NUMBER
IN THIS ISSUE: - MORE ON DEEP-DIVING DUGONGS (p. 3)
- NEW LIGHT ON MANATEES IN
EDITORIAL: EARTH DAY 1990
In
the very first days of 1990, the
manatee population in
This
newsletter is aimed
at specialists in
a single taxonomic group
of only four living species. On
this narrow front, the
news is sometimes encouraging,
sometimes (as above) grim; but
elsewhere there are far grimmer reverses in
progress. If estimates of destruction in the tropical rainforests are to
be believed, more species are wiped out there in a single day
than the Order Sirenia presently contains - more, perhaps, by an order of
magnitude. While working on behalf of manatees and dugongs, we must also help
whenever we can in other phases of the conflict
- especially by seizing
opportunities to raise
environmental consciousness in our respective communities and nations.
As
has often been
said in these
pages before, that consciousness needs
raising most of all on the issue
of human population growth.
Almost every nation on earth needs, but lacks, an official
population policy aimed at reducing
its present population - starting
with the United States, which
devours far more than
its fair share of the world's resources
and where political leadership
on this issue is so shamefully
lacking. Every nation must begin
forging an explicit consensus as to its
optimum population, and then set about
reaching that population level through explicit national goals (such as the
two-child or one-child family) and social policies (such as tax
incentives) designed to achieve those goals.
As
long ago as 1972, the Rockefeller
Commission concluded that it
saw no benefit from further
population growth in the
TOM O'SHEA
HONORED
FOR MANATEE RESEARCH AND CONSERVATION
EFFORTS
Dr.
Thomas J. O'Shea,
Deputy Chairperson of the Sirenia
Specialist Group, has
worked on the
This honor is a well-deserved tribute not
only to Tom but to all the current members of his team and all those who have
worked on the Sirenia
Project over the nearly two
decades of its existence. They
have been responsible for major advances in our knowledge of
sirenian biology, knowledge
which is
now being applied to
management decisions on a daily basis.
The Sirenia Specialist Group thanks them all for their past and
continuing dedication, and looks
forward to their
future discoveries. Well done,
Tom!
NEW SIRENEWS FAX NUMBER
Anyone
wishing to send communications to Sirenews by FAX is requested to
use the following
number: 202-636-5523. All communications should be clearly
addressed to "Dr. Daryl Domning, Dept.
of Anatomy"; addressing
them to "Sirenews" is not
sufficient.
LOCAL NEWS
AUSTRALIA
"Dugongs in
Deep Water". -
Notwithstanding the evidence cited by Helene Marsh (Sirenews No.
12) and the fact that many of the
sightings in the
recent Shark Bay survey
were (to my surprise) in waters with charted depths greater
than 11 m, a note of caution may be in order. Observation of feeding dives in
Shark Bay shows that
the length of the dive cycle (submerged
plus surface time) increases dramatically with depth. When depth is 2 m or less, dive cycles fall in the 45-90 second range
(including a surface time
of 1-2 s), and an individual may complete
in excess of 40 feeding dives per hour.
At depths of 11-12 m, dive cycles may
average 420 s and surface times may be
over 60 s, limiting an individual to fewer than 10
dives per hour. Moreover, animals
feeding in 11-12 m of water show what appear to be signs of stress
(resting near the surface and
breathing deeply and repeatedly between dives, "exploding" to the surface at the
end of a dive). These indications of
reduced foraging efficiency and high cost as depth increases lead me to doubt
the favorability of deep water habitat.
The proportionately longer surface time also suggests that when dugongs
do feed in deep water they may be more available to
aerial survey enumerations. This
would bias estimates of
both numbers and
habitat preference. -
Paul Anderson
Dugongs
in Deep Water: A Reply. -
The results of
recent aerial surveys suggest that deep-water seagrass meadows are a
feature of most
of the major dugong areas
in Australia. A significant
proportion of dugong sightings in the Stracke River region (>30%), Torres Strait
(>20%), Hervey Bay (>25%), and Shark Bay (>60%) have been in water
between 10 and 20 m deep. To date,
extensive deep-water seagrass meadows have been confirmed at all these
places except Shark Bay, which
needs to be investigated further. As Paul Anderson points out, the proportion
of animals which are
using these deep-water areas is unknown, as we
lack information on the relationship between diving
and surfacing times for dugongs at different depths. I have recently
applied for funds for
Tony Preen to conduct a
study entitled "The importance of deep-water seagrass meadows
to dugongs." We plan to use both
satellite tracking and time depth recorders on
dugongs in Hervey Bay. It is the
easiest of these areas to work in, and
has the most pressing management
problems as it has by far the largest level of human use. -
Helene Marsh
[EDITOR'S
NOTE: Readers may find
interesting a record of a dugong feeding
in deep water off New Ireland, Papua New
Guinea, where T. R. Williams (Cryptozoology 4: 61-68,
1986) reported surfacing "in
periods ranging from 8 to about
11 minutes" in water
40-50 feet deep. Unfortunately the lengths of times spent at the surface are not stated.]
Dugongs Sighted on Remote Offshore Reef. -
Dr. Terry Done of the Australian
Institute of Marine Science reported
sighting a dugong cow and calf
from a boat during a scientific expedition to Ashmore Reef in November 1989.
Seagrasses of the genera Thalassia and Thalassodendron occur on Ashmore Reef,
which is in Australian territorial waters about 400 km off the northern coast of
Western Australia and about 140 km from Timor.
- Helene Marsh
Traditional Hunting
by Urban Aborigines and
Islanders in Australia. - In
Australia, Dugongs are protected by
State and Federal legislation. Only indigenous people are
allowed to hunt them, and trade in dugong products is illegal.
Apart from these overall restrictions,
the situation differs somewhat in different areas. The
law is most restrictive in
Queensland, where only Aborigines and Islanders living in Trust Territories
(formerly Reserves) are automatically allowed to hunt under
State law, although they still
require a permit to hunt in the Great Barrier Reef Marine Park.
In
May 1989, four native Torres Strait Islanders with
the remains of a
dugong and a green turtle in
their boat were apprehended by fisheries patrol
officers. All the hunters are now resident
in the coastal city of Townsville near where they
had caught the dugong, and are
therefore ineligible to hunt dugongs
(or sea
turtles) without special permits.
The Islanders were charged with taking protected species.
The case has proceeded to trial, but is
currently adjourned. The hunters
explained that they procured the animals for a feast to be
celebrated in honor of their uncle who
had recently died. They maintained that it
is their tradition to
feast on dugongs
and turtles on
such occasions.
The case has also been brought before the
United Nations by the Aboriginal Development Commissioner, who said
that the
law restricting indigenous people
from hunting dugongs and turtles just because they did not live in a
Trust area was "offensive to
Aborigines and Islanders".
The situation is complicated by the
large-scale movements of Aborigines and
Islanders from their traditional lands to
cities and towns. The results of
the 1986 census of Australia indicate
that the Islander population of the Torres Strait region is about 5000, close to the estimated population at the time
of European contact. However,
the Torres Strait Islanders have
increased rapidly over the
last 25 years and have emigrated
in large numbers to the mainland
for economic reasons. Thus there are now
more than 4000 Islanders living in the
coastal cities bordering the Great
Barrier Reef Marine Park
from Cairns south.
These cities also have a combined Aboriginal population of over 9000.
The dugong population of the Great Barrier
Reef Marine Park from Cairns south is
much less than that of Torres Strait. On the basis of aerial surveys, I estimate that there
are some
12,500 dugongs in Torres Strait
(mainly in the Western Straits, which are
hunted mainly by
Islanders rather than
Papuans). This represents a
ratio of about 2.5
dugongs per Islander.
The corresponding estimate of the number of dugongs in
the Great Barrier Reef region from Cairns south is 3500,
or 0.27
dugongs per indigenous person.
The differences in the dugong numbers in
the two
areas reflects the availability
of suitable dugong habitat, and their relative importance to dugongs has
probably not changed since
European contact. Thus
we now have
the unfortunate situation of a change in the relative
numbers of potential predators
and their prey, largely as
a result of movement of the predators.
I await the outcome of the court case with
some trepidation. I fear it will be the first of several attempts to bring
the law in Queensland
more in line with those in
other states. All Aborigines and Islanders could then be allowed to
hunt dugongs, irrespective of the
conservation implications of their doing
so. - Helene Marsh
CUBA
Distribution and Status of Manatees in Cuba. - Lourdes
T. Ferrer (Centro de Investigaciones Pesqueras, Habana) and Alberto R. Estrada report that
they have completed an interview survey of manatee distribution along the
entire coastline of Cuba. A total of 293
fishermen and other persons engaged
in water-related activities reported
having seen manatees. Of the most
recent sightings by each interviewee,
58% had occurred in the 12 months immediately preceding the
interview. Sightings were concentrated
in 12
areas around the coasts of Cuba and
the Isla de la
Juventud, especially in or near
estuaries and river mouths, and
were somewhat more
frequent during the rainy
season (May to October).
An interesting aspect of the interviews
is that many interviewees believed that females with nursing young
seek safe and secluded places in estuaries, channels,
and lagoons where they can
leave their calves during the day
while they go in
search of food.
Presently the mothers return
and feed their young.
These reports have
not been verified
by direct observation; however,
a reported aerial observation of a group of calves in a river (see below) may
be significant in this regard.
Manatees were perceived
by 58% of the respondents as
having increased in numbers over the last 10 years; only 18%
thought their numbers had diminished.
Causes of manatee mortality seemed to
be primarily accidental, with
entanglement in fishing nets being the predominant cause reported.
These data are supplemented by the results
of aerial surveys undertaken in 1985-87
by Carlos Wotzkow (Museo
Nacional de Historia Natural).
Series of flights were made over two different stretches of the south coast of
Cuba, each about 90 km long: the
Ensenada de la Broa,
and the south coast of
Sancti Spiritus Province. Manatees were sighted a total of 98 times in
the course of 15.25 hours and 2415 km of
survey: 59 sightings (9.5 hours, 1425
km) in the former area and 39 (5.75 hours, 990 km) in
the latter. The maximum number sighted on any one flight was
14 in the former area and 11 in the
latter. Only two calves were seen in each area during the surveys; on another occasion, however, a group of 14 animals interpreted as juveniles was
seen by a pilot in the Rio
Hatiguanico. Although observed several
times in the lower parts of larger
rivers, manatees were never seen more
than 150 m from
the coastline, despite the presence
offshore of abundant beds
of Thalassia. Manatees are
legally protected in Cuba, populations
of sharks (potential manatee predators)
have been reduced by intensive
commercial fishing, and efforts
are made to apprehend
illegal fishermen who might take manatees; however, there
still remain threats to the
manatee population from
pollution, accidental entanglement in
nets, and deliberate poaching.
The
unconfirmed reports of
cows leaving their
calves unattended in secluded places deserve further investigation. Such
behavior has been suggested by Ed Asper
(in Reynolds, Mammalia 45: 443, 1981), but has not been confirmed for
Florida manatees either. Even if these reports prove to be illusory,
they should serve to remind us of how few observations of
wild manatees by biologists
have actually been
made. Further study
of the relatively little-known Antillean subspecies could well
reveal behavior patterns that are less common or absent in other taxa or
in other parts of the West Indian manatee's range. If the Sirenia
Specialist Group were
to select an official motto,
I would propose: "Never
underestimate a sirenian." - DPD
FLORIDA
Seagrass
Ecology and Manatee
Habitat Protection. - The National Ecology Research Center Sirenia Project
is cooperating in a study on seagrass ecology led by personnel
of the National Marine Fisheries Service, Southeast Fisheries Research Center, Beaufort, North Carolina. The Bureau of Marine
Research, Florida Department of Natural Resources, is also involved in the
project. Seagrass is an important food for manatees year-round, but is
especially relied upon during winter cold periods by
manatees aggregating at warm
water refuges on the east coast of
Florida. Hobe Sound and Jupiter Sound,
the seagrass study areas, provide
significant winter foraging sites for
manatees migrating to and from warm
water sources in southeast Florida.
The
cooperative agreement among Federal and State agencies was prompted by concern for the
degradation of water quality and a coincident
decline of seagrasses in estuaries throughout the southeastern U.S.
Florida has by far the
largest amount of tropical
and subtropical seagrasses in the
U.S. Some seagrass declines have been attributed to the adverse effects
of elevated levels of water turbidity, which reduce the amount
of light available to submerged vegetation. This study has characterized the submarine
light regime and determined the degree
of light attenuation under
various environmental conditions in Hobe Sound. Water clarity tended to be poorest in the winter and
to improve during the spring and summer.
The worst conditions occurred after the passage of Hurricane Floyd in October
of 1987. Improvement in water clarity closely tracked the increase in salinity
to normal sea water levels,
indicating that tidal flushing is a
critical aspect in maintaining
water clarity in the lagoon.
Recovery to pre-storm conditions
took about 70 days.
Preliminary estimates indicate that between 15% and
20% of the subtidal
area is vegetated by
the co-dominant seagrass species, Halodule wrightii and Syringodium filiforme, which
do not occur beyond a depth of 2
m in Hobe Sound. About two-thirds of the
lagoon's bottom is between 2 and 3 m in depth, well within the depth
limit of these seagrasses in clear
tropical waters. Submerged
seagrass in Hobe Sound usually receives 20% or more of the
incident light, indicating that
seagrass light requirements may be greater than previously estimated,
and are certainly greater than that allowed under current water quality
standards. Researchers collected data
weekly on boat traffic, wind speed, and
light attenuation in Hobe Sound
to determine the relative contributions of
boat wake-wave and wind-wave energy
to water turbidity. Vessel wake waves approximately double the
amount of wave energy in the lagoon and
could be a major source of sediment and
organic matter resuspension.
Instantaneous measurements of
the formation of turbidity plumes
following the passage of wake waves also
support this conclusion. The
removal of boat wake- induced turbidity
could result in
the conservation and enhancement of
the seagrass beds in
Hobe Sound, benefiting manatees and
many other aquatic species.
Martin County has already
made use of the study results to support an idle
speed zone for boat traffic
outside of the channel in Hobe Sound,
and two Water Management Districts are planning to extend the methods
pioneered in Hobe Sound to seagrass communities
elsewhere in Florida. - Lynn
Lefebvre and Jud Kenworthy
The
Manatee Technical Advisory Council.
- Manatee research and management efforts carried on by the State of
Florida are the responsibility of the State's Department of Natural
Resources (DNR). Ten years have now passed since the genesis of the
Manatee Technical Advisory Council,
the body officially charged with advising DNR on the conduct of its
manatee activities. A look at the history,
philosophy, and functioning
of this unique organization may be of interest in
other parts of the world where sirenian protection efforts are in progress.
The
Council was created in 1980 at
the urging of the U.S. Marine Mammal Commission (an independent watchdog
agency of the Federal Government),
and with funds provided to DNR
by the Commission. Its first meeting was held in June 1981. The
members are appointed by the Executive Director of DNR, often
on the recommendation of the Council itself, and serve without salary for
indefinite terms. At present the Council has
8 members, representing a
broad variety of backgrounds: a
member of the State House of Representatives; a
concerned citizen and spouse of a State Senator; an attorney, lobbyist, and former DNR
official; a prominent conservationist and former Assistant Secretary of the
Federal Department of the Interior; a
practicing ophthalmologist and
interested citizen; the Executive
Director of the Save the Manatee Club (a
private lobbying and fundraising organization); a biologist employed by the
Florida Power and Light Company (which
operates many of the power plants used
by manatees as warm-water winter refugia); and a sirenian biologist from an out-of-state university. DNR provides the
Council with staff support.
The
Council generally meets two to four times a year
at different locations in
Florida, which often
provides the opportunity for
field trips on which the Council members
can personally inspect sites
currently of importance to
manatee protection. The meetings
are open to the public and
typically last about half
a day. They
are routinely attended
by representatives of DNR, the
U.S. Fish and Wildlife Service, the
Florida Marine Patrol, and other agencies involved in
manatee research and/or
conservation. The agenda typically
consists of briefings by
these representatives on their agencies'
manatee-related activities since the last meeting, followed in each case by general
discussion, and often by specific recommendations in the
form of resolutions of the
Council. Formal minutes of all meetings are kept.
In
view of the Council's name, it might appear that
its actual makeup is
short on the required expertise in
manatee biology. Such an inference,
however, would be mistaken.
The issues coming before the Council are almost always administrative
or political rather than biological in
nature - a reflection of the basic
fact that it is not manatees
but people that
need managing. Therefore, the
technical expertise which the Council needs, and
has, is primarily expertise in the techniques
of environmental legislation and public administration. The
needed scientific input is readily available at Council meetings thanks to
the regular attendance of leading manatee biologists from the federal,
state, and other entities active in Florida.
In
recent years, with
the increasing shift of
manatee responsibilities from the federal to the state government, DNR's advisory council
has come to
have increasing strategic importance. However,
the attendance at
its meetings of representatives from
other agencies has
proven to have
an importance at least
equal to that
of the Council's
own deliberations. Since their
inception, Council meetings
have provided an informal but
extremely useful forum for interagency
communication and coordination. Under the auspices and scrutiny of the
Council, disagreements, friction,
and misunderstandings within and among DNR, the Fish and Wildlife Service, the Marine Patrol, the Save the Manatee Club, the Army Corps of Engineers, Florida Power
and Light, and other organizations have
been aired and resolved. In other
words, although the Council's mandate is
nominally restricted to advising DNR and
Florida's Governor and Cabinet, in
practice it has been able to
influence manatee-related affairs in a much wider arena, often merely by getting other
organizations to talk to each other.
This has contributed significantly
to the climate of
interagency cooperation and teamwork
which is the hallmark of the manatee protection effort in
Florida - in welcome contrast to
the conflicts and rivalry that too often beset work on other species
and in other places by the same and similar organizations. - DPD
WASHINGTON, D.C.
Sirenian
Bibliography Update. - The
computerization of my hand-written bibliography
and index of
the sirenian and desmostylian literature has been
completed, and all the data are now in machine-readable form. As of this writing, the database comprises 3,996
main entries (bibliographic references alphabetized by
author) and 11,921 index entries filed under a total of 1,003 different subject
headings. Over 40% of the main entries are fully indexed and annotated;
each of these is indexed under anywhere from one to as many as 124 subject
headings. Many of the
remaining main entries
are partially indexed
and annotated. The main task to be completed before
publication is the full indexing of as many of these as time
permits; emphasis here is being placed on those works most important
to the study and conservation of living sirenians. I expect to cut off this activity
arbitrarily sometime in
the early fall,
and then generate a camera-ready
hard copy for publication. Implication: If you want your latest work
included, please send me reprints as soon as humanly possible! - DPD
RECENT LITERATURE
Bay, D., and V.
Demoulin. 1989. The seagrass beds
of Hansa Bay (north coast of Papua
New Guinea). Bull. Soc. R. Bot.
Belg. 122(1): 3-17.
Buffre'nil, V. de, and D. Schoevaert. 1989. Donne'es
quantitatives et observations histologiques sur
la pachyostose du
squelette du dugong,
Dugong dugon (Mu"ller) (Sirenia, Dugongidae). Canad. J. Zool. 67:
2107-2119.
Clark, M.G.
1990. The vanishing manatee. New York, Cobblehill Books: 1-64. [Children's book.]
Coy Otero, A.
1989. A new
species of trematode of the
genus Chiorchis (Diplodiscidae), a
parasite of the
manatee Trichechus manatus
(Sirenia) in Cuba. Poeyana (Inst. Zool.
Acad. Cienc. Cuba)
No. 378: 1-4.
[In Spanish; English summary. Describes Chiorchis groschafti,
n. sp.]
Delaney, J., W. Hale, and R.
Stone. 1989. Manatees: an educator's
guide. Second Edition (revised by
M. Lamphear). Maitland,
Florida, Save the Manatee Club: 1-29.
Domning, D.P.
1989. Fossil sirenians from the Suwannee River, Florida
and Georgia. In:
G. S. Morgan
(ed.), Miocene paleontology and stratigraphy of the
Suwannee River basin of north Florida and south Georgia. Southeastern
Geol. Soc. Guidebook No. 30: 54-60.
Domning, D.P.
1989. Fossil Sirenia
of the West Atlantic and Caribbean region. II. Dioplotherium
manigaulti Cope, 1883. J. Vert.
Paleont. 9(4): 415-428.
Domning, D.P.
1989. Fossil Sirenia of the West Atlantic
and Caribbean region. III. Xenosiren yucateca, gen. et sp.
nov. J. Vert. Paleont. 9(4):
429-437.
Fernandez, S.,
and S.C. Jones. 1990. Manatee stranding on the coast of Texas. Texas Jour. Sci. 42(1):
103.
Galantsev, V.P., and D.A.
Kuz'min. 1989. Trends in development of
adaptive characters in the venous
system of hydrobiont and amphibiont mammals.
Zool. Zhur. 68(10):
107-117. [In Russian; English summary.]
Inuzuka, N.
1989. [Desmostylus and Behemotops.]
Pp. 40-76 in: Report
of Research on Ashoro Mammalian Fauna.
Ashoro Town Board of Education, Hokkaido, Japan, 201
pp. [In Japanese.]
Jacquet, A., T. Kleinschmidt,
T. Dubois, A.G. Schnek, Y. Looze, &
G. Braunitzer. 1989. The thiol proteinases from the latex of Carica
papaya L.: IV.
Proteolytic specificities of
chymopapain and papaya proteinase
determined by digestion of -globin chains. Biol.
Chem. Hoppe-Seyler 370(8):
819- 830. [A study of plant enzymes, using
-chains of manatee and mole hemoglobin as substrates.]
Leatherwood, S.,
and R.R. Reeves (eds.). 1989.
Marine mammal research and conservation in Sri Lanka, 1985-1986.
United Nations Environment
Programme (Nairobi, Kenya),
Marine Mammal Tech. Rept. No.
1: vi + 138.
Lefebvre, L.W.,
T.J. O'Shea, G.B. Rathbun, and R.C. Best. 1989. Distribution, status,
and biogeography of the West
Indian manatee. In:
C.A. Woods (ed.), Biogeography of the West
Indies. Gainesville
(Florida), Sandhill Crane Press: 567-
609.
Marsh, H., and G.B. Rathbun.
1990. Development and application of
conventional and satellite radio-tracking techniques
for studying dugong movements
and habitat usage. Austral. Wildl.
Res. 17(1) (in press).
Morgan, G.S.
1989. Miocene vertebrate faunas
from the Suwannee River basin of
north Florida and south Georgia.
In: G. S. Morgan (ed.), Miocene paleontology and stratigraphy of the
Suwannee River basin of north Florida and south
Georgia. Southeastern Geol.
Soc. Guidebook No. 30: 26-53.
Packard, J.M., R.K. Frohlich,
J.E. Reynolds III, and J.R. Wilcox.
1989. Manatee response
to interruption of
a thermal effluent. Jour. Wildl. Manage. 53(3):
692-700.
Preen, A.
1989. Observations of
mating behavior in dugongs
(Dugong dugon). Mar. Mamm. Sci. 5(4): 382-387.
Preen, A.
1989. The status and conservation of dugongs in
the Arabian region.
Meteorological & Environmental
Protection
Administration (Saudi
Arabia), Coastal & Marine Management Series, Report No. 10, Vol. 1: xix + 200.
Preen, A.,
H. Marsh, and G. E. Heinsohn.
1989. Recommendations for the
conservation and management of dugong in the Arabian region.
Meteorological & Environmental Protection Administration (Saudi Arabia), Coastal & Marine Management Series, Report No. 10, Vol. 2: iv + 43.
Yoshii, M., M. Une, K.
Kihira, T. Kuramoto, and T. Hoshita. 1989.
Synthesis of 5
-cholestane-3 ,6 ,7
,25,26-pentol and identification of
a novel bile
alcohol, -trichechol, present
in West Indian manatee bile. Chem.
Pharm. Bull. (Tokyo) 37(7): 1852-1854.
CHANGES OF ADDRESS
Paul K. Anderson,
Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, CANADA
Aquatic Plant
Information Retrieval System,
University of Florida,
Center for Aquatic Plants, 7922 N.W.
71st St., Gainesville, Florida 32606 USA
Carlos A. Bohorquez R.,
CEINER, P.O. Box 7877,
Cartagena de Indias, COLOMBIA
Monica Borobia, P.O. Box 361,
Price, Quebec G0J 1Z0, CANADA
Jose' A. Ottenwalder, Dept.
of Natural Sciences, Florida Museum of
Natural History, University of Florida, Gainesville, Florida 32611 USA
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