Pusa caspica

16.

Caspian Seal

Pusa caspica

French: Phoque de la Caspienne / German: Kaspi-Ringelrobbe / Spanish: Foca del Caspio

Taxonomy. Phoca caspica Gmelin, 1788,

“In mari, praesertim septentrionali, etiam Pacifico et Caspico [= Caspian Sea].”

This species is monotypic.

Distribution. Caspian Sea.

Descriptive notes. Total length up to 150 cm (males) and 140 cm (females); weight 75-86 kg. Newborns are 65-80 cm in length and weigh c.5 kg. Male Caspian Seals are slightly larger than females when physically mature. Offspring are born with a long white lanugo (fine, soft hair) that they molt at ¢.3 weeks old;it is replaced by mostly uniformly gray hair. Adult Caspian Seals have dark spots on a lighter gray background dorsally and on a paler gray to white background ventrally, and adult males can also have scattered spotting ventrally compared with few ventral spots on adult females.

Habitat. Restricted to the inland Caspian Sea in western Russia. Caspian Seals are often associated with ice that forms in the shallow northern part of the Caspian Sea in autumn and winter.

Food and Feeding. The diet of the Caspian Seal is relatively diverse, depending on location. It includes some crustaceans in autumn and winter, and clupeid fish (Clupeonella spp.), sand smelts (Atherina boyeri caspica), carp, and Caspian roach (Rutilus rutilus caspicus) in spring and summer. Species of Clupeonella historically make up a major proportion of the total annual diet of the Caspian Seal. When Caspian Seals are in the Ural Estuary in autumn, they focus on carp, pike-perch (Sander lucioperca), and Caspian roach.

Breeding. Caspian Seals are born on sea-ice from late January through early February and are weaned at 4-5 weeks old. Females bred shortly after their offspring are weaned in late February-March, or slightly earlier if they did not give birth that year. Females are sexually mature at aboutfive years old, but most females do not give birth for the first time until they are about seven years old. Males are sexually mature at ¢.6-7 years old. Caspian Seals appear to be monogamous. Maximum age of Caspian Seals collected from Pearl Island was 43-5 years for females and 33-5 years for males.

Activity patterns. Adult female Caspian Seals molt in late February and early March, and adult males molt in late March and early April. Despite centuries of intense commercial harvest of Caspian Seals,little is known about their behavior.

Movements, Home range and Social organization. Many Caspian Seals move to the north-eastern, shallow reach of the Caspian Sea in autumn when ice begins to form. They remain there, maintaining breathing holes in ice, until early May when they molt and begin to move south in summer to the deeper areas of the Caspian Sea. Others assemble in the middle of the sea after it freezes over, and a few breed on islands in the southern Caspian Sea.

Status and Conservation. Classified as Endangered on The IUCN Red List. Caspian Seals have been hunted for several hundred years, with annual harvests of ¢.160,000 ind/ year in the late 1700s and early 1800s. On average, c.115,000 Caspian Seals were killed from the 1860s through the late 1930s, with a record number of ¢.227,000 individuals killed in 1935. Regulation of the harvest of Caspian Seals began in the late 1960s, with annual harvests after that of ¢.60,000 weaned offspring. The population is estimated to have numbered c.1-1-5 million individuals but declined by ¢.90% to ¢.100,000 individuals by 2005 because of unsustainable harvesting during most of the 20™ century. Mass mortality events in 1997, 2000, and 2001, which killed several thousand Caspian Seals each year, have been attributed to a canine distemper-like virus. Substantial loss of habitat has resulted from reduction of freshwater input to the Caspian Sea because of dams on the Volga River to divert water for agriculture. Commercial fishing and pollution have reduced prey availability, causing reproductive failure of Caspian Seals, greatly compromising their future.

Bibliography. Harkénen (2008), Harkénen, Harding et al. (2012), Harkénen, Jissi et al. (2008), Kennedy et al. (2000), Krylov (1990), Miyazaki (2009), Palo & Vaino6la (2006), Sharipov (2012), Watanabe et al. (1999).