Police in the Khabarovsk region have seized nine tons of critically endangered sturgeon bound for markets across Russia.

Suspicions were raised when the owner of a shipping container refused to show up when summoned to witness a search. When officers opened the crate, they found it "crammed top to bottom" with the fish, RIA-Novosti reported Monday.

"According to operational information, this fish was destined for markets not only in the Far East but also in central Russia," police said in a statement.

The statement added that police believed the captured consignment might be part of a larger haul, some of which already may have been sent to other parts of the country.

The commercial fishing of the Amur River sturgeon and its slightly more widespread relative, the Siberian sturgeon, were banned in 1958 after over-fishing led to a catastrophic population drop. Poaching the fish carries a maximum sentence of two years in prison but remains widespread.