No Way Out Ecosystem
No Way Out
The fate of the Caspian seal may have been decided ﬁve million years ago.
The smallest earless seal on Earth, Pusa caspica, is the only mammal in the Caspian Sea. It is atop the aquatic food chain in this closed ecosystem. As such, its well-being—in fact, its sur-vival—is dependent on the health of the system, because it has nowhere else to go. Five million years ago, a trap was set for the Caspian seal when the landlocked Paratethys Sea began to shrink, leaving over time only the Black, Caspian, and Aral seas [see “Fate of the Caspian Sea,” Natural History, 12/11–1/12]. The Black Sea re-connected to the world’s oceans, but the door has remained shut for the Caspian Sea and for its rich biodiversity, including more than three hundred endemic species.
The Caspian seal belongs to the Phocidae family. Its closest relative is the enormous grey seal (Halichoerus grypus) of the North Atlantic. The grey seal can grow up to ten feet long and weigh 880 pounds. By comparison, Caspian seals reach a maximum length of just over ﬁve feet and weigh 220 pounds at their heaviest. They are most at home in the water, remaining submerged for up to forty-ﬁve minutes, feeding mainly on kilka (Clupeonella spp.), other small ﬁsh, and shrimp. For most of the year, seals travel throughout the Caspian— a total surface area of 143,200 square miles—from Russia and Kazakhstan in the north to Turkmenistan in the east, Iran in the south, and Azerbaijan in the west. Some seals feed close to shore; others ﬁsh in deeper water, diving to depths of more than 1,600 feet.
As winter approaches, these creatures gather on the shores of Russia and Kazakhstan to await the formation of ice ﬁelds, usually in January. At this point, breeding begins. Breeding on ice may be a character trait derived from their Arctic relatives or may be a carryover from when the climate was colder around the Caspian Sea. As soon as ice sheets form, seals are quick to choose and defend breeding sites. They look for a crack or pool in the ice, or they make their own water access holes as ice is forming, in order to ﬁsh or to escape predators. Because there is little snow accumulation along these North Caspian coasts, seals don’t build lairs on the ice, as Atlantic and Baltic species do.
Females give birth to one pup per year. Mother-off-spring pairs gather in small, loosely spaced groups until ice ﬁelds shrink, and then thousands form dense aggregations on dwindling ice sheets. After feeding in the water around and below the ice, females return to these colonies to suckle their pups. Newborns don’t venture into the chilly water. Although their long, white fur protects them from cold surface elements, pups rapidly freeze to death when their fur gets wet. Offspring are weaned and left to fend for themselves three to ﬁve weeks after birth. By then, a fat layer has formed under their skin to protect the young animals from every kind of cold, wet or dry. They also molt for the ﬁrst time. As the remaining ice is melting in late March and early April, adults molt and juveniles must learn on their own to dive into the open sea to feed on shrimp, kilka, and gobies.
Caspian seals reach sexual maturity around eight years of age. They can live up to ﬁfty years, but females stop becoming pregnant around age thirty. For fertile females, mating resumes a few days after giving birth. There is no sexual dimorphism in Caspian seals, so mating is likely between one male and one female, although no evidence of this pairing has been observed during the eleven-month gestation period. After the communal activities of breeding, weaning, molting, and mating, seals disperse to forage throughout the Caspian. After a summer of foraging, pregnant seals leave non-breeding adults and head back to the northern coasts to give birth and to repeat the cycle.
The Caspian seal population numbered more than one million in the late nineteenth century. One of the seal’s popular aggregation sites was the coast of the Absheron Peninsula, in the Azerbaijan Republic. Jutting with an eagle-head shape into the central Caspian, the peninsula and its surrounding islands once harbored up to 200,000 seals. By the 1970s, that number had dropped to 2,000, according to Tariyel M. Eybatov, director of the H. Zardabi Natural History Museum at the Azerbaijan National Academy of Sciences (ANAS). Since 1971, Eybatov has been conducting semi-annual studies of the Caspian Sea and its seal population. In the decade that followed Eybatov’s ﬁrst surveys, less than 1,000 animals were observed in and around the Absheron Peninsula. In Shahdili, an area of the peninsula that had been set aside in 1969 to protect gazelles and seabirds, Eybatov and colleagues from England and Iran counted fewer than three hundred seals in 2001 and around one hundred in 2002. The situation prompted Azerbaijan’s government to develop the area into the Absheron National Park as a preserve for marine life. In the winter of 2005, when the development started, scientists found two seals in Shahdili and since then, there have been no sightings of living seals.
The ﬁrst international concern for the plight of the seals and the health of the Caspian Sea ecosystem were raised in the spring of 1997 when a mass mortality of seals was reported on beaches near Azerbaijan’s capital, Baku, located on the Absheron peninsula. The environ-mental manager of the Azerbaijan International Operating Company (AIOC), which has oil and gas ﬁelds off the Absheron coast, reported the mortalities to the World Bank, which was forming the Caspian Environ-ment Programme. Together, the World Bank and AIOC launched an investigation into the seals’ cause of death. Tissue samples showed extraordinarily high levels of organochlorine (mainly in the form of DDT) in two of the dead seals; a previously unknown strain of canine distemper virus (CDV) was found in the brain of one adult female.
These ﬁndings, combined with Eybatov’s thirty years of data on the steep decline in sightings of living seals, prompted the World Bank to fund an ecotoxicology project to further investigate what was causing seal mor-tality and to determine how pervasive DDT and other contaminants might be in the Caspian ecosystem. The new Ecotox project would study seals and ﬁshes, including the critically endangered sturgeon. Just as the research was getting underway in 2000, a second mass die-off occurred. According to a study by the team lead by Seamus Kennedy, at the Department of Agriculture and Rural Development, Belfast, Northern Ireland, more than 10,000 seals died during April and May along the Kazakhstan coast. High death rates were also reported in May and June along the Absheron peninsula and the Turkmenistan coast. The researchers presented evidence in a paper that appeared in the November-December 2000 issue of Emerging Infectious Diseases “that canine distemper virus infection was the primary cause of these deaths.”
When a third wave of deaths occurred in 2001, researchers became concerned about the size of the re-maining seal population, and the rate of death per year. These questions spawned a new mission: the Caspian International Seal Survey (CISS), which gave birth to the Caspian Seal Conservation Project (CSCP) of the Darwin Initiative program in the United Kingdom. The project started in September 2006 as a workshop in Baku, during which scientists took a trip along the Absheron coast in search of live seals. They found none.
In 2008, CISS published the results of its survey. Based on about 21,000 pups born in 2005, CISS estimated that the total seal population for that year was 104,000 and that the population was dropping by at least three to four percent annually. The rate of decline was sufﬁcient for the International Union for Conservation of Nature (IUCN) to change the Cas-pian seal’s status on its Red List of Threatened Species from “Vulnerable,” which it had been since 1996, to “Endangered.”
Scientists pursued several lines of inquiry into the causes of the population decline. Research by Mafumi Watanabe and Natsuko Kajivara at the Center for Marine Environmental Studies at Ehime University in Japan, suggested that the infertility of females from the late 1980s to the 1990s was a consequence of pollution, which had led to similar issues in the Baltic, where the water is more polluted than in the Caspian. Other scientists attributed the barrenness to the older age of breeding females. Even though research, as reported above, by Eybatov and colleagues and, subsequently, by Thijs Kuiken, at the Institute of Virology at Erasm University in Rotterdam, The Netherlands, found evidence that the deaths in 1997, 2000, and 2001—mostly of young seals—was caused by canine distemper virus, there have been no overt signs of CDV in any dead seals in the last ﬁfteen years. Scientists believe, however, that the lethal virus still lives in the population.
Seal hunting in winter breeding grounds—primarily for fur and fat—has been recorded since 1867. According to a Seal Conservation Society (SCS) report, early records show the annual number of seals killed ranged between 30,000 and 110,000, of which about half were pups. The annual kill appears—from possibly inaccurate records for the time period—to have fallen in the early 1920s to a range between 16,000 and 24,000 and then rose again to about 100,000 around 1940, and then fell back to around 40,000 seals per year. From the 1960s, the annual kill on ice ﬁelds has been limited to pups because of their valued fur, or lanugo, and the reported kill fell steadily until the end of the twentieth century. Commercial hunting ceased brieﬂy around 1996. The sealing ships in the Kazakhstan port of Fort Schevchenko became rusting hulks. However, Russians resumed smaller-scale hunting around 2004.
SCS further reports, “Russia leads a Caspian inter-governmental quango, the ‘Aquatic Bioresources Commission’ and—ignoring IUCN ‘Endangered’ status and the results of the aerial surveys of the breeding population—continues to consider the Caspian seal to be a ‘harvested species’ and to issue ‘quotas’ of 18,000 seals, mainly to Russia and Kazakhstan, although in reality only Russian hunters kill a few thousand pups when they are able to ﬁnd them. In addition to this ‘legal’ hunting in Russia, seals are killed on the ice illegally, and are also caught in ﬁshing nets. It is currently estimated that about 12,000 seals are caught annually in large-mesh nets illegally set for sturgeon in the North Caspian, and that by-catch (and sometimes deliberate catch) in ﬁshing nets is now the single most serious factor in the continuing population decline.”
The Caspian seal’s food resources have also been in decline. Mechanized commercial ﬁshing has reduced the kilka on which seals heavily depend. Stock of kilka and other small ﬁshes have also been reduced by the accidental introduction in the 1990s—from ships’ ballasts transported through the Volga-Don canal from the Black Sea—of a small, medusa-like jellyﬁsh, Mnemiopsis leidyi, which is a voracious predator of the zooplankton on which small ﬁsh depend.
To deal with the alarming fate of Caspian seals, the ﬁve countries that border the Caspian Sea agreed in 2007 to a Caspian Seal Conservation Action Plan that lays out concrete measures to avoid further decline. Kazakhstan and Iran, recognizing the seal’s desperate plight, were quick to create preserves. Iran also maintains an active educational awareness program among ﬁsherman and indigenous people. The Azerbaijan Natural History Museum manages public awareness campaigns for schools in Baku. Azerbaijan president Ilham Aliyev signed an executive order, allocating $2.3 million for the installation of small-scale wastewater treatment plants in order to reduce pollution in coastal waters, especially around the Absheron Peninsula. The technologies are already in operation in some districts of Baku. An additional $1.3 million is allocated for next year. In 2011, Akif Ali-Zadeh, current president of the ANAS, proposed the creation of a research facility to better understand the Caspian ecosystem. Within three days the proposal was approved by president Aliyev and another government ofﬁcial, and there is now a Caspian Research Center at ANAS in Baku.
Even though the Russian Federation ignores the endangered status of the Caspian seal and continues to permit hunting, as discussed above, the Federation’s Ministry of Agriculture has reinstated a 2004 ban on hunting during the breeding period from January 25 to March 31 and during the two months of ice formation. The ministry emphasizes that the ban doesn’t apply to other times of the year, but the limited restriction could be a ﬁrst step toward an eventual full abandonment of government-sanctioned seal hunting.
Perhaps as a consequence of local and international public awareness efforts, and pressure, seal births grew in 2009—just after the status change in the Red List—from the previous annual average of 6,000 pups to 19,000. Unfortunately, births went down to 16,000 during the winter of 2011–2012.
It has now been forty-ﬁve years since Tariyel Eybatov ﬁrst started quietly monitoring conditions of the ecosystem on and surrounding the Absheron Peninsula. He says it is difﬁcult to see a rebound of former habitats around Absheron because of increasing human disturbances, but he is not deterred from advocating urgent actions in the hope that the seals will return. To him, the fragile plight of seals is not a consequence of any single factor but is a combination of forces: hunting, mechanized commercial ﬁshing, increased pollution ﬂowing into but not out of the Caspian Sea, reduced food resources, and numerous other human disturbances.
Although geological events ﬁve million years ago deﬁned the territory of the Caspian seal, they didn’t decide the animal’s fate. The landlocked region can’t be washed and its web of life can’t be updated or reinforced by the world’s oceans. So now the Caspian Sea and its seals are suffering from challenging conditions affected by growing human activity. There are ﬁxes to the problems, but they are dependent on humans ﬁxing them. The prospects are not promising but there is no other way out.