While the beluga sturgeon is popular for its fillets, its eggs, known as "true caviar," are regarded as a delicacy. Native to the Caspian Sea, these ancient fish can grow to 15 feet in length, weigh more than a ton and live to be 100 years old. Due to the popularity of their eggs, they're heavily overfished -- typically with gill nets. This particularly problematic because this species that doesn't reach sexual maturity until 20 or 25 years of age. In addition to fishing pressures, beluga sturgeon suffer from habitat reduction, having lost 90 percent of their historic spawning grounds over the past several decades. Because of these pressures, the IUCN classified the beluga sturgeon as endangered, and the population is expected to continue its decline.
Gill nets are nets that sit like a fence on the ocean floor. When a fish that is tcoo big to swim through the net tries to swim back out, it gets caught by the gills.