Unraveling death of Caspian seals
From illegal hunting to disease outbreaks
Among the living creatures of the Caspian Sea, the Caspian seal stands out as the only mammal and one of the most familiar inhabitants of this inland sea. However, these days, it is facing severe challenges, with the deaths of several seals along the northern coastal provinces of Iran raising alarm bells among environmentalists. The threat of extinction looms larger than ever for this marine species.
The vast expanse of the Caspian Sea boasts a unique biodiversity, but this breathtaking ecosystem is grappling with numerous threats — from declining aquatic populations and rising biological pollution to the perilous status of the Caspian seal population. Currently, only about 70,000 individuals of this sole marine mammal remain in the northern sea, marked as an endangered species.
According to the International Union for Conservation of Nature (IUCN), the Caspian seal is classified as vulnerable and in dire need of protection. Yet, this responsibility cannot fall on Iran alone; Russia, Turkmenistan, Kazakhstan, and Azerbaijan must also chip in to preserve this species.
Challenges facing Caspian seals
Experts point out that violations of the Caspian Sea’s coastal boundaries, land-use changes and construction activities, commercial ship traffic, and military exercises in the northern Caspian are all taking a toll on the seals. The breaking up of ice sheets, which can cause seal pups to become separated from their mothers or fall into the water, alongside illegal hunting and the spread of an invasive comb jelly species, have all been called out as deadly threats to this marine mammal.
Because Caspian seals carry about 12% body fat, they have historically been attractive targets for hunting, especially in Russia, where their skin and meat are valued. Fortunately, thanks to the efforts of seal conservation advocates, all Caspian littoral countries and Russia have since banned hunting this precious mammal. Nevertheless, many seals still end up caught and suffocated in fishermen’s nets as some fishermen believe they have landed a valuable commodity for trade and therefore kill them.
The trade in Caspian seal pelts has caused some to continue hunting despite bans. Although global warming and the melting of northern Caspian ice have wiped out much of the seals’ habitat on their own, environmental pollution, declining populations of Kilka fish, and diseases transmitted by canids cannot be written off as contributing factors to seal mortality.
Another significant and destructive factor is the proliferation of an invasive comb jelly species called Mnemiopsis, which entered the Caspian Sea via the Volga River and has become a major threat to the region’s ecosystem. These invaders feed on plankton and small fish eggs, rapidly multiplying and throwing a wrench into the food chain. Since plankton is the main food source for Kilka fish — and both Caspian seals and sturgeon feed on Kilka — the disruption of this food web could ultimately drive the Caspian seals to the brink of extinction.
Amid various hypotheses including avian influenza, military operations, and viral and bacterial diseases as causes of seal deaths, the most plausible explanation appears to be military exercises, which are common among Caspian coastal states.
Canine distemper virus
The canine distemper virus is a highly contagious pathogen affecting canids. It is believed that seals contract this virus through contact with infected canids such as jackals while resting on land. Symptoms, predominantly seen in older seals, include eye discharge, weight loss, miscarriage, inability to dive, and lack of response to humans. Fortunately, this virus poses no threat to humans.
Until 2000, the main threats to Caspian seals were ranked as hunting, overfishing, habitat destruction, pollution, and disease. Today, with available data, entanglement in fishing nets appears to carry more weight than other factors. It is also predicted that with the expansion of oil industries and ongoing global warming, these impacts will ramp up, collectively speeding up the decline of this valuable species.
Conservation efforts, milestones
The year 2010 marked the official launch of the Caspian Seal Conservation Center on the Caspian coast, thanks to the dedication of Dutch philanthropist and nature lover Lenie’t Hart, along with researchers and experts like Amir Sayyad Shirazi and Mostafa Shahi Ferdous. Over the past eight years, the center has rolled out effective programs aimed at preserving and saving the only marine mammal of the Caspian Sea. Noteworthy achievements include rescuing 89 seals along Iran’s shores and holding conferences with officials from the Commonwealth of Independent (CIS) states.
Iran proudly stepped up as the first among Caspian littoral states to establish this center on Ashuradeh Island in Mazandaran, one of the few relatively pristine and untouched islands in the region.
The center’s primary goals include rescuing injured seals, raising environmental awareness, educating fishermen, and branching out conservation activities to neighboring Caspian countries.
Population trends, protection plans
A 2008 census estimated the Caspian seal population at around 100,000, but unfortunately, that number has since dropped off to approximately 70,000.
In response to the sharp decline, a project titled “Ecology and Pollution Study of the Caspian Sea” was launched in 2000 with support from the Caspian Environment Program, spanning all five bordering countries. Since 2006, this initiative has evolved into the “Caspian Seal Conservation Project,” backed by the Darwin Institute and the University of Leeds, aiming to assess the species’ status and reduce threats. The late Hormoz Asadi represented Iran in this project and made significant contributions to Caspian seal conservation.
Key activities undergoing to preserve the Caspian Seal include:
• Patrolling Caspian coasts to locate dead seals, determine causes of death, and collect samples for a data bank.
• Conducting aerial surveys on ice to estimate populations of breeding seals and pups.
• Attaching radio telemetry devices to seals to study their habits and identify feeding and resting areas.
• Assessing the impact of icebreaker ships on seal habitats to figure out ways to mitigate damage.
• Mapping seal distribution and identifying critical habitats.
• Educating fishing communities and raising public awareness as integral parts of the conservation process.
• Organizing regional and international meetings to swap notes among the five countries and international experts.
• Promoting the Caspian seal as a key species for the Caspian habitat at the regional level.
• Evaluating the effects of various threats on the Caspian seal population.
Together, these efforts are aimed at turning the tide for this endangered species and preserving the unique biodiversity of the Caspian Sea.
The Head of Wildlife Supervision at Mazandaran Province’s Environmental Protection Office has come forward with news that 30 Caspian seal carcasses have been discovered along the province’s coastline this year. The remains were found in the coastal areas of Juybar, Babolsar, Miankaleh, Tonekabon, and Chalus, with the highest number of fatalities being reported in the central regions of Juybar and Babolsar.
Korous Rabi’ei pointed out that Caspian seal deaths have historically peaked during late spring and summer, coinciding with their migration to Iran’s coastal waters. Based on data collected over the past three years, these mortalities may drag on until November. “Last year, dozens of seal carcasses were found washed up along Mazandaran’s shores,” he said.
He further explained that Caspian seals migrate to the northern parts of the Caspian Sea in late autumn for breeding, where the water is shallower and ice-covered. With the arrival of spring and summer, they head back to Iran’s coastal waters. Recently, two more seal carcasses were discovered intact in Juybar; Tissue sampling has been conducted, and official laboratory results are awaited.
The head of Wildlife Supervision laid out several possible causes for these deaths, including the dropping water levels of the Caspian Sea, climate change, and potential disease outbreaks, all of which require thorough investigation.
The Caspian seal, the only mammal native to the Caspian Sea and an endangered species, was once estimated to number around one million individuals two decades ago. However, according to some sources, over 900,000 seals have been wiped out due to various violations.
Caspian Sea home to 850 animal species
Spanning 436,000 square kilometers with 7,000 kilometers of coastline, the Caspian Sea is home to an extraordinary variety of flora and fauna, reportedly including over 500 plant species and 850 animal species.
One of the sea’s major draws is its diverse fish population, consisting of 78 species from 17 families. Among these, sturgeon, salmon, whitefish, pike-perch, carp, Kilka, trout, mullet, and kutum are well-known worldwide. Iran’s shores are recognized as a critical habitat and origin for this commercially valuable fishery.
Yet, amid this stunning expanse — the world’s largest inland body of water — the Caspian seal (also known as the “water dog”) stands out as the only marine mammal. Once boasting a population exceeding one million, the seal’s numbers have now plummeted to roughly 70,000 due to various factors. Each year, many seals either get caught up in fishermen’s nets or perish due to the proliferation of an invasive comb jelly species called Mnemiopsis.
The Caspian seal is the smallest true seal species — earless and found exclusively in this sea. It inhabits most parts of the Caspian, with seasonal shifts depending on food availability. During summer and autumn, most Caspian seals stick around Iran’s waters.
Mammal with two-million-year legacy
The Caspian seal’s origins trace back to ringed seals that migrated from the Arctic about two million years ago during the Quaternary period. When ice sheets between continents melted, these ringed seal populations broke off, forming isolated groups — one of which became the Caspian seal. Another isolated population is the Baikal seal, whose skull bears a strong resemblance to that of the Caspian seal.
Seals are marine creatures commonly believed to live along sea shores. In Iran during the 1980s, some Mazandaran residents recalled spotting seals, locally called “water dogs,” in quiet docks such as Neka Pier. The Caspian seal is the only native mammal of the Caspian Sea and holds immense genetic and ecological value in maintaining the sea’s food chain balance.
As a top predator widely distributed across its habitat, the seal is considered an indicator species for the Caspian Sea. Its presence signals the health of the marine environment, which many local communities depend on for their livelihood.
Generally, Caspian seals are tied to water temperature; When temperatures rise, they move down to colder, deeper waters. The Caspian Sea’s varying water temperatures across different regions have thus created a valuable habitat for these seals.
Physical characteristics, behavior
The Caspian seal has a spindle-shaped body, large eyes, small ears, and thick, long whiskers numbering about 134. When fully grown, it reaches about 1.5 meters in length and weighs up to 80 kilograms, making it one of the smallest seal species with 10 pairs of upper jaw teeth and 8 pairs in the lower jaw. Each flipper has five fingers with long nails, connected by webbing that acts like fins, enhancing their swimming skills.
Its legs are aligned with the tail, and its body is covered with short fur that is soft and white at birth, turning grayish with age and season, shedding entirely in winter. The dark spots on its back become more numerous and darker with age, while the body color lightens. Since its legs cannot bend forward, the seal must wriggle and roll to move on land.
Being earless, the Caspian seal communicates through vibrations in the water detected by its whiskers. It has poor eyesight and smell, is colorblind except for green, and primarily feeds on small fish like Kilka and sometimes crustaceans. Its diet varies seasonally, with adults consuming up to three kilograms of fish daily — around one ton annually. Due to their diet, harmful chemicals such as heavy metals build up in their bodies.
In late autumn, Caspian seals make their way to northern areas with frozen, shallow waters to breed. They create two types of holes in the floating ice for breathing, exiting, and sheltering newborn pups. Mothers protect their pups for about five weeks and mate again one month after giving birth. These mammals are monogamous, and females undergo an 11-month pregnancy, delivering pups weighing about five kilograms.
After the breeding season, seals return to southern parts of the sea. Females reach maturity between five and seven years old, while males mature between six and seven years.
Caspian seals can dive up to 50 meters and stay underwater for about one minute. Since they lack gills, they must surface for air regularly. However, dives reaching 150 meters and longer durations have been recorded. During winter, summer, and mating seasons, seals gather in large groups but otherwise lead solitary lives.
Conservation status, int’l efforts
According to the International Union for Conservation of Nature (IUCN), the Caspian seal is an endangered species. Coastal countries, along with local communities and authorities, must put together priority programs to ensure the species’ survival in the salty waters of the Caspian.
In 2003, the Tehran Convention on Caspian biodiversity conservation was signed by the five littoral states. Following this, Iran and Russia, recognizing the importance of the sea’s species, rolled out postage stamps featuring the Caspian seal and sturgeon.
The article first appeared in Persian on IRNA.