Russia: Believed-to-be-extinct Abrau Sprat Rediscovered

In October 2019, researchers collected nine small fish during an expedition from Lake Abrau in the Krasnodar region of western Russia. Recent DNA analyses have confirmed that the captured fish are indeed the endemic Abrau sprat (Clupeonella abrau), a species that had not been recorded since 2008.

Challenges for the Abrau sprat: Changes in the ecosystem

It was already suspected that the Abrau sprat had gone extinct, as the ecosystem of the small lake, which originally hosted only five native fish species, had been drastically altered since the early 21st century due to the introduction of 18 foreign species and water extraction. The population of the Abrau sprat was still abundant up until 1996 but sharply declined after the zander (Sander lucioperca) was introduced into the lake. For a long time, it was unclear whether the species was still part of the lake’s fish fauna.

To confirm the identity of the captured fish as Clupeonella abrau without a doubt, scientists compared the mitochondrial genome of the modern samples with a museum specimen of the Abrau sprat from 1938. The difference between the genetic data of the museum and modern samples was 0.92 percent. This allowed researchers to confirm that the species still exists in the lake and is reproducing.

The Abrau sprat, a member of the herring family (Clupeidae), is native exclusively to the freshwater of Lake Abrau, which lies about 70 meters above sea level near the Black Sea. Due to its very limited range, the species is considered highly endangered. It primarily feeds on crustaceans.

A survey of the lake in 2006 revealed that very few Abrau sprat remained, which led the International Union for Conservation of Nature (IUCN) to classify the species as “critically endangered.”