Amplifying Recovery Rates of Endangered Baleen Whales: The Rationale for Veterinary Intervention
IAAAM 1991
R.H. Lambertsen, PhD, VMD
Ecosystems International Inc., University of Pennsylvania Medical Center, Philadelphia, PA

Only recently has the major role of disease as a suppressor of marine mammal population growth become clear to all. In 1987-1988 hundreds of bottlenose dolphins washed ashore dead along the eastern seaboard of the United States (Scott, et al., 1988). Shortly thereafter over 17,000 harbor seals died in European waters in an explosive epidemic of suspect viral origin (Brody, 1989). In 1990 several hundred bottlenose dolphins were found dead In the Gulf of Mexico. In the past year alone a die-off of striped dolphins began in the Mediterranean Sea.

Years prior to these events the Woods Hole Oceanographic Institution, the Florida Sea Grant College, NOAA, and more recently, the Committee on the Challenges of Modern Society, NATO, sponsored an independent effort to evaluate the disease problems of large Cetacea. This research was carried out by American veterinary teams concerned with long term conservation issues. The objective was to quantify major causes of natural morbidity and mortality relative to age. Fin, sei, and sperm whales were examined as model species. Our primary concern was that population models used traditionally In fisheries management were falling to account for age-specific decrements in survivorship caused by endemic disease. Data were needed to prove that routine methods used to estimate stock productivity and to determine catch quotas were falsely optimistic. In parallel, major concern was expressed that conventional models were overestimating population recovery rates and recovery potentials (Ryther, 1986; IWC, 1986; Marshak, 1988).

Several new lines of empirical evidence which substantiate these opinions have now been documented in detail (Lambertsen, 1985; 1986; 1990, Lambertsen and Kohn, 1987; Lambertsen et al., 1987). The nonconservative nature of traditional whale population models also has been corroborated independently. Recently a shipboard survey in Antarctic waters found far fewer blue and fin whales than expected on the basis of conventional thinking (Kasamatsu et al., 1988).

All these lines of evidence provide substantive new arguments In favor of a continuation of the current moratorium on the commercial whaling. However, the results of the WHOI/NOAA/NATO sponsored effort further suggest a positive way to assist the recovery of damaged marine ecosystems. The available data indicate that blue, fin, and humpback whales suffer from a very serious parasitic disease that could well be treated to amplify natural rates of population recovery. This disease is caused by a giant and highly invasive nematode, Crassicauda boopis, which infects the kidneys of these three species of baleen whales. Patent infections typically result in the formation of reactive tissue lesions which occlude the renal veins. Mounting evidence indicates that such lesions probably can kill the whale by causing massive swelling, abscessation, and failure of its kidneys. In the North Atlantic, ninety-five percent of the fin whale population is infected (Lambertsen, 1986; 1990), with infections of the young being, by far, the most severe (Lambertsen et al., unpublished). Corresponding to this strong age-specificity, data on natural beachings of fin and humpback whales, provided to us by the Smithsonian Institution, show a major peak in mortality at or about the end of the first year of life (Lambertsen et al., unpublished). It is emphasized that the cause of this mortality peak appears to be an exacerbating relationship between the natural stress of weaning and the greater susceptibility of the immunologically naive whale calf to ubiquitous marine pathogens, including Crassicauda boopis. Further, the systemic illness and mesenteric arteritis associated with crassicaudiosis (Lambertsen, 1986; 1990) likely impairs the ability of affected whales to repel a capable marine predator, Orcinus orca. Anthropogenic impacts related to widespread marine pollution may be increasing the whales' susceptibility to this endemic disease.

Accordingly there is interest is in bringing together a group of experts to examine in detail the feasibility of therapeutically amplifying the rate of population growth of these three species of baleen whales. Blue, fin, and humpback whales all are officially endangered on account of their populations having been decimated, worldwide, by man.

Recent technological breakthroughs in the treatment of similar parasitic disease in domesticated animals provide the potent but safe medications that are needed. Available ballistic syringe technology would be used. The manufacturers of the medication of choice, after reviewing our data, offered to make their product available at no cost. It is noteworthy that the same medication is used in an international health program to prevent river blindness, a serious parasitic disease endemic to man in central Africa.

Our therapeutic intent would be to abate potentially lethal parasitic disease in the young whale calf to help it through the brief but critical period of weaning. Such an effort embraces and extends the primary objective of Congress promulgated in the Marine Mammal Protection Act of 1972. The aim is to amplify rates of recovery in these endangered species so as to improve the health and vigor of marine ecosystems. What is clear is that saving only one female calf could lead to an Increment of 20 or more new animals to the population over the course of her full reproductive lifespan. Geometric population growth would engender ecological gain for generations to come.

Further, a program enabling this action likely would bring societal, esthetic, and humane benefits of both a tangible and intangible nature. Many specific questions concerning operational details and feasibility, however, are best addressed with additional input representing diverse types of expertise. To this end the International Association of Aquatic Animal Medicine is invited to assist in evaluating the technical feasibility of this positive approach to large whale conservation and to consider its global implications. One initial objective is a detailed plan for sea trials needed to test a maritime veterinary capability which may prove of importance to the future health of ocean systems.

Acknowledgments and Literature Cited

1.  Funding for aspects of this work was provided by the Committee on the Challenges of Modern Society, North Atlantic Treaty Organization, Brussels, Belgium Views expressed by the author do not necessarily represent those of the Committee or NATO member countries. I express my gratitude to many friends and colleagues, with names too numerous to mention, who participated in the investigation.

2.  IWC, 1986. Report of the Scientific Committee. Annex M. Brody, M. Explaining sea mammal deaths proves challenging. Amer. Soc. Microbiol. News 55: 595-598, 1989.

3.  Kasamatsu, F., D. Hembree, G. Joyce, L. Tsunoda, R. Rowlett, and T. Nakano. Distribution of cetacean sightings in the Antarctic: Results obtained from the IWC/IDCR minke whale assessment cruises, 1978/79 to 1983/1984. 1988. IWC/39/SC/10.

4.  Lambertsen, R.H. Taxonomy and distribution of a Crassicauda SD. (Nematode: Sprurida) infecting the kidney of the common fin whale (Balaenoptera physalus Linne). J. Parasitology 71:485-488, 1985.

5.  Lambertsen, R.H. Disease of the common fin whale, Balaenoptera physalus: Crassicaudiosis of the urinary system. J. Mammalogy 67:353-366, 1986.

6.  Lambertsen, R.H., Birnir B. and Bauer, J.E. Serum chemistry and evidence of renal failure in the North Atlantic fin whale population. J. Wildlife Diseases 22:389-396, 1986.

7.  Lambertsen, R.H. and Kohn, B. Unusual multisystemic pathology in a sperm whale bull. J. Wildlife Diseases 23:361-367, 1987.

8.  Lambertsen, R.H., Kohn, B., Buergelt, C.D., and Sundberg, J. Genital papillomatosis in sperm whale bulls. J. Wlidllfe Diseases 23:510-514, 1987.

9.  Lambertsen, R.H. Disease Biomarkers In Large Whale Populations of the North Atlantic and Other Oceans. In: McCarthy, J. and L. Shugart (ed.). Biomarkers of Environmental Contamination. Lewis Publishers. pp.395-417, 1990.

10. Marshak, Robert M. Dean Emeritus, University of Pennsylvania School of Veterinary Medicine; President Emeritus, American College of Veterinary Internal Medicine; to Hon. George P Shultz, Secretary of State. Letter dated 22 December 1988 (public record).

11. Ryther, John H. Director, Center for Marine Biotechnology, Harbor Branch Oceanographic Inst.; Senior Scientist, Woods Hole Oceanographic Institution; and Founding Commissioner, U.S. Mar. Mamm. Comm., to Hon. Anthony Callo, NOAA Administrator. Letter dated 30 April 1986 (public record).

12. Scott, G.P., D.M. Burn, and L.J. Hansen. The dolphin die-off: long-term effects and recovery of the population. Proc. Oceans '88, Baltimore, MD. pp. 819-823. 1988.

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R. H. Lambertsen, PhD, VMD

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