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Sirenews (ISSN 1017-3439) appears twice a year
Sirenews (ISSN 1017-3439) appears twice a year
in April and October and is edited by Daryl P. Domning,
Department of Anatomy, Howard University, Washington, D.C. 20059 USA
(fax: 202-265-7055). It is supported by the U.S. Marine Mammal Commission.
NUMBER 21 APRIL 1994
IN THIS ISSUE: REPORTS OF KINGSTON AND
GAINESVILLE WORKSHOPS (pp. 3-4)
UPCOMING MANATEE GIS
WORKING GROUP MEETING (p. 5)
SHARK BAY DUGONG
RESEARCH NEEDS (p. 9)
EDITORIAL: TEN YEARS OF SIRENEWS !
With this issue, Sirenews begins its second decade. This is a testimony to the loyalty of its
readers, without whose contributions and continuing interest this newsletter would long ago
have ceased to exist. It is also tangible evidence of the flourishing state of sirenian research
and conservation efforts throughout the world. This growing human attention to the status and
needs of manatees and dugongs encourages me to believe that these species will survive the
current mass extinction after all. So, my sincerest thanks to all of you who have helped make
this publishing project a success, as well as a continuing source of pleasure for its editor.
This anniversary also coincides with several other significant milestones for the sirenian
research and conservation community. A workshop on manatee conservation held last month in
Jamaica (see report below) inaugurated what we hope will be a new era of activity in the wider
Caribbean region; and Sirenews stands ready to serve as a medium of communication for the
regional network that is to grow out of that meeting. A few days later, the First International
Manatee and Dugong Research Conference took place in Gainesville, and was hailed as a great
success by its surprisingly numerous participants. This will be followed in June by the first
meeting of the new Manatee Geographic Information System Working Group in Florida yet
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another sign of the increasingly sophisticated technology being brought to bear on sirenian
problems. It appears that our specialty is on the point of crystallizing on a global scale in a
way few would have anticipated ten years ago.
This is therefore an opportune moment for a synthesis of what sirenologists up to this
time have achieved; so it is fitting that this month has also seen my sirenian bibliography go to
press. Embracing literature from 1507 to 1994, and probably more exhaustive in coverage than
the information-retrieval apparatus available for any other group of organisms, it is intended to
be a foundation on which future workers can build with greater ease and assurance than ever
before. With a sure grip on the data of the past, growing use of the data-processing tools of the
present, and the achievement of a critical mass of active workers, sirenology can now look
forward to a bright future of discovery.
The moment is also convenient to review, for the benefit of our many new readers,
some of the basic facts about Sirenews itself. This newsletter is intended as an informal forum
for communication within the sirenian research and conservation community, and reaches a
select readership of about 200 individuals and organizations worldwide. Since it is not
designed as a mass-circulation publication, I have not attempted to advertise its existence to the
general public or greatly expand its mailing list, nor do I wish to (more on that in a moment).
However, I am happy to send it gratis to anyone with a serious interest and involvement in
sirenian affairs.
This constraint on circulation arises partly from Sirenews' nature as the official newsletter
of the Sirenia Specialist Group (though it is by no means restricted to SSG members), but more
practically from the logistics of its publication. This is entirely a one-man operation; your
Editor has absolutely no secretarial or other help with its compilation or mailing. He
maintains the mailing list; types the newsletter from your submissions, down to the last
keystroke; prepares camera-ready copy and delivers it by hand to the printer; addresses, stuffs,
and affixes postage to all the envelopes; and hauls them to the post office all as a part-time
job in addition to full-time research, academic, and other duties. Hence his reluctance to see
the number of such envelopes grow too large! A corollary of this is that if you no longer
wish to receive Sirenews, it would be much appreciated if you would let him know so that
printing, postage, and labor expenditures can be held down.
These constraints on your Editor's time also mean that he cannot regularly contact you to
solicit news items, or indulge much in investigative journalism. If you have sirenological news,
or a provocative opinion to share, or know of past or future happenings that might be of interest
to your colleagues, PLEASE do not wait for an invitation; send it in! Otherwise it may well slip
through the cracks. This applies especially to meetings or workshops that should be reported on
in these pages; if you're a convener or just a participant, and are unsure whether someone is
covering the event for Sirenews, contact me I'll probably be happy to accept your offer to write
a report!
In all cases, please try to adhere to the copy deadlines stated at the end of each issue.
They never change April 1 and October 1 of every year and I do try to stick to them. If
Sirenews (ISSN 1017-3439) appears twice a year
your piece arrives after the newsletter gets put to bed (and some have), it's six months to the
next issue and your news may be pretty stale by then! If your submission is a long one (more
than a page), please consider submitting it on MS-DOS diskette preferably 5-1/4" in WordStar
or ASCII format.
To quote a reminder from our very first issue: Sirenews is "an informal forum, not to be
considered citable, formally-published literature; it will not be 'peer-reviewed', and contributions
to it should not be quoted without the written permission of the author. Certainly the opinions
expressed will be those of the writers and not necessarily those of IUCN or other
organizations. Therefore, I hope that contributors will feel free to offer informal speculations
and ideas as well as news in the interest of rapid communication." For some time the Zoological
Record has been indexing items from this newsletter, and I have noticed some people citing
information from Sirenews in their publications. This is NOT a practice to be recommended,
however; and articles from Sirenews will not be listed in my forthcoming sirenian
bibliography. As is also true of theses, abstracts, in-house reports, and all other forms of "gray
literature", if it's important enough to cite, it's important enough to publish through the normal,
peer-reviewed outlets. Quality scholarship demands no less, and we need to set a good example
for our students.
One further note to our subscribers, in response to many inquiries: back issues of
Sirenews are in most cases not available. To avoid tying up money in inventory, print runs are
kept to a size commensurate with the current mailing list. I have a very few copies of some of the
more recent issues, which I am happy to distribute as long as they last, with priority going to
requests from libraries. However, complete runs of back issues cannot be had, nor are there any
plans to reprint them, nor am I in a position to duplicate them to order for individuals; so I'm
afraid you'll have to borrow copies and xerox them yourselves.
This little newsletter's second decade will take us into the next century. Centuries to
come will look back on our era as the time of crisis, when the long-term survival of sirenians
and countless other species was decided one way or the other. If they make it past the next
hundred years of human population growth, they can probably survive anything, even asteroid
impacts. As news of your efforts keeps coming in, I look forward to seeing how the story
unfolds. DPD
REPORT OF CARIBBEAN MANATEE WORKSHOP
On 1-4 March 1994 the Regional Workshop on the Conservation of the West Indian
Manatee was convened in Kingston, Jamaica by the Natural Resources Conservation Authority
(NRCA) of the Government of Jamaica and UNEP's Regional Coordinating Unit (RCU) of the
Caribbean Environment Programme, with partial financial support from the Government of the
United States of America.
The objectives of the meeting were to review and exchange information on the status of the
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West Indian manatee, Trichechus manatus; review and provide inputs to the draft regional
management plan for the West Indian manatee; and formulate a specific plan of action of
priority conservation activities to be implemented during the 1994-95 biennium. Twenty-one
experts from the region, as well as ten observers representing non-governmental organizations
and academic institutions, participated in the meeting. Regional experts present included,
among others, Dr. John Reynolds, Chairman of the U.S. Marine Mammal Commission; Dr.
Daryl Domning, sirenian specialist; Dr. Daniel Odell, Research Biologist at Sea World; Dr.
Thomas Carr of the Caribbean Conservation Corporation; Dr. Miriam Marmontel, manatee
researcher from Brazil; and Mr. Benjamin Morales, manatee researcher from Mexico. Other
experts representing ten of the nineteen manatee-range countries of the region also participated
in the meeting.
The meeting successfully reviewed the draft regional management plan and provided
technical inputs to assist with its finalization. The draft plan contains general information on
the biology and distribution of the species in the region, as well as specific information on its
status in each of the nineteen manatee-range countries. However, the main component of the
draft plan is a general framework for manatee conservation in the Wider Caribbean, which
includes recommended priority, as well as long-term regional activities. The draft plan also
recommends specific in-country activities to be implemented at the national level.
The meeting agreed on the following priority activities as part of the draft plan:
environmental education and public awareness; assessment of manatee status and distribution
in those countries which have not done so; increased protection for manatees and their habitat
and reduction of human-related mortality through adoption of international treaties and
enforcement of national legislation; preparation of national recovery plans by national recovery
teams; establishment of a regional cooperation and information network for manatee
conservation with the assistance of a regional network coordinator. Many of these
recommended activities follow the model of the successful sea turtle conservation effort of
WIDECAST, which has been implemented in the region for the last ten years in cooperation
with UNEP.
The meeting also recommended that the draft plan include, as an additional appendix,
sample formats for data-gathering relevant to manatee conservation in order to ensure
uniformity in the type of data collected in the region.
Prior to the finalization and approval at the intergovernmental level of the draft
management plan, it will be circulated among the manatee-range countries not represented at
the meeting to ensure that the information is accurate and relevant.
In keeping with these recommended priority activities, the meeting identified three
main activities to be implemented during 1994-95: 1) the production and wide dissemination in
English, Spanish, French, and Dutch of educational materials (pamphlets, posters, and videos)
using as much as possible existing materials from relevant organizations and programs; 2)
support of an ongoing manatee conservation effort between Mexico and Belize to assist with
the development of the relevant recovery plans and school-system educational activities; and 3)
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development of national recovery plans and national recovery teams for those manatee-range
countries that have already begun relevant manatee conservation activities.
Additionally, the meeting recommended that, in keeping with the WIDECAST model
and pending intergovernmental approval of the draft management plan, an interim regional
manatee coordinator and an interim informal manatee advisory group assist the Secretariat with
the preparation of the national recovery plans and implementation of the other recommended
activities as appropriate. [ED. NOTE: Dr. Miriam Marmontel was unanimously recommended for
the role of interim regional manatee coordinator.]
Additional recommendations requested the States of the Wider Caribbean to accede to or
ratify the SPAW Protocol, as well as the CITES, Ramsar, CMS, and Biodiversity
Conventions, as these relate to the conservation of endangered species. It was also
recommended that the Secretariat establish closer cooperation with the Secretariats of the
treaties mentioned above, as well as with relevant programs of the Marine Mammal Action
Plan.
For further information, contact: UNEP Caribbean Environment Programme, Regional
Coordinating Unit, 14-20 Port Royal Street, Kingston, Jamaica; telephone: (809) 922-9267 to 9;
fax: (809) 922-9292; Telex: 3672 UNEPCARJA; Email: UNIENET:UNX040 &
ECONET:UNEPRCUJA. Alessandra Vanzella Khouri (Programme Officer, UNEP-
CAR/RCU)
MANATEE CONFERENCE EXPRESSES CONCERN ABOUT
HABITAT LOSS IN COASTAL ZONE
The First International Manatee and Dugong Research Conference, held in Gainesville,
Florida, on March 11-13, 1994, brought together over 200 scientists from 17 countries who
are involved in conservation and research projects on manatees and dugongs. This diverse
group of experts presented new information on sirenian evolution and genetics, monitoring of
sirenian distribution and trends in abundance, manatee immunology, anatomy and behavior,
manatee hearing and response to approaching boats, management challenges, and the impact of
coastal zone degradation on sirenians throughout their range. In many of the 65 countries
where sirenians still occur, gillnetting, deforestation, and poor agricultural practices have
contributed to declining quality and diversity in coastal marine systems. Seagrass losses have
been documented on both coasts of Florida and in Australia, and there is growing concern in
countries such as Mexico and Belize that nearshore plant and animal communities will
disappear as human populations and coastal development expand. The potential for conflicting
objectives in freshwater aquatic plant management was also highlighted. Aquatic plant
managers and manatee biologists must work together to ensure that plant control does not have
detrimental effects on manatees.
The conference, sponsored chiefly by the University of Florida's College of Veterinary
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Medicine, was immediately followed (on 14-18 March) by a workshop on manatee and dugong
research methods for participants from developing countries. This Sirenian Research
Workshop was sponsored by the National Biological Survey's Sirenia Project. Its purpose was to
train biologists, primarily from the Caribbean region, in methods of sirenian research, such as
aerial surveys, capture techniques, food habits analysis, and radiotelemetry. This training was
completed at the Florida Department of Environmental Protection's Marine Research
Institute in St. Petersburg, and at Sea World in Orlando. Twenty-three biologists from 12
countries participated in the workshop.
On the last day of the workshop, the participants divided into groups to assess the
applicability of the various techniques used to study sirenians. The chart on the following
pages presents the results of this assessment as summarized by Helene Marsh.
The conference and workshop emphasized the need for coordinating our efforts to study
and protect manatees across international boundaries, and laid the foundation for transferring
knowledge and technology developed for the Florida manatee to sirenian researchers
worldwide. The importance of sirenians as flagship species for the coastal marine environment
was widely recognized.
For a copy of the conference proceedings (= book of abstracts), send US$5.00 to:
Office of Conferences and Institutes, Institute of Food and Agricultural Sciences, University of
Florida, P.O. Box 110750, Gainesville, FL 32611-0750. Lynn Lefebvre and Roger Reep
MANATEE GIS WORKING GROUP MEETING
The first meeting of the Manatee GIS Working Group will take place June 29, 1994, at the
University of South Florida, St. Petersburg. The purpose of the Working Group is to
encourage communication among organizations interested in cooperating on the Manatee
Geographic Information System (MGIS) by presenting a forum where individuals can gain
access to expertise, examine computer hardware needs, and discuss data-sharing issues. The
specific goal of the upcoming meeting is to produce a Marine Mammal GIS Users Reference
Guide, which will be a set of guidelines that cooperators can follow to effectively interact with
the MGIS. Ultimately, the Working Group will serve as a forum for discussing database
management issues, examining analysis techniques, and evaluating resource-use options
impacting manatees.
The groundwork for the upcoming Working Group meeting was laid by the GIS
Coordinating Team. This team has met semi-annually for two years and includes
representatives from the Marine Mammal Commission and Federal, State, and County
government agencies.
If you are interested in participating in the Manatee GIS Working Group, please RSVP by
the end of April, if possible, so that we can send out an information packet and make the
necessary arrangements. We want to emphasize that the MGIS Working Group belongs to the
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participants and is open to governmental and non-governmental organizations alike.
Participants are expected to contribute to the development of the MGIS and follow the
guidelines that the group establishes. Success of the Working Group will depend on the user
community's commitment to make it function effectively.
Please contact:
Richard Flamm
Chairman, MGIS Working Group
Florida Marine Research Institute
100 8th Avenue SE, St. Petersburg, FL 33701-5095
tel: (813)-896-8626, ext. 255
fax: (813)-823-0166
internet: richard@manatee.fmri.usf. edu
DEP email: flamm r
The tentative agenda for the meeting is given on p. 8 below.
The Manatee GIS Working Group: First Meeting
Tentative Agenda
St. Petersburg, FL, June 29, 1994
University of South Florida, St. Petersburg, Activities Center
Comer of 2nd St. South and 6th Ave. South
Expected Participants
State agencies
Non-governmental organizations: Save the Manatee Club, business community, County
representatives
Federal agencies
Conservation organizations
Universities
Contractors developing data for Manatee GIS participants
Opening remarks (9:00 AM, R. Flamm)
Historical overview (9:10 AM, J. Reynolds)
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Roles of participating agencies in developing Manatee GIS (9:30 AM)
Marine Mammal Commision (J. Reynolds)
Department of Environmental Protection-Research (B. Weigle)
Department of Environmental Protection-OPSM (P. Rose or K. Frohlich)
National Biological Survey, Sirenia Project (L. Lefebvre)
County government (Dade or Brevard counties)
U.S. Fish and Wildlife Service (B. Turner or J. Kraus)
Break (10:45 AM)
Manatees and their ecosystem: data requirements (11:15 AM, R. Flamm)
Manatee data themes (11:30)
Mortality (S. Wright)
Aerial Survey (L. Ward)
Telemetry (B. Weigle)
Boating Studies (K. Frohlich)
Other: seagrass, bathymetry (C. Friel)
Lunch (1:00 PM 2:15 PM)
Data exchange (2:15 PM, C. Friel)
Data standardization, documentation, and ethics issues
Manatee GIS reference guide: an approach to resolving the above
Future vision (3:00 PM)
Standard paper map series (B. Porter)
Manatee atlas on CD-ROM (B. Weigle)
Integrated modeling and decision making (R. Flamm)
Conclusion and discussion (4:00 PM, R. Flamm)
MANAGEMENT OF THE SHARK BAY DUGONG POPULATION:
RESEARCH REQUIREMENTS
The dugong population at Shark Bay, Western Australia, estimated to include
approximately 10,000 individuals of all ages, may represent 10-12% of surviving dugongs. It is
one of the largest known, and the only one of its size that can be attributed to a relatively
discrete and apparently isolated area. In the context of World Heritage listing for the Bay, and
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the establishment of the Shark Bay Marine Park, There is both an opportunity and a
requirement for research essential to a well-founded management program.
Information gathered between 1974 and 1992 provides a substantial basis for further
study and for management, but is incomplete in many areas. As I don't anticipate further
research at the Bay in the near term (the next 4-5 years), I've outlined what I see as pressing
needs for further study, hoping that my suggestions can be followed up when opportunities
arise.
I. Habitat Use
A. Forage resources:
The full extent of the Halophila spinulosa bed discovered in 1992, and the seasonal
persistence (or lack of it) of the high standing-crop biomass observed, need to be determined.
The information could be readily obtained using the techniques applied in 1992 (Anderson,
submitted to Wildlife Research). The bed is likely to be highly vulnerable to trawling
operations and to have importance for the productivity of the Bay ecosystem as a whole. The
degree of activity and impact of trawlers in northern Herald Bight should be investigated.
B. Summer distribution of dugong activity:
A summer survey, like that carried out in July 1989, is essential for an effective
understanding of the habitat requirements of the Shark Bay dugong population. Although
winds make summer survey work difficult to schedule, a comprehensive survey is not
impossible. Ideally, two surveys (March and October) should be flown to bracket the summer
season. Surveys at these times would avoid the windiest months.
C. Movements:
Seasonal distribution of dugong concentrations clearly varies from year to year under
influence of temperature (influenced by weather and probably the Leeuwin Current). The 1989
discovery of large numbers of dugongs using the area N and E of Cape Peron raised the
question of whether seasonal migration patterns may be separate on eastern and western sides
of the Bay, or whether there is a single population that may vary in distribution from year to
year. The question could be economically attacked through both photoidentification and a
program of aerial spot surveys at selected localities over several years.
II. Reproductive Biology
A. Breeding season:
Our information on breeding seasons at Shark Bay is very limited. The lek at Gladstone
runs from September through January (my paper on the lek should be submitted to Behavior in
January 1994). A dead neonate was found at Monkey Mia in November. Neonates appear as
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late as March at Gladstone. At present, except by extrapolation from Queensland where
breeding (August or September through December or January) is associated with a very
different wet/dry season cycle, we have very little understanding of when dugongs at Shark
Bay mate and give birth. Further information on the timing of mating is vital to any
management program.
B. Mating:
The lek at Gladstone can account for only a small portion of annual matings. Are there
other lek sites? Does the number of females visiting the lek vary from year to year? Do mating
herds (as postulated in Queensland) occur in Shark Bay? My work on the Gladstone lek only
scratches the surface of what might be done there, provided the site is properly protected from
intrusive research, ecotourism, or documentary filming. It is possible that the site and
associated behaviors are unique! If so, the site is of very high scientific value and further
intensive (and non-intrusive) study is justified for scientific reasons alone.
C. Calving:
It is a reasonable assumption that dugongs are most vulnerable to predation at birth and in
the first few weeks of life. Although I expect that calving will prove to be spatially and
temporally dispersed, the rarity of observations suggests that there must be favored calving
sites that are presently not visited by humans. It should be a management priority to discover
when and where most calves are born and take appropriate measures for protection before
unforeseen developments interfere.
III. Social Structure
A. Group composition:
My observations on scarring patterns suggested that adult males may be solitary, and
that herds may consist of adult females and immatures of both sexes. If this is actually the
case, it has implications for management. The issue could probably be resolved by an extended
photoidentification study.
B. Group size:
May vary with season and location. As ecotourism develops, a compulsory system for
recording locations of sightings, estimates of numbers, and proportion of cow-calf pairs should be
instituted to provide information for management purposes.
IV. Response to Disturbance
A. In a situation where recreational boat traffic and ecotourism can be expected to
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grow, dugongs may be subject to increasing harassment. A program in which observers were
posted on tour boats, to monitor tour boat activity and to record dugong responses, should be set
up to establish a basis for management regulations.
B. There have been proposals in the past (e.g., sand mining, establishment of artificial
shelters for rock lobsters in seagrass beds) that could impact the dugong population. Other
proposals for commercial exploitation of the Bay are likely in the future. Data gathered on all
aspects of dugong biology in the Bay should be assembled in data bases designed to be readily
accessible in the event of both anticipated and unanticipated development proposals.
C. As early as 1988 I was promised that consideration would be given to establishment of
a dugong sanctuary encompassing both the northern and the southern coves at Gladstone. To my
knowledge nothing has been done. This is basically a people-management problem, and
implementation requires some focused research on human use of the Gladstone area, and on
alternative sites that could meet human demands while adequately protecting lek and foraging
areas in and near the Gladstone embayment. Paul K. Anderson
LOCAL NEWS
CUBA
Recent Activities. Lourdes Ferrer
reports that she and Alberto Estrada have
presented papers on manatees at two recent
meetings in Cuba:
- "The manatee as a possible tourist
attraction in Cuba" by L. T. Ferrer, at the
International Workshop on Ecotourism,
held in Santiago de Cuba, 22-25 Nov. 1993.
- "Aerial censuses of the Antillean manatee
in the Zapata Peninsula" by L. T. Ferrer and
A. R. Estrada, at a meeting on Tropical
Ecology held in Havana, 6-10 Dec. 1993.
They are also revising for publication
their summary paper on manatee distribution
in Cuba.
In March 1994, Miriam Marmontel
came to see them in her new capacity of
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interim regional manatee coordinator (see
Report of Caribbean Manatee Workshop,
above). They found her visit very
stimulating, and we look forward with
pleasure to increased Cuban participation
in the new regional efforts to protect
manatees.
FLORIDA
Florida Manatees Are Still
Endangered. Manatees in Florida have
been granted protection for almost a century,
but the population is still considered in danger
of extinction because of excessive mortality
and habitat limitations. During a statewide
aerial survey in 1992, fewer than 2,000
manatees were sighted. In order to guide
species recovery, a recovery plan was
developed in 1980 and revised in 1989 and
1994. One of the major research objectives of
the plan is to better understand manatee
population biology.
As a graduate student at the University
of Florida, I analyzed data and material
collected during a 16-year period by a team
of federal, state, and non-government
agencies involved in manatee research. The
existence of over 1,200 skulls of manatees
recovered dead from Florida's waterways
allowed me to develop a technique to
estimate age from bones. These data were
then coupled with information derived during
necropsies of most of those specimens,
yielding information on age-related aspects
of mortality and reproduction for the Florida
manatee population.
Collision with boats is the most
prominent identifiable cause of death among
manatees, affecting all ages indiscriminately.
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Mortality takes a larger toll on younger
manatees, as it does in most mammals. Once
manatees reach maturity, the rate of mortality
decreases considerably and remains constant
throughout the rest of life. Adult survival is
considered high, on the order of 90%, a
value comparable to other marine mammals.
Manatees may mature at 4 years of age, but
females produce only one calf roughly every
3 years. With such low reproductive
capacity, they could not persist without
extreme longevity of adults. Indeed,
manatees may live up to and beyond 50 years
of age.
Because of manatees' longevity and
low reproductive rate, it is very difficult to
detect population changes quickly enough to
implement corrective management actions.
For that reason I conducted a population
viability analysis through computer
simulations. Modelling allows a range of
manipulations of population parameters in a
way that would not be possible in the wild,
given the manatee's level of
endangerment. The simulations do not
predict with certainty what will happen to
the Florida manatee, but project the most
likely outcome for the population under
the parameters provided. Modelling also
identified fecundity and mortality
(especially adult mortality) as the factors
that contribute most to the population's
growth or decline.
A scenario with an initial population
size of 2,000 and population parameters
calculated from the 16 years of data resulted
in a gradually declining population, a
probability of persistence of 44% in 1,000
years, and a mean final population size
equivalent to only 10% of the original
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value (or about 200). A chance of
persistence of less than 50% in 1,000 years
is very low for a large mammal like the
manatee, and such a negligible final
population size will certainly not guarantee
the necessary levels of genetic variability
for maintenance of the population.
When adult mortality was reduced by
10% in the model, population growth
improved considerably, but when adult
mortality was increased by 10% the
population quickly dwindled. Only under
constant conditions, absence of catastrophes,
or very large population sizes did the
manatee population show high chances of
surviving in the long term.
It is important here to make a
distinction between short-term viability in
face of normal events, and adaptability or
long-term survival. A problem associated with
trying to save endangered species is that
people often find it difficult to plan beyond
a human's lifespan. Although 1,000 years
may seem like a long time, it is in fact very
short in ecological terms. Manatees have
inhabited Florida's waters for millions of
years. It would be a shame if the human
race could only plan for manatee survival
for the next few decades.
Results from my study indicate that
the Florida manatee population is still at high
risk of extinction in the long term. What
seems clear is that any variability in the
population parameters, any additional stress,
or a catastrophe might tip the balance
towards a greater risk of extinction.
Man can improve the prospects of the
manatee population by preventing loss of
habitat, allowing free manatee movements
along traditional travel routes, and increasing
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the network of sanctuaries and refuges.
Manatees are able to respond to their
environment and exhibit considerable
flexibility in adjusting to local long- and
short-term habitat conditions. If habitat is
protected, especially in areas important for
manatee reproduction and feeding, and
mortality levels are reduced, the species can
be recovered. However, given the high
incidence of boat-related mortality and
rapid growth in boat traffic and coastal
development, the prognosis is not good. Man
can dramatically alter natural processes of
habitats, and habitat alteration is likely to
become even more significant in the future.
The goal of the Florida Manatee
Recovery Plan is to downlist the species from
endangered to threatened. Florida and Georgia
probably contain the largest population of
West Indian manatees. In all other parts of its
range throughout the Caribbean and northern
South America, the species is faced with
threats of habitat alteration and local hunting.
Manatees in the southeastern United States
have the best chance of persisting into the
future, but their protection and preservation
will continue to require political decisions
and public awareness and support. -
Miriam Marmontel (for the Save the
Manatee Club)
U.S. Fish and Wildlife Service
Reorganization. The Sirenia Project based
in Gainesville, Florida is officially no longer a
part of the U.S. Fish and Wildlife Service,
having been incorporated into the new
National Biological Survey. In other
respects, however, it remains unaltered,
still doing business at the same address
(412 NE 16th Ave., Room 250,
Sirenews (ISSN 1017-3439) appears twice a year
Gainesville, FL 32601) under the capable
leadership of Dr. Lynn Lefebvre.
West Coast Manatee Telemetry
Study. The Florida Department of
Environmental Protection (DEP) is
currently tracking 12 manatees in Tampa
Bay and along the west coast of Florida
through VHF and satellite telemetry. Six of
these manatees were tagged during a winter
capture held at the Tampa Electric
Company's Big Bend power plant in Apollo
Beach on January 31-February 2, 1994. Since
the project's initiation in February 1991, the
DEP has tagged 37 manatees. The
information gathered by this project
includes habitat utilization, animal
associations, age and sex differences in
movement patterns, climatic effects on
behavior, and life history parameters.
Prior to attaching the tags,
measurements are taken on each animal,
blood samples are collected, and blubber
measurements and scar photographs are
taken. In addition, two passive integrated
transponder (PIT) tags are implanted in each
animal, in the upper head region, between the
skin and blubber layers. These tags,
slightly larger than a grain of rice, provide
long-term identification of individual
animals. Recently, a manatee that had PIT
tags and a radiotransmitter was recovered
dead. The carcass was very decomposed, but
the PIT tags were still present and functional.
If the radiotransmitter had not been recovered
with the animal, the animal would still
have been identified through the PIT tags
even though no other marks were
recognizable. Beth Wright
Sirenews (ISSN 1017-3439) appears twice a year
INDONESIA
Cafeteria Experiment with Captive
Dugong in Surabaya Zoo. Within the
framework of the Dugong Management and
Conservation Project, a so-called "cafeteria
experiment" was carried out during 1993
with a captive dugong in Surabaya Zoo. This
experiment was similar to the "salad-bar
experiment" performed with captive manatees
by Wanda Jones at Homosassa Springs
(Florida) during 1993-94, and a comparison
of both studies may reveal some interesting
features of sirenian feeding ecology.
The aim of this test was to determine
dietary preference of the dugong for a range
of seagrasses. The dugong, a female with a
total length of 2.70 m, had been caught in
1975 in Teluk Graganan, southeast Java, and
had been kept in good health since in a
reservoir of 60 m3. The reservoir was
refreshed weekly with a truckload of seawater
obtained from the Strait of Madura, some 30
km from the zoo. The dugong had been fed
daily at 8:00 A.M. with approximately 50 kg
of fresh Syringodium isoetifolium leaves,
which were
transported to the zoo by truck over 300 km
from Muncar on the south coast of Java. The
main reason for feeding Syringodium leaves
was the fact that they float after being cut and
thus are easily collected. During a field trip
to Muncar, we observed five fishermen who
collected 250 kg fresh weight of Syringodium
leaves in less than 2 hours.
A first analysis of the data obtained
indicated a preference of the dugong for
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seagrasses in sequence, from high to low
preference, as follows: 1) Halodule
uninervis, 2) Halophila ovalis, 3)
Cymodocea rotundata, 4) Syringodium
isoetifolium, 5) Thalassia hemprichii. The
observed preference for Halodule and
Halophila confirms findings of Marsh (1982),
Preen (1993), and Lanyon (1993) on free-
ranging dugongs.
Measurements and observations of the
dugong in Surabaya Zoo indicated that the
animal showed no stunted growth and
appeared to be in good health. The animal
was well taken care of by the Management
of Surabaya Zoo and is one of the few
dugongs kept successfully in captivity.
Another dugong, originating from the
Philippines, has
been kept in good condition in the Toba
Oceanarium (Japan), while being fed with
Zostera marina.
Earlier investigations of two captive
dugongs in the Ancol Oceanarium in Jakarta,
which died in 1992, clearly showed stunted
growth of these animals, which was probably
due to the small size of the reservoir in which
they were kept. Based on this observation, it
seems important to develop guidelines for
captive conditions for dugongs. Hans de
longh
THAILAND
Tame Dugong. Since October
1993, a young male dugong has been seen
repeatedly at Had Chao Mai National Park in
Thailand's southern Trang Province.
Fishermen at Chao Mai village said that
this dugong initially became trapped in a tide
pool and that the children of Chao Mai took
Sirenews (ISSN 1017-3439) appears twice a year
pity on it and towed it back to the open
water. But the dugong became trapped in the
same tide pool two more times. After a
while he became used to humans and seems
to enjoy their presence, especially that of
children.
Now, when the tide goes down,
whoever wishes to see this playful dugong
may do so. One needs only to enter the tide
pool, about 60 cm in depth, and slap his hand
on the surface of the water to call him. He is
very amiable, and doesn't mind being
handled. A staff member of the Fisheries
Department said that this dugong may be
the same one that was released last year
after becoming stranded.
We are not sure why this young male
has taken such a liking to humans. I am
investigating dugongs in the area and would
be interested to know whether there are
recorded cases of dugongs or manatees in
other areas of the world that have exhibited
similar behavior. My colleagues and I will be
conducting a census of the population in the
Had Chao Mai area again this year, using
aerial surveys. Suwan Pitaksintorn
(Marine National Parks Division, Royal
Forest Dept., Phaholyothin Road,
Chatuchak, Bangkok 10900, Thailand)
WASHINGTON, D.C.
Progress on Publication of Sirenian
Bibliography. The digitized manuscript of
Domning's Bibliography and Index of the
Sirenia and Desmostylia was delivered to the
Smithsonian Institution Press on 12 April
1994. It will form contribution no. 80 in the
series Smithsonian Contributions to
Paleobiology. A publication date has not yet
Sirenews (ISSN 1017-3439) appears twice a year
been set, but will hopefully be before the
end of 1994. Instructions for obtaining
copies will be included in the next
Sirenews. Possible on-line and/or CD-ROM
availability in the more distant future is also
being contemplated. DPD
ABSTRACTS
Estimate of the Distribution and Population Size of the Manatee Trichechus nianatus
(Trichechidae-Sirenia) in Guatemala (Ester Quintana Rizzo). The manatee (Trichechus
nianatis) has been listed since 1975 as an endangered species by CITES, and since 1982 as
Vulnerable in the IUCN Red Data Book. Commonly known as the West Indian manatee, it is
distributed from the southern USA through the Caribbean and along the Atlantic coast of
Central and South America as far as Brazil.
No quantitative information exists concerning the species in Guatemala. In this study
the distribution and density of manatees in Guatemala are estimated by means of the aerial
survey technique developed by authors such as Powell et al. and Rathbun et al. The various
parts of the Guatemalan Atlantic coast were overflown during four months (January, March,
April, and May). In 40 hours of surveys, a total of 73 manatees (66 adults and 7 calves) were
seen.
Based on estimates made in accord with Schaeffer et al., the manatee population in
Guatemala consists of 53 animals, with a population density of 0.401 manatees per square
kilometer. The population throughout the study area remained constant during the study, but its
its distribution within this area depended on the availability of food, shelter, warm water and
depth. The results reveal that Lago de Izabal is the most important area for the species in the
country, and it was assessed for the factors mentioned previously.
The results obtained constitute a solid basis of data concerning the needs for manatee
conservation in Guatemala, and allow for the development of a conservation and management
plan for the species in this country. [Abstract of a thesis in Biology submitted to the Universidad
de San Carlos de Guatemala in April 1993. Translated from Spanish.]
RECENT LITERATURE
Aranda-Manteca, F.J., D.P. Domning, and L.G. Barnes. 1994. A new Middle
Miocene sirenian of the genus Metaxytherium from Baja California and California:
relationships and paleobiogeographic implications. Proc. San Diego Soc. Nat. Hist. 29:
191-204.
Barriel, V., P. Darlu, and P. Tassy. 1993. A propos des conflicts entire
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phyloge'nies morphologiques et mole'culaires: deux examples emprunte's aux
mammife'res. Ann. Sci. Nat., Zool. (13)14(4): 157-171. [Engl. summ.]
Boher, S., and J. Porras. 1991. Nuevos registros del manati' (Trichechus manatus) en la
costa del Mar Caribe Venezolano. Acta Cientifica Venezolano 1991: 287.
Bruenderman, S., and K. Terwilliger. 1994. Swimming beyond boundaries: the
uncertain future of Virginia's marine mammals and turtles. Virginia Wildlife 55(1): 11-27.
Corey, D. 1990. Manatee: first book. Crystal River (Florida), Sundiver Productions Co.:
1-48. [Revised edition, 1992. ISBN 1-879488-00-0.]
Cuthbert, R. 1993. Tales from the bush: Project Mermaid. BBC Wildlife 11(11): 82.
Darling, K. 1991. Manatee: on location. New York, Lothrop, Lee & Shepard Books
(division of William Morrow & Co., Inc.): 1-48. [Children's book. ISBN 0-688-
09030-3, US$14.95.]
Domning, D.P. 1994. West Indian tuskers. Nat. Hist. 103(4): 72-73.
Domning, D.P. 1994. A phylogenetic analysis of the Sirenia. Proc. San Diego Soc. Nat.
Hist. 29: 177-189.
Domning, D.P., and J.M. Clark. 1993. Jamaican Tertiary marine Vertebrata. In: R.
M. Wright and E. Robinson (eds.), Biostratigraphy of Jamaica. Geological Society of
America Memoir 182: 413-415. [Discusses Prorastomus sirenoides.]
Dong J., Song G., and Wang G. 1992. Preliminary study on anatomy and histology of
larynx, trachea and lung of Dugong dugon. Oceanologia et Limnologia Sinica 23(4): 433-
437. [In Chinese; Engl. summ.]
Fischer, M.S. 1991. Zur Morphologie und Evolution des Geho"rorganes der
Tethytheria (Proboscidea, Sirenia). Verh. Deutsch. Zool. Ges. 84: 377.
Fischer, M.S., and P. Tassy. 1993. The interrelation between Proboscidea,
Sirenia, Hyracoidea, and Mesaxonia: the morphological evidence. In: F.S. Szalay,
M.J. Novacek, and M.C. McKenna (eds.), Mammal phylogeny. Vol. 2. Placentals.
New York, Springer-Verlag (321 pp.): 217-234.
Hellyer, P. 1993. Mammals. Tribulus: Bull. Emirates Nat. Hist. Group 3(2): 23-24.
Sirenews (ISSN 1017-3439) appears twice a year
[Reports dugong occurrences in Abu Dhabi.]
Krishna Pillai, S., J.D. Ambrose, and M. Sivadas. 1989. On an unusually large sea
cow Dugong dugon landed at Mandapam, Gulf of Mannar. Indian Counc. Agric. Res.,
Mar. Fish. Inf Serv. Tech. Ext. Ser. No. 96: 12, 16. [Hindi summ.]
McAnally, L.M. 1993. Fallacy, felony and fossils from the Sooke Formation.
Vancouver Island Paleontological Society Newsletter No. 3: 8-9. [Describes the
history of discovery of the desmostylian Cornwallius sookensis in British Columbia,
and the mysterious theft and return of the type and other specimens.]
O'Keefe, M.T. 1993. Manatees: our vanishing mermaids. Lakeland (Florida),
Larsen's Outdoor Publishing: 1-127. [ISBN 0-936513-43-8.]
O'Shea, T.J., and M.E. Ludlow. 1992. Florida manatee, Trichechus manatus latirostris.
In: S.R. Humphrey (ed.), Rare and endangered biota of Florida. Volume I. Mammals.
Gainesville, Univ. Press of Florida (xxviii + 392): 190-200.
Pickford, M. 1987. Recognition of an Early Oligocene or Late Eocene mammal fauna
from Cabinda, Angola. Rapp. Ann. Dept. Geol. Min. Mus. R. Afr. Cent. 1985-86: 89-92.
Ray, C.E., D.P. Domning, and M.C. McKenna. 1994. A new specimen of
Behemotops proteus (Mammalia: Desmostylia) from the marine Oligocene of
Washington. Proc. San Diego Soc. Nat. Hist. 29: 205-222.
Shoshani, J. 1993. Hyracoidea-Tethytheria affinity based on myological data. In: F.S.
Szalay, M.J. Novacek, & M.C. McKenna (eds.), Mammal phylogeny. Vol. 2. Placentals.
New York, Springer-Verlag: 235-256.
Sirenia Project. 1994. Atlantic Coast manatee telemetry 1986-1993 progress
report. Gainesville, Florida, National Biological Survey Sirenia Project: 2 vols. [In-
house report.]
Smith, K.N. 1993. Manatee habitat and human-related threats to seagrass in
Florida: a review. Tallahassee, Florida Dept. of Environmental Protection: i + 38.
Sutty, L. 1993. Fauna of the Caribbean: the last survivors. London & Basingstoke,
Macmillan Press Ltd. [Manatee, 20-21.]
Turner, R.O., and C.A. Buckingham. 1993. Navy is enlisted in plan to protect
Sirenews (ISSN 1017-3439) appears twice a year
manatees. Endangered Species Tech. Bull. (U.S. Fish & Wildlife Service) 18(2): 1, 10-11.
CHANGES OF ADDRESS
Chassahowitzka National Wildlife Refuge, 1502 SE Kings Bay Dr., Crystal River, FL 34429
Dr. Miriam Marmontel, Projeto Mamiraua', C.P. 0001, 69470-000 Tefe', Amazonas, BRAZIL
Dr. Helene Marsh, Dept. of Tropical Environment Studies & Geography, James Cook
University, Townsville, Queensland 4811, AUSTRALIA (fax: 61-77-815581)
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