Complex sentence: Beluga caviar consists of the roe (or eggs) of the Beluga sturgeon although found primarily in the Caspian Sea, it can also be found in the Black Sea basin and occasionally in the Adriatic Sea.
Split into simpler sentences: Beluga caviar consists of the roe (or eggs) of the Beluga sturgeon found primarily in the Caspian Sea. Although it can also be found in the Black Sea basin and occasionally in the Adriatic Sea.