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)
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
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
A DECISION TO GO AHEAD WITH THE WORKSHOP WILL DEPEND ON YOUR
RESPONSE. IF YOU ARE INTERESTED IN COMING, PLEASE LET ME KNOW.
CANNOT 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.
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
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.; loni 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
Species Year Catch (tons) Value (Cr$1000)
Total Freshwater Total Freshwater
Aquatic mammals 1970 8074
" 1971 9813
" 1972 3069
" 1973 7375
" 1974 6568
Cetaceans 1975 6631
-- 4045 -
-- 4120 -
-- 9920 -
* 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
54 3260 52
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.
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
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)
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
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.
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.)
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
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.
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.
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
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
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
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. They had ingested oil and were very ill when captured. A small number of sea snakes
(I counted 11 along 5 km of shore) died on Karan Island as a result of smothering by the oil.
Very few dead sea snakes have been seen along the mainland coast.
Fish mortalities have been localized. Shrimp, crabs and molluscs have been the most
conspicuous invertebrate victims, all dying in huge numbers.
The direct impacts from oiling and the impacts from loss of intertidal habitats are expected to
have a major impact on the populations of wading birds which migrate through or reside in the
Gulf. An estimated 1-2 million waders representing 70 species use the area. Mortality is
expected to be small in the Gulf, but high mortalities are predicted en route to Siberia and Europe
for waders with oiled feathers. Those that do complete their migration may not have the
energy reserves to breed.
Recovery and cleanup. The Exxon Valdez spilled 224,000 barrels of oil. So far, over
600,000 barrels of oil have been recovered from the Gulf war spills. A flight along the coast,
watching kilometer after kilometer after kilometer of oiled coastline, is ended with a pass
over the principal storage pit for collected oil. The absolute insignificance of this quantity,
compared to what is still along the shoreline, is absurd.
Due to the magnitude of this spill, the types of habitat impacted and the extreme
inaccessibility of some areas (saltmarshes backed by kilometers of often treacherously
boggy saltpan), it is unrealistic to expect that much of the coast will be cleaned. We are now
identifying the most important sites, which upon recovery may act as sources of propagules
for the recolonization of other sites. The recovery of the saltmarsh and mangrove habitats will
doubtless take decades, if they ever return to their previous state.
Cleanup of selected habitats is about to begin. By the end of April the gross oil and oiled
sand will be removed from the beach of Karan Island, the most important green turtle rookery in
the Gulf and an important nesting site for three species of tern. The flushing of free oil from the
mangroves of Ghurmah Island will commence in a few days and the washing of some
saltmarshes in Dawhat ad-Dafi will begin in about one week.
A final concern worthy of mention regards the oil fires in Kuwait. A huge volume of oil is
not burning and is forming huge lakes. It is feared that these may eventually flood into wadis
and into the Gulf, potentially creating a spill of even greater magnitude. Anthony Preen
(International Environment Team of the Oil Spill Response Group and Zoology Dept., James
Cook University, Townsville, Australia)
Adding Insult to Injury; or, How Much Worse Can It Get? Colin Bertram has called our
attention to the following item, here quoted from New Scientist, 24 November 1990:
"A strange tale appears in The Guardian of teenage heroes (Our Boys in the Gulf) and
mutant turtles. Apart from the pollution arising simply from the presence of 300 000 troops in
the desert, the paper's Environment section reported last week, a war would threaten the local
dugongs. 'These marine turtles are right in the frontline ... Mutant turtles are a distinct
"Now, it never does to mock ... but what the hell: once dugongs have mutated into turtles,
maybe a second mutation would be that much easier."
Caribbean Stranding Network Activities. Network participants from the Puerto Rico
Department of Natural Resources salvaged the bones of a badly decomposed large manatee
from Levittown, Puerto Rico, in late January 1991, while Antonio Mignucci and three
student volunteers necropsied a manatee that had been butchered by humans near the mouth of
the Rio Loiza.
Ruby Montoya, a young manatee researcher from Colombia, began working on her four-
month internship on marine mammal health at the Caribbean Aquatic Animal Health Project
laboratory (University of Puerto Rico, Lajas). (Excerpted from Summary 7 of the Marine
Ecological Disturbance Information Center, UPR, Lajas, 10 Feb. 1991.)
The Ecology of Manatees in Georgia with Emphasis on Cumberland Sound (Barbara J.
Zoodsma & Lynn W. Lefebvre). Although sighting reports indicate that manatees are not
uncommon in southeast Georgia, little was known about their distribution and ecology in this
region, which represents the northern limit of their typical range. A 3-year radio-tracking
study was conducted from the spring of 1987 through the summer of 1990 to investigate the
ecology of manatees along the southeast coast of Georgia, and to evaluate the potential effects
of dredging on manatees in Cumberland Sound and Kings Bay, Georgia. Fourteen manatees
were radio-tracked for varying amounts of time during the study: 8 manatees were captured
and radio-tagged in Fernandina Beach, Florida; 5 manatees radio-tagged in Brevard County,
Florida, migrated to Georgia during the warm season; and one manatee was radio-tagged in
Kings Bay, Georgia, in 1989. Weekly aerial surveys were conducted from May through
September, 1988, and April through August, 1989, to determine manatee distribution in
Cumberland Sound and Kings Bay. Microhistological analysis was performed on the stomach
contents of 15 dead manatees which were recovered in Georgia.
Georgia salt marshes are an important manatee habitat. Some of the manatees that winter in
Florida return to Georgia in repeated years during the warm season. Manatees feed primarily on
Spartina alterniflora, which is only accessible to them during high tide, and the macroalgae
Ulva spp. and Gracilaria spp. Manatee activity patterns are rhythmic in response to tidal
cycles: manatees feed on Spartina most often at high tide, and rest or cavort at low and mid-tide
in both cold and warm seasons. Manatees spend a significantly greater proportion of time resting
in a man-made warm water source at low tide than at mid- or high tide in the cold season,
presumably to conserve energy. Aerial surveys as well as radio-tracking indicated that
Cumberland Sound, Kings Bay Naval Submarine Base, Tiger Island Marsh, and the Fernandina
Beach waterfront are some of the areas in and near Georgia which manatees frequent in the warm
season. The Satilla and Altamaha rivers, north of Cumberland Sound, were also visited by
several radio-tagged manatees. Potential negative effects of dredging on manatees can be
minimized by providing for manatee watches on dredges, requiring support vessels to move
at slow speeds, avoiding dredging in manatee feeding areas, and monitoring the effects of
dredging on the salt marsh shoreline and benthic macrophytes, particularly in known manatee
feeding areas. [Summary of a report to the Florida Cooperative Fish and Wildlife Research
Anonymous. 1989. A refuge for manatees. Florida Naturalist 62(4): 1 p.
Ackman, R.G., and F. Lamothe. 1989. Marine mammals. In: R.G. Ackman (ed.), Marine
biogenic lipids, fats and oils. Vol. 2. Boca Raton (Florida), CRC Press, Inc. (viii + 495): 179-
Bajpai, S., S. Srivastava, and A. Jolly. 1989. Sirenian- moerithere dichotomy: some
evidence from the Middle Eocene of Kachchh, western India. Current Science 58(6): 304-306.
Brown, D.O. 1991. Siren song. Calypso Log, April 1991: 14-16.
Buergelt, C.D., R.K. Bonde, C.A. Beck, and T.J. O'Shea. 1990. Myxomatous
transformation of heart valves in Florida manatees (Trichechus manatus latirostris).
Jour. Zoo & Wildlife Med. 21(2): 220-227.
Buffre'nil, V. de, A. de Ricqles, C.E. Ray, and D.P. Domning. 1990. Bone histology of
the ribs of the archaeocetes (Mammalia, Cetacea). Jour. Vert. Paleo. 10(4): 455-466.
Chow, B.A. 1991. Diet and the West Indian manatee. Jamaica Naturalist 1: 36. [Very
brief popular account of manatee digestion.]
Correa-Viana, M., T.J. O'Shea, M.E. Ludlow, and J.G. Robinson. 1990. Distribucion y
abundancia del manati, Trichechus manatus, en Venezuela. Biollania 7: 101-123.
Court, N., and J.-J. Jaeger. 1991. Anatomy of the periotic bone in the Eocene proboscidean
Numidotherium koholense: an example of parallel evolution in the inner ear of
tethytheres. C.R. Acad. Sci. Paris, 312, Ser. II: 559-565. [Sirenian-proboscidean
Ferrer, L.T., and A.R. Estrada. 1988. Primer record de mortalidad del manati en aguas
cubanas. Misc. Zool. (Havana) #41: 1-2.
Freeman, J., and H. Quintero. 1990. The distribution of West Indian manatees (Trichechus
manatus) in Puerto Rico: 1988- 1989. U.S. Dept. of Commerce, Natl. Tech. Information
Serv. Document No. PB91-137240: iv + 38. [Contract report to U.S. Marine Mammal
Furusawa, H., and Numata Fossil Research Group. 1990. Discovery and significance of the
Takikawa sea cow (Hydrodamalis spissa) from Numata-cho, Uryu-gun, Hokkaido, Japan.
Earth Science (Chikyu Kagaku) 44(4)(229): 224-228. [In Japanese.]
Gannon, F. 1990. The last of the manatees? Philip Morris Mag. 5(5): 22-25. Nov.-Dec.
Gingerich, P.D., D.E. Russell, and N.A. Wells. 1990. Astragalus of Anthracobune
(Mammalia, Proboscidea) from the Early- Middle Eocene of Kashmir. Contrib. Mus.
Paleo. Univ. Michigan 28(3): 71-77. [Discusses relationships of early proboscideans to
desmostylians and sirenians.]
Ivany, L.C., R.W. Portell, and D.S. Jones. 1990. Animal-plant relationships and
paleobiogeography of an Eocene seagrass community from Florida. Palaios 5: 244-258.
[Reprinted in Florida Paleo. Soc. Newsletter 8(1), 1991.]
Kiely, J. 1991. A million years in the making. American Way 24(3): 16, 18, 20, 22, 27.
[Popular account of Florida manatees.]
Klishin, V.O., R. Pezo Diaz, V.V. Popov, and A.Ya. Supin. 1990. Some characteristics of
hearing of the Brazilian manatee, Trichechus inunguis. Aquatic Mammals 16(3): 139-144.
Lefebvre, L.W., and J.A. Powell, Jr. 1990. Manatee grazing impacts on seagrasses in
Hobe Sound and Jupiter Sound in southeast Florida during the winter of 1988-89. U.
S. National Technical Information Service Document No. PB90- 271883: vi + 36.
Mann de Toledo, P. 1989. Sobre novos achados de sirenios (Sirenotherium pirabense
Paula Couto, 1967) na Formac,ao Pirabas (Para', Brasil). Bol. Museu Paraense Emilio
Goeldi, Ser. Ciencias da Terra 1(1): 5-10. [English summary.]
Marmontel, M., T.J. O'Shea, and S.R. Humphrey. 1990. An evaluation of bone
growth-layer counts as an age- determination technique in Florida manatees. U.S.
National Technical Information Service Document No. PB91-103564: x + 94.
Marsh, H. 1991. Our tropical siren. Australian Geographic No. 21:
Marsh, H., and W.K. Saalfeld. 1990. The distribution and abundance of dugongs in the
Great Barrier Reef Marine Park south of Cape Bedford. Austral. Wildl. Res. 17(5): 511-524.
McClintock, J. 1990. Too nice to live. Life 13(14): 42-43, 45-48. Nov. 1990.
Mignucci Giannoni, A.A. 1990. Manatee mortality in Puerto Rico: urgent need for
assessment and preventive action. Whalewatcher 24(1): 10-12.
O'Shea, T.J., and R.L. Reep. 1990. Encephalization quotients and life-history traits in the
Sirenia. Jour. Mammal. 71(4): 534-543.
Pilleri, G. 1989. Endocranial cast of Metaxytherium (Mammalia: Sirenia) from the Miocene
of Cerro Gordo, Almeria, Spain. IN G. Pilleri (ed.), Contributions to the paleontology
of some Tethyan Cetacea and Sirenia (Mammalia) II. Ostermundigen
(Switzerland), Brain Anatomy Inst.: 103-113.
Pilleri, G., and F. Cigala Fulgosi. 1989. Additional observations on the Lower Serravallian
marine mammals [sic] fauna of Visiano and the Stirone River (northern Apennines). IN
G. Pilleri (ed.), Contributions to the paleontology of some Tethyan Cetacea and Sirenia
(Mammalia) II. Ostermundigen (Switzerland), Brain Anatomy Inst.: 63-85.
Preen, A.R. 1988. Dugongs of Arabia. Jour. Saudi Arab. Nat. Hist.
Preen, A.R. 1991. Amorous antics in Moreton Bay. Australian
[Popular account of dugong mating herds.]
Soc. 2(8): 43-48.
Geographic No. 21: 55.
G.B., J.P. Reid, and G. Carowan. 1990. Distribution and movement patterns of
(Trichechus manatus) in northwestern peninsular Florida. Florida Marine
Publs. No. 48: 1-33.
Reynolds, J.E., III, and K.D. Haddad (eds.). 1990. Report of the Workshop on Geographic
Information Systems as an Aid to Managing Habitat for West Indian Manatees in Florida
and Georgia. Florida Marine Research Publs. No. 49: 1-57.
Sibbald, J.H. 1990. The manatee. Minneapolis, Dillon Press, Inc.
Animals Books): 1-60. [Children's book; list price $12.95.]
Suraru, N., and V. Codrea. 1988. [A sirenian premolar (right lower P4) in the Grobkalke
horizon at Cluj-Napoca.] Crisia 18: 689-695. [In Rumanian; French summ.]
Tate, S. 1990. Mary Manatee: a tale of sea cows. Nags Head (North Carolina), Nags Head
Art (Suzanne Tate's Tell-Tale Nature Series, No. 7): 1-28. [Book for young children; list
CHANGES OF ADDRESS
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S.W. 2000, AUSTRALIA
Exchange, Sydney, N.
Dr. Robert L. Brownell, Jr., U.S. Fish & Wildlife Service, National Museum of Natural
History, Room 378, Smithsonian Institution, Washington, D.C. 20560, USA
Luz del Carmen Colmenero R., BIOSILVA, A.C., Apartado Postal 403,
Quintana Roo, MEXICO
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