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: 1-202-265-7055). It is supported by the U.S. Marine Mammal Commission

and Sea World, Inc.

NUMBER 25 APRIL 1996

IN THIS ISSUE: - MASSIVE MANATEE DIEOFF IN FLORIDA (p. 6)

- ON CULTIVATION GRAZING BY DUGONGS (p. 8)

- WHEN SEACOWS WALKED ON FOUR LEGS (p. 10)

EDITORIAL: BAD NEWS OR GOOD?

Several significant developments for Florida manatees have occurred since our last issue. One is the publication of the workshop volume on manatee population biology edited by Tom O'Shea, Bruce Ackerman, and Franklin Percival (see Recent Literature, below). The upshot of the two decades of painstaking work summarized in this impressive compilation is that Florida manatees actually seem to have increased in numbers since protective efforts were begun. At the end of the volume, O'Shea and Ackerman conclude that "the increases in numbers of manatees counted in aggregation areas in winter reflected an increase in the Florida population from the 1970's through the 1980's .... We are uncertain whether such a trend continued in the 1990's." Furthermore, "Reproduction parameters revealed by studies presented in these proceedings ... indicated the potential for more rapid growth than previously recognized": as high as 7% per year at Crystal River. "This higher potential for population growth makes the probability of true population growth in other areas during the 1970's and 1980's more plausible than previously thought...."

These conclusions were promptly underlined by the results of two statewide aerial surveys conducted by the Florida Department of Environmental Protection after cold fronts in January and February 1996: total counts of 2,274 and 2,639 manatees, respectively. These numbers are dramatically higher than the previous high count of 1,856, made in 1992; and as minimum estimates of actual manatee abundance, they show that the true population size is
closer to 3,000 than to the figure of 2,000 routinely quoted in recent years. Although survey coordinator Bruce Ackerman noted in a press release that weather conditions nearly perfect for

counting manatees accounted in part for this result, the evidence for a growing manatee population seems to be mounting.

What are we to make of this? Is the manatee population on the road to recovery and removal from the endangered species list? Have all the protective regulations had their desired effect, so that no further constraints on boaters or developers are needed? If manatee numbers have grown along with human numbers in Florida, does that not show that human population growth is harmless to wildlife, maybe even beneficial? Was the whole uproar over the supposed plight of the manatee in fact just an environmentalist hoax to begin with? Or (to put a more charitable face on it) is this a demonstration of the self-correcting nature of science in the light of new data?

Before jumping to any of these conclusions, we should read more of what O'Shea and Ackerman had to say: "Possible increases in manatee population size since the mid-1970's may be attributable to intensified conservation. However, the threats to manatee survival and habitat loss have accelerated and are expected to increase. A turning point may soon be reached, if it has not already. This contention is supported by the possibility that upward trends in counts at power plants in winter may have diminished in the late 1980's and early 1990's ...; by the lack of a notable increase of counts and a higher number of deaths in southwestern Florida ...; by the high number of recovered carcasses in 1994 [plus a still higher number in 1995 and a disastrous start to 1996 - see other news in this issue]; and by increased numbers of boats and the more complex technology of high-speed boating.... Because of the lack of accuracy and precision in estimates of population size, the size of the Florida manatee population could decrease even while counts may seem to increase or be stable.... Given that negative effects on manatee populations will continue to increase with burgeoning human populations in Florida and that decreases in adult mortality can result in growth and long-term persistence of Florida manatee populations ..., no prudent alternatives exist to maintaining proactive, vigorous management aimed at mortality reduction."

In short, the catch is that even if the manatee population has grown under the protection it has received, we are rapidly approaching the limits of the protective measures now envisioned. The legally-mandated Manatee Protection Plans are already in place in at least four of the 13 Florida counties considered critical for manatee protection, and further tightening of regulation beyond what is in these plans is likely to be strenuously opposed. Meanwhile, the numbers of humans, boats, and new developments continue to grow without limit. An aggressive manatee-protection campaign has bought the population valuable time, but the onslaught of demography will soon throw the manatee and its allies back on the defensive, facing ever-grimmer odds. The population recruitment suggested by the latest synoptic surveys may still prove to have been no more than reinforcements thrown into a losing battle.

The shape of this battle is already evident to those who read the published evidence more closely. O'Shea and Ackerman cite "data ... that suggest substantial population growth from internal recruitment at the Crystal River and at Blue Spring and slower growth or stability on the Atlantic Coast...." These preliminary results show, in other words, that manatees have increased in precisely those areas where they are most strictly protected, but may have been unable to do so where boating activity and boat-caused mortality are heaviest. What we see here, in fact, is an inadvertent experiment to determine what level of human harassment manatee populations can tolerate. The results neatly demonstrate both their ability to flourish, given reasonable protection, and (more realistically) their likely inability to survive much longer, as the worst that Florida is presently throwing at them worsens still further.

This was not, however, the message that was reaching the public in the wake of the 1996 synoptic surveys. As manatee researchers anticipated when the State of Florida began these surveys several years ago, they are two-edged weapons. While it is always useful to have minimum counts to plug into population models, the danger is that these minimum counts will be taken as actual estimates of population size, and growth in these numbers will be misinterpreted as actual growth in population. They are in fact being misinterpreted this way in the Florida press, by boating advocates and others, and some have even begun to call for downlisting of the Florida manatee to a less endangered status.

The issue of downlisting should, in principle, be easy to dismiss. The revised Florida Manatee Recovery Plan (1996 version, due to be published in a few weeks) states that "downlisting should be considered when ... the population is growing or stable, when mortality factors are controlled at acceptable levels or are decreasing, and when critical habitats are secure and threats to them are controlled or decreasing." Of these three criteria, it is obvious that the latter two are not likely to be met in the foreseeable future: human-caused mortality continues to rise, and the threats of human population growth and development pressures are anything but "controlled or decreasing." In practice, however, only the first criterion readily registers in the public consciousness, where higher manatee counts necessarily mean a recovering population.

Sometimes, however, one problem is solved by another; and the misleading press coverage of the January and February surveys was fortuitously swept from the headlines by the disastrous manatee dieoff in March. For the moment, this antidote of well-founded alarm seems to have taken effect, but spells of complacency are bound to recur. When they do - and whenever any of us has occasion to communicate with the public or the mass media on these issues - we need to emphasize as strongly as possible the following points:

1. The statewide synoptic surveys provide only minimum counts, not estimates of the total population; they are extremely sensitive to weather conditions and cannot be compared statistically with each other or with estimates derived from other techniques.

2. While it is possible that the total manatee population in Florida has increased, it is more certain (and more significant) that increases have occurred in precisely those areas where manatees are best protected, while in areas of lesser protection there has been little or no increase (and none that is likely to be sustained).

3. We can take no comfort in any numerical increases that have been achieved, because the protective measures that made them possible are approaching the limits of political acceptability, while the threats to manatees only increase and can be expected to wipe out the recent gains. For this reason, no talk of downlisting the Florida manatee is even remotely justified.

4. The manatee population is still small in absolute terms, and always vulnerable to unexpected catastrophes like the March 1996 dieoff - especially when, as in this case, the victims are predominately adults in their prime, which are the animals most essential to survival of the population. When some 2% of that population can be wiped out in one such event - over and above all other sources of mortality - there is ample cause for concern about the species' future.

Not all these points are easy to make in sound bites, but this is the message we urgently need to get out. - DPD

DEATH REPORTED

Jesse R. White, D.V.M.

Dr. Jesse White, well-known marine mammal veterinarian, died on 23 January 1996 at his home in Dunnellon, Florida, at the age of 61 years. A native of Oklahoma, he received his D.V.M. degree from Texas A&M University at College Station in 1962. He served as Staff Veterinarian at the Miami Seaquarium, 1967-86, and Marine Mammal Veterinarian for the Florida Department of Natural Resources, Homosassa, Florida, 1986-87. In 1984, he founded the Florida Manatee Research and Education Foundation, an organization for which he always served as Director and President. He was an Adjunct Professor at the College of Veterinary Medicine, University of Florida, 1983-87, and Clinical Professor in the Department of Small Animal Medicine at the same institution from 1987 until his death. He received several lifetime achievement and conservation awards from professional associations, and was the first veterinarian to serve on the U.S. Marine Mammal Commission's Committee of Scientific Advisors. His publications focused on manatees and marine mammal care and maintenance. He was particularly interested in captive breeding of manatees, and it was during his tenure at the Miami Seaquarium that the first successful and regular breeding of captive Florida manatees began. (John R. Twiss, Jr. and DPD)

SHOULD THE SIRENIA SPECIALIST GROUP ESTABLISH A HOME PAGE

ON THE WORLD WIDE WEB?

A couple of weeks ago, I attended a meeting of the IUCN Species Survival Commission (SSC) Steering Committee which was held in Australia. I was invited to attend the meeting as an observer along with other Specialist Group Chairs from the region. The Australians enjoyed being the only delegates not suffering from jet lag, a reverse of the usual situation.

The issue of communication among and within Specialist Groups was discussed. The SSC is planning to set up a home page on the World Wide Web which will concentrate on being a link among the home pages established and maintained by various Specialist Groups. This initiative raises questions for the Sirenia Specialist Group:

_ How many members would have access to a Sirenia SSG home page on the World Wide Web if one were established?

_ Is there anyone who is prepared to establish and maintain such a page?

The page would have many advantages. Here are a few:

_ It would be a source of up-to-date information on manatees and dugongs.

_ It would be an additional method of distributing this newsletter.

_ It could enable Group members to access the gray literature and publications lists of other members, etc.

_ It could be an effective method of distributing the Dugong and Manatee Action Plans when they are finalized.

I do not see a Sirenia Specialist Group home page duplicating the role of MARMAM.

Your reactions, please; and is there a volunteer who is willing to establish and maintain the page? - Helene Marsh

NIRS BREAKS THROUGH SIRENIAN FOLIAGE

The conventional methods used for analyzing nutrient contents of seagrasses are laborious and expensive. This is essentially why most studies dealing with sirenian and/or seagrass nutritional ecology have limited numbers of replications. This may now be a thing of the past.

Near-infrared reflectance spectroscopy (NIRS) has been in use for the analysis of agricultural and food products since the late 1960's. This technique makes use of a small segment of the electromagnetic spectrum (just above the visible region, 700 nm to the edge of the infrared region, 2500 nm), called near-infrared (NIR). The NIR spectrum contains information on the major building blocks of the biological world (CH, OH, and NH groups).

I applied this technique in my research entitled "The ecology of seagrasses as food for dugongs and green turtles" at James Cook University. It allowed me to predict multiple constituents of seagrass relevant to a dugong's (and green turtle's) perspective, for a large number of samples (ca. 1,200, which would have been expensive and laborious using conventional methods). This technique allowed me to select the "best" (most typical) calibration set (15-20% of the total), based on the population's spectral variability, for which precise conventional nutritional/chemical analyses were performed. These calibration data were then used for the development of predictive equations for each constituent using a cross-validation technique. The predicted values have a good agreement with the laboratory values. The r² values for the different constituents were: 0.99 for nitrogen, 0.96 for organic matter, 0.94 for neutral detergent fiber, 0.91 for acid detergent fiber, 0.90 for lignin, 0.91 for water-soluble carbohydrates, and 0.92 for in vitro dry matter digestibility.

NIRS analysis offers several advantages. It is rapid, nondestructive, and environmentally safe. One of its most important features is that it can analyze samples for multiple constituents. Even though this technique has existed for more than 20 years, it has never been employed in nutritional ecology of wildlife. This technique will certainly simplify the task of trying to understand why sirenians prefer certain species of foliage. - Lem V. Aragones

COURSES ON ZOO ANIMAL BEHAVIOR AND WELFARE

Edinburgh Zoo, in conjunction with the University of Edinburgh, is again offering a two-week summer school course from 15 to 26 July 1996 on Zoo Animal Behaviour and Welfare. It is designed for all those involved in management and husbandry of captive animal populations, and will update participants on the latest scientific theory and its practical implementation. Registration deadline is 31 May 1996.

A new two-module short course on Assessment and Implementation of Animal Welfare Programmes will also be offered on 1-3 November and 6-8 December 1996. (The first weekend module will cover scientific assessment of animal welfare; the second, animal welfare in practice.) Covering aspects of the new Royal College of Veterinary Surgeons' Certificate in Animal Welfare, Ethics and Law, this course will introduce the current scientific methods that are used to assess and understand animal welfare and demonstrate how these can be practically implemented.

For information on either course, contact Hamish Macandrew, UnivEd Technologies Ltd., FREEPOST, 16 Buccleuch Place, Edinburgh EH8 0LL, UK; tel.: 0131-650-3475; fax: 0131-650-3474.

LOCAL NEWS

AUSTRALIA

Dugongs Take Years to Recover From Seagrass Loss. - Preen and Marsh (1995) report dugong deaths associated with the loss of some 1000 km² of seagrass in Hervey Bay, Queensland, Australia, following a flood and two cyclones in 1992. Aerial surveys have been used to track the resultant changes in dugong numbers in the region. The surveys suggest that the decline had ceased by 1993:

Date Population Estimate

1988 2206 ± s.e. 420

1992 1109 ± s.e. 383

1993 579-629 ± s.e. 126

1994 807 ± s.e. 151

However, calf counts associated with the surveys suggest that the population may take even longer to recover than originally predicted.

Date % Calves

1988 22

1993 2.2

1994 1.5

These figures parallel changes in the pregnancy rate and proportion of reproductively active males in Torres Strait dugongs coincident with an extensive seagrass dieback in that region in the mid-1970's (Marsh 1995). Data from Australia suggest that large-scale diebacks of tropical seagrasses, often associated with extreme weather events such as floods or cyclones, are relatively common (Poiner and Peterken, 1995). In addition to any direct mortality of dugongs associated with such diebacks, their impacts on the life history of dugongs in the affected area is likely to be serious and long-lasting. The only data I know of concerning temporal changes in the pregnancy rates of manatees are from Marmontel (1995), who provides evidence that suggests an increase in Florida from 1976 to 1991.

Does anyone else have any data suggesting temporal changes in the life history parameters of sirenians?

References

Marmontel, M. 1995. Age and reproduction in Florida manatees. In: T.J. O'Shea, B.B. Ackerman, and H.F. Percival (eds.). Population biology of the Florida manatee. Information & Technology Report (U.S. Dept. Interior, Natl. Biological Service) 1: 98-119.

Marsh, H. 1995. The life history, pattern of breeding, and population dynamics of the dugong. In: T.J. O'Shea, B.B. Ackerman, and H.F. Percival (eds.). Population biology of the Florida manatee. Information & Technology Report (U.S. Dept. Interior, Natl. Biological Service) 1: 75-84.

Poiner, I.R., and C. Peterken. 1995. Seagrasses. In: L.P. Zann and P. Kailola (eds.). The state of the marine environment report for Australia. Technical Annexe: 1. The marine environment. Canberra, Australia, Dept. of Environment, Sport and Territories.

Preen, A., and H. Marsh. 1995. Response of dugongs to large-scale loss of seagrass from Hervey Bay, Queensland, Australia. Wildlife Research 22: 507-519.

- Helene Marsh

CARIBBEAN REGION

Manatee Plans and Materials Being Developed. - The regional management plan for the West Indian Manatee in the Wider Caribbean was approved at the Third Meeting of the Interim Scientific and Technical Advisory Committee to the Protocol Concerning Specially Protected Areas and Wildlife (SPAW) in the Wider Caribbean Region (Kingston, Jamaica, 11-13 October 1995). The plan will be published in English, French, and Spanish.

The Caribbean Environment Programme is also supporting the preparation of manatee recovery plans in Belize, Colombia, Honduras, Mexico, Suriname, Trinidad and Tobago, and Venezuela, and the development of educational activities on manatee conservation in Belize, Jamaica, Mexico, and Suriname. It is also producing a number of educational materials for children in English, Spanish, and French on manatee conservation as part of a region-wide public awareness and education campaign. A number of these products (poster, coloring book, and bumper stickers) are available, as is a directory of manatee experts and institutions from the Wider Caribbean including Brazil. Address: Regional Coordination Unit for the Caribbean Environment Programme, 14-20 Port Royal Street, Kingston, Jamaica; tel.: 1-809-922-9267/9268/9269; fax: 1-809-922-9292. - (Source: The Pilot [UNEP], No. 13.)

FLORIDA

Major Manatee Dieoff in Southwest Florida. - Beginning 5 March 1996, fresh manatee carcasses began turning up in southwest Florida between Englewood and Marco Island. The animals were large adults, and the only gross abnormality was a diffuse bilateral pneumonia. By 10 March, as many as four carcasses were being reported per day. By the 13th there were reports of 11 deaths in one day, and the Florida Department of Environmental Protection's (DEP) Marine Mammal Pathobiology Laboratory in St. Petersburg, which was handling the necropsies, moved its operation to a field station on Sanibel Island to process the carcasses more efficiently. As of 4 April, the total number of carcasses reported in the area since 5 March amounted to 110, with the total continuing to mount as this went to press. Even if a few of these turn out to have died from causes other than that of the majority, this will still easily rank as by far the largest single mass mortality of West Indian manatees in recorded history.

All of the carcasses so far necropsied were in good flesh; none had any indication of cold stress and all had pulmonary lesions characterized as diffuse, bilateral discoloration of purple and bright red on the serosal surface of the lungs. On a cut surface, the lungs were congested and bled. In the more severe cases, the primary airways were filled with a serosanguinous exudate that was adherent and occluded the secondary airways. In the less severe cases, the airways were open, but the pulmonary parenchyma appeared the same in all cases and there was a conspicuous absence of inflammation. All other organs appeared grossly normal. Death was rapid and the result of pulmonary failure.

The vast majority of animals were large (275 cm or more); the smallest were 191 cm and there were no perinatal-sized animals involved. At least seven animals were pregnant. Tunicates were not observed in any of the GI tracts. Microbiological results indicated a diversity of bacteria that, in the absence of an inflammatory response and of consistency between cases, were considered secondary to the event.

Following the guidelines of the Marine Mammal Protection Act, the Florida DEP has requested technical advice from the Working Group for Unusual Marine Mammal Mortality Events. In addition to State biologists, Federal scientists from the U.S. Fish and Wildlife Service, National Biological Service, National Marine Fisheries Service, and Armed Forces Institute of Pathology are cooperating in the response to the dieoff, as well as scientists from the University of Florida, University of Miami, Miami Seaquarium, Sea World, and Erasmus University in The Netherlands.

In 1995, Florida reported a total of 201 manatee deaths. This year, 200 have died in Florida's waterways in little more than three months.

The same area of southwest Florida was the scene of another mass mortality in 1982 in which some 37 manatees died. These deaths were traced to ingestion of tunicates that contained red-tide organisms. That outbreak included cases of manatees behaving abnormally, and some animals recovered; but in this case there have been no reports of sick or strangely-acting manatees, only deaths. Although the 1996 incident has coincided with a red tide that has killed sea birds and other marine animals, preliminary screening of manatee blood for red-tide toxins has been negative. Neither have any of the other analyses so far produced any conclusive evidence of a cause.

On 1 April, researchers captured six manatees in the area of the dieoff and extracted blood from them in an attempt to obtain a control group of live animals with which to compare analytical findings from the carcasses. For instance, if the live animals have been exposed to the disease, they might show unusual blood cell counts or perhaps antibodies. Alternatively, whatever is causing the disease may be present in the control group's blood but for some reason absent from the blood of the animals that have died. Passive Integrated Transponder (PIT) tags were also placed in the captured animals, so if any of them turn up dead in the near future, they could provide insight into the incubation period if an infectious disease is to blame, or possibly give other clues about the cause of death. At this time a viral infection is considered a likely culprit, but unusual bacteria and natural or man-made toxins have not been ruled out. (Source: Florida DEP)

Award and New Job for Pat Rose. - Patrick M. Rose, who has headed the Florida Department of Environmental Protection's (DEP) manatee program for the past twelve years, was recently the recipient of a 1995 special edition National Conservation Achievement Award sponsored by the National Wildlife Federation (NWF).

This award recognizes contributions made by dedicated public servants in the cause of conservation. Recipients are selected by the Awards Committee of the NWF Board of Directors.

Pat has long been known for his aggressive championing of boat speed zones and other protective regulations on behalf of the Florida manatee, and has borne the brunt of many hard-fought intra-agency political battles, as well as much bitter public criticism incurred in the course of regulatory controversies. To him belongs much of the credit for the great success DEP has had to date in enacting manatee protection.

Pat instituted the Florida Audubon Society's manatee program, then became the U.S. Fish and Wildlife Service's first Manatee Coordinator, before starting DEP's manatee program. He is also a noted manatee photographer, and his still and motion pictures have appeared in many publications and films.

In recent weeks he has left DEP to become the new Director of Government Relations for the Save the Manatee Club, which has opened a new satellite office in Tallahassee in order to become more involved in advocacy for stronger manatee protection. Pat's dedication and government experience will be major assets to this effort, and his many friends and colleagues are happy that his talents will not be lost to the cause of manatee conservation. (Sources: DEP, Save the Manatee Club Newsletter)

Save the Manatee Club Goes Online. - Visit the Save the Manatee Club's new web site! Facts about manatees, information about the Adopt-A-Manatee program (including an online adoption application), and materials for educators are all featured. Address: http://objectlinks.com/manatee.

GERMANY

More on Manatee Breeding in Nuremberg. - A letter to the U.S. Marine Mammal Commission from Dr. Peter