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
Status of Caspian sturgeon: Survey catches, population estimates, fisheries management and CITES.
Pikitch, Ellen*,1, Sisengalieva, Gulsim2, 1 Pew Institute for Ocean Science, New York, NY, USA2 Fisheries Research Institute, Atyrau, Kazakhstan
ABSTRACT- More than 90% of the world production of caviar comes from sturgeon of the Caspian Sea. Since 1960, the population of the largest and most valuable sturgeon species, Beluga (Huso huso) has declined by more than 90%. The number of Beluga entering the Volga annually to spawn was about 26, 000 in the early 1960s, immediately after the construction of the Volgograd dam which blocked access to 90% of the spawning grounds in the Volga River. Beluga arriving at the Volga to spawn have declined by more than half during the 1990s, from about 7000 in 1991-1995 to about 2800 in 1998-2002. In Kazakhstan's Ural River, the number of beluga sturgeon entering the river system declined from 3,900 individuals in 1994 to 2,500 individuals in 2002. The Beluga fishery displays characteristics typical of a fishery in decline: decreasing total catch and catch/effort, decreasing size and age of fish, difficulty in reaching catch quotas, and increasing black market prices. It is estimated that more than 90% of the of the Volga Beluga are hatchery-reared. The production and release of Beluga juveniles from hatcheries has declined since 1990, as well. Recent limited trawl surveys found very few spawning-age Beluga and a 39% decline in Beluga abundance in trawls between 2001 and 2002. However, a different interpretation of these trawl data by CITES estimated that numbers of Beluga increased from 7.6 million in 1998 to 9.3 million in 2001, and to 11.6 million in 2002, an increase of 25% in only a single year. These higher population estimates are based on assumed sturgeon catchability of 4-10 %, but catchability of 50% or less is commonly assumed for large benthic fish in the US and Europe. Recalculation of Beluga population size assuming 50% catchability suggests that Beluga populations may be less than one million. More comprehensive modeling of Beluga populations based on data from 2003-2005 indicates that the population remains low and continues to decline.
Key words: Caspian, sturgeon, beluga, Huso