There are multiple reasons for the decline of caviar production in the Caspian Sea.
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These include the destruction of the sturgeon’s habitat; various types of pollution; overfishing, illegal fishing, and smuggling; and the introduction of invasive species into the Caspian.
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These factors have brought sturgeon to the brink of extinction, to the extent that it has become very difficult to even find breeding stock for sturgeon in the Caspian Sea.
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River estuaries are the main spawning grounds of sturgeon; however, most of the river estuaries on the southern shores of the Caspian Sea are narrow or completely blocked due to sedimentation.
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The sturgeon’s habitat has also been affected by the construction of rubber dams in rivers in the north of Iran, preventing the migration of fish, including sturgeon, to the upper reaches of the rivers.
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Various types of pollution, including agricultural run-off, industrial and urban sewage, have been discharged into estuaries, so that even if a fish reaches the estuary and spawns, its eggs will be destroyed to pollution.
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The drilling of hundreds of oil wells by the Caspian coastal countries is also a source of pollution.
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One of the main reasons for the decline of sturgeon in the Caspian Sea was the collapse of the Soviet Union.
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Prior to its collapse, the Soviet Union and Iran managed fishing in the Caspian Sea and no other country was allowed to fish from this sea.
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However, in the first years after their independence, the Commonwealth of Independent States started to harvest sturgeon indiscriminately, causing serious damage to this fish population.
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A few decades ago, the introduction of an invasive species of comb jelly to the Caspian Sea caused a decrease in the food supplies for sturgeon.
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The comb jelly disrupted the food cycle because it feeds on Caspian Sea sprat, which is the sturgeon’s food source.
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The decrease in the sprat population therefore resulted in decreased food supplies for sturgeon.
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Warning: these questons and answers are not all representative of the way questions will be asked and answered in the pilot, because some questions are compound and some answers do not include citations.

Q: What are four factors that have led to the decline of caviar production in the Caspian Sea?
A: Destruction of sturgeon’s habitatA: PollutionA: OverfishingA: Introduction of invasive species

Q: What is the state of the sturgeon population in the Caspian Sea?
A: It is on the brink of extinction

Q: What are the sturgeon’s main spawning grounds?
A: River estuaries

Q: What are the problems with river estuaries on the southern shores on the Caspian Sea?
A: Most are narrow or completely blocked due to sedimentation

Q: What did Iran construct in the north of Iran that prevents fish from reaching the upper reaches of the rivers?
A: Rubber dams

Q: What types of pollution have been discharged into estuaries?
A: Agricultural run-offA: Industrial and urban sewage

Q: What is another source of pollution threatening the Caspian Sea?
A: The drilling of hundreds of oil wells

Q: What happens to the sturgeon’s eggs in polluted waters?
A: They are destroyed

Q: How was fishing in the Caspian Sea regulated before the collapse of the Soviet Union?
A: Iran and the Soviet Union managed fishing in the Caspian, and no other country was allowed to fish from the sea.

Q: How did the collapse of the Soviet Union affect the sturgeon population in the Caspian Sea?
A: Overfishing resulted when the Soviet Union broke apart into the Commonwealth of Independent States

Q: What invasive species caused a threat to the sturgeon’s food supplies?
A: Comb jelly

Q: How did it threaten the sturgeon’s food supplies?
A: It ate Caspian Sea sprat, which is the sturgeon’s food source