposal for the stamps and the
basis for the designs were provided
by Dr.
R. S. Lal
Mohan, Principal Scientist of the
Central Marine Fisheries Research Station, Calicut,
and a member of the IUCN Cetacean
Specialist Group. He also
provided the write-ups on the
animals for an accompanying brochure.
This
is the first time an aquatic
mammal stamp has
been issued by India. It is also the first time a stamp has
featured the Ganges River dolphin. One million stamps were printed
and kept for sales all over
India. They were released by Justice K.
Sukumaran of the Kerala High Court. The ceremony was announced in the newspapers
and well covered
by nationwide radio
and television. The stamps are intended to create awareness among the
people, as many
of them are not even aware
that the river dolphins are found in the Indian rivers Ganges
and Brahmaputra, or that
the dugong is distributed along the southeast coast of India.
It is hoped that these stamps will help in the efforts to protect these
animals.
MEXICO
National
Manatee Research Program.
- Mexican marine
mammalogists assembled at the
Workshop on Marine Mammals
in Mexico City, 15-17 October
1990, elaborated a National Program for
the Investigation, Conservation and Management of
Marine Mammals in Mexico. As part of this program, a group of workers interested in
manatees proposed a project
entitled "Situacion
Actual, Ecologia y Conservacion del
Manati Trichechus manatus en el
Sureste de Mexico [Status, Ecology and Conservation of the Manatee
in Southeastern Mexico]." Any researchers interested in collaborating on
this project are
encouraged to establish communication with Luz Colmenero
at her new address given below.
PERSIAN GULF
Dugongs
Threatened by Kuwait Oil Spill. - As all
of our readers are by now aware, the massive oil spills resulting from
the war in the Persian Gulf have caused
extensive damage to the environment and
wildlife of that shallow, landlocked
sea. Up to this point,
however, casualties among
the Gulf's dugong population have fortunately been
nonexistent.
The actual size of the spill is
itself, of course, still in doubt. In early April, press reports of official estimates gave its
volume as at least 1.5 million barrels,
with the possibility that it may eventually
prove to be between 4 and
7 million barrels - in any event,
the largest such disaster in history.
Dugongs
were not among
the organisms most
immediately threatened. According to Tony Preen's 1989 study of dugong
status
and conservation in
the Arabian region
(Saudi Arabia, Meteorological
& Environmental Protection Administration
Coastal and Marine Management Series Report No. 10, 2 vols.), they do
not normally occur in the waters of Iran,
Iraq, Kuwait, or northern
Saudi Arabia north of Ras Tanura (near
Dhahran). Dugongs in the Gulf are
mainly found along the
western and southern
coasts between Ras Tanura and Abu Dhabi. One of
the most important dugong areas,
and the only one likely to suffer
significant impacts from the
spill, is the Gulf of Salwa, which
separates Saudi Arabia from
western Qatar and surrounds
the island of Bahrain. Preen estimated the dugong
population of the entire Gulf at 7307 +_ s.e.
1302 (coefficient of variation 17.8%).
About 54% of this population
was located in the Gulf of
Salwa during Preen's summer aerial
surveys (August and October 1986).
So
far, the oil slicks have moved
slowly, and the shores most
affected have been those well to the north of Ras
Tanura. With time and the approach of warmer weather, the oil
can be expected to
partly evaporate and partly sink;
and the lack of heavy wave and
current action should tend to keep most of the oil concentrated north of the
major dugong habitats. On the negative
side, of
course, the wildlife habitats where the oil remains suffer correspondingly heavier
damage, and cleanup work is very limited in scope and proceeding slowly.
Of
uncertain import is the fact that the northern Gulf was heavily polluted by oil even before the
recent war. Preen pointedout the possibility
that chronic low-level
exposure to hydrocarbons
"may in the long-term be the most damaging effect of petroleum pollution
on dugongs in the Gulf." Given the additional fact that extreme salinities and low winter water
temperatures make the Gulf to
some degree a marginal and possibly stressful habitat for
dugongs to begin with, the new
spills "could more readily exceed
the tolerance limits of dugongs in
this region than in
other areas, where environmental
conditions are less extreme."
The foregoing may provide useful
background to the following on-the-scene report from our special correspondent, who has gone to the Gulf to study the
situation at first hand. - DPD
Gulf
War Oil Spill: A Situation Report. - I have been
in Saudi Arabia since 25
February, assisting with the response to the Gulf war oil spills. The following is a brief account of the
situation.
The oil spills commenced on 19 January
1991. At least seven sources are
known, including tankers, terminals and refineries. Early estimates of
spill volume, based on remote sensing,
ranged from 5 to 11 million barrels. Measurements of tank capacities and
pumping rates have not been
obtained, but two vessels known to have
been deliberately emptied each contained 1 million barrels. To date
no consensus estimate has been determined, but
it is likely to be on the order
of 6 million barrels.
At the time of writing (5 April
1991), oil continues to be discharged from several sources. Total discharge is estimated at about 3000 +_
1500 barrels per day.
The
spills have resulted in two types
of slick: (1) very thin slicks, located in the center of the Gulf, and (2) a
very thick slick which impacted the Saudi coast. A series
of thin slicks, composed of small
amounts of oil (10,000-20,000 barrels), formed large areas (thousands of square
kilometers) of sheen with streamers and
patches of thicker oil mousse. These
slicks have gradually moved southeast, down the center of the Gulf. In the process they
have impacted some of the
offshore islands and, recently, the north and northwest coasts
of Bahrain and Qatar. As a result, 80%
of the shoreline of Karan Island was covered
with thick oil. After five days of impact, beaches of north Bahrain were very lightly oiled with about 3% cover of
fresh tar balls (up to golf ball size).
By
far the majority of the spilt oil moved south along the Saudi coast, eventually impacting all the shoreline north
of Abu Ali, a coastline
distance of 460 km (see
map). This coast includes open beaches and complex,
low-energy embayments. Along a transect from dry land into the water, these embayments contain: algal mats,
irregularly inundated saltmarshes, regularly inundated saltmarshes, some
relict patches of
mangroves, intertidal mud/sand flats,
subtidal seagrass beds and occasional patch coral reefs.
Effects on habitats. Along sandy beaches
the oil occurs in a band 10-100 m wide.
Surface coverage within bands is about 100%. On the beach slope the oil
has been worked into the sediment to a depth
of 2-30 cm. At the base of the beach slope the oil
has often pooled to depths of several centimeters.
The
intertidal and supralittoral
zones have been
very heavily impacted. Oil has been driven by wind and high tides into
the most
distant reaches of the saltmarshes. Over
scores of square kilometers
the oil lies 500 m to 1 km
landward of the normal mean high water line. Surface coverage is 100%. I know of one
location where the oil has been driven inland 5 km beyond the shore.
The
saltmarshes and mangroves have
acted as natural traps for the oil. Within the 460 km of impacted coastline, only
one patch of saltmarsh has not been oiled. All the mangroves have been
oiled. Hence all
the mangroves and virtually
all the saltmarshes will die.
Oil
has now settled in large patches on intertidal mud/sand flats. The oil
has not settled in subtidal areas and there are no apparent short-term
lethal impacts of the
pollution on the seagrass beds or reefs. Similarly, the intertidal shores of some
offshore coral islands have been heavily impacted, but the reefs appear to be unaffected.
Effects
on wildlife. By the time the oil
struck the Saudi coast, most of the
toxic compounds had apparently evaporated, and its main impact on organisms has
been by smothering. Hence there has been
less mortality of marine fauna than was expected.
The
most obvious mortality has been among the seabirds. In particular, the regionally endemic Socotra cormorant as
well as the Great cormorant and the
Black-necked and Great-crested grebes have suffered. A total mortality of 20,000-30,000 birds has
been estimated. During the peak period in February, 90 oiled
birds were brought to the Wildlife Rescue Center each day.
Marine
mammals have not been significantly affected by the oil.
Dugongs do not normally occur
within the heavily-impacted area - their range commences 120 km south of Abu
Ali. There has been no
significant mortality of dolphins.
I have seen
many humpback dolphins (Sousa
chinensis) and bottlenose
dolphins (Tursiops truncatus) near oil,
and I have seen several Sousa chinensis surfacing through oil
sheen. At least two dolphins and one
dugong have died during the spill. These
all died well south of the main
spill area and there is no evidence
of a causal relation. Early
plans to capture the
dugong population and relocate it to Oman have been
reconsidered.
At least three turtles (two green and one hawksbill) have died in oiled areas. Cause of death was not determined. Two green turtles have been treated at the Wildlife Rescue Center and released.