PARENT SESSION
Symposium 3: Linking ecological processes and environmental impacts across scales: Coastal ecology and energy development in the Caspian Sea and Gulf of Mexico
Organized by: S Tartowski, T Butler, and V Bashkin
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 517 C, Level 5, Palais des congrès de Montréal

Caspian Seal deaths: Causes, impact on the population and prognosis.

Wilson, Susan^*,1, Harkonen , T.², Jepson, P.¹, Jussi, M.³, Eybatov, T.⁴, Goodman, S.⁵, ¹ Institute of Zoology, London, UK² Swedish Museum of Natural History, Stockholm, Sweden³ Vilsandi National Park, Estonia⁴ Institute of Geology, Baku, Azerbaijan⁵ University of Leeds, Leeds, UK

ABSTRACT- A World Bank initiative in 1997 in response to a large-scale Caspian seal mortality in Azerbaijan, found evidence of a new strain of canine distemper virus (CDV) and also very high organochlorine (OC) concentrations in the blubber of two adult males (OCs 457 and 709 mg/kg lipid weight, approx. 87% DDTs). Concern over these findings resulted in the World Bank ECOTOX project (2000-02) dedicated to determining levels of OC and other contaminants in the Caspian seals, fish, sturgeon and sediments as well as investigating causes of seal mortality. Further large-scale seal mortalities occurring in 2000 and 2001, during which more than 10,000 seals are thought to have died, were investigated. Sixteen seals were autopsied in May-June 2000 in Kazakhstan and Azerbaijan and a diagnosis of distemper was made in 11 of the seals. Later deaths in Iran in the winter of 2000 in Iran and in May-June 2001 in Azerbaijan involved mainly adults, with males predominating. Of 22 dead seals sampled, a definitive diagnosis of distemper was made for only two individuals. However, the results from both years indicated widespread exposure and immunity to CDV in adult animals, suggesting that CDV may be endemic in Caspian seals. This interpretation is supported by a 30-year data set of mortality in Azerbaijan, indicating a marked increase in mortality every few years, which could indicate a recurrent cycle of epizootics. The OC concentration range in the blubber of seals in 2000-01 was 7-823 mg/kg lipid weight (approx. 70-80% DDTs). No clear relationship between OC concentrations and either distemper or generalised bacterial infections was detected thus far in the study. The potential impact on the Caspian seal population of distemper outbreaks, high OC levels and other threats can only be judged in relation to an estimate of the total size of the Caspian seal population and its distribution. Since no reliable and transparent current population estimate was available, a new seal population survey series, using methods developed in the Baltic, has been initiated. Data from the first aerial survey of the complete winter ice field, carried out in February 2005, will be integrated into a new seal conservation action plan. This will help determine the measures necessary to promote a viable population of Caspian seals in the face of current and future threats.

Key words: caspian, seal, distemper, population survey