Report request: I am a correspondent for National Geographic Magazine.  We are working on a series considering the geography of food, and for that I am presently writing about the production of caviar from the Caspian Sea.
I need a report on the extent of and reasons for the decline in caviar production from the Caspian Sea.  I want to be broad in my coverage here, so I am not just looking for verified reports from authoritative sources, but also for speculation and claims by parties that may have their own agendas for making such claims.

Assessment questions and gold answers:
question_text: What are four factors that have led to the decline of caviar production in the Caspian Sea?
gold_answers: Destruction of sturgeon's habitat
question_text: What are four factors that have led to the decline of caviar production in the Caspian Sea?
gold_answers: Pollution
question_text: What are four factors that have led to the decline of caviar production in the Caspian Sea?
gold_answers: illegal fishing
Overfishing
smuggling
question_text: What are four factors that have led to the decline of caviar production in the Caspian Sea?
gold_answers: Invasive species
question_text: What is the state of the sturgeon population in the Caspian Sea?
gold_answers: near extinction
question_text: What are the sturgeon's main spawning grounds?
gold_answers: River estuaries
question_text: What are the problems with river estuaries on the southern shores of the Caspian Sea?
gold_answers: River estuaries are narrow
river estuaries are blocked
question_text: What caused the narrowing or blocking of river estuaries on the southern shores of the Caspian Sea?
gold_answers: Sedimentation
question_text: What construction prevents fish from reaching the upper reaches of rivers in the north of Iran ?
gold_answers: Rubber dams
question_text: What is a source of pollution threatening the Caspian Sea?
gold_answers: Agricultural runoff
question_text: What is a source of pollution threatening the Caspian Sea?
gold_answers: Drilling of oil wells
question_text: What happens to the sturgeon's eggs in polluted waters?
gold_answers: eggs are destroyed
question_text: Which two countries regulated fishing in the Caspian Sea before the collapse of the Soviet Union?
gold_answers: Iran
question_text: Which two countries regulated fishing in the Caspian Sea before the collapse of the Soviet Union?
gold_answers: Soviet Union
question_text: Which countries has exclusive fishing rights in the Caspian Sea before the collapse of the Soviet Union?
gold_answers: Iran
question_text: Which countries has exclusive fishing rights in the Caspian Sea before the collapse of the Soviet Union?
gold_answers: Soviet Union
question_text: How did the collapse of the Soviet Union affect the sturgeon population in the Caspian Sea?
gold_answers: The collapse resulted in overfishing
question_text: What invasive species caused a threat to the sturgeon's food supplies?
gold_answers: Comb jelly
question_text: How did the comb jelly threaten the sturgeon's food supplies?
gold_answers: Comb jelly ate sturgeon's food source
comb jelly ate Caspian Sea sprat