Study: Caspian Sea beluga unsustainable
Results of a study conducted on the Caspian Sea beluga sturgeon fishery by scientists from the United States and Kazakhstan reveal that current harvest rates are four to five times higher than what's deemed sustainable.
Published in an upcoming issue of Conservation Biology, the study suggests that conservation strategies for beluga sturgeon focus on reducing the overfishing of adults rather than heavily relying on hatchery supplementation.
The beluga sturgeon population has declined by nearly 90 percent in the past several decades due to high demand for black caviar, inadequate management and habitat degradation, say the study's authors.
Currently, the fishery managers depend on hatcheries to sustain the population. However, survival of hatchery-reared fish in the wild is thought to be low. Additionally, genetic diversity may be compromised by hatchery practices, which can potentially jeopardize the long-term survival of all beluga sturgeon. Despite the potential threats posed by hatchery fish, regulatory agencies give higher quotas to countries with higher hatchery output.
The Convention on International Trade in Endangered Species (CITES) listed beluga and most other species of sturgeon as threatened in 1998 with an Appendix II listing. However, beluga sturgeon numbers have declined by approximately 60 percent from 1998 to 2005, showing that existing management of beluga sturgeon fisheries has not been effective, say the study's authors.
"This is the first time that anyone has calculated sustainable harvest limits for Caspian Sea beluga sturgeon and compared them to present fishing pressure," said Dr. Phaedra Doukakis, senior research assistant with the Institute for Ocean Conservation Science and the study's lead author. "We can finally attach numbers to what people have suspected — that current management of Caspian Sea sturgeon fisheries will not prevent further population decline. We hope that this study provides the evidence needed to shift mindsets and management practices."