51813_Sturgeon biodioversity an.PDF

Environmental Biology ofFishes48:231–239,1997.
© 1997 Kluwer Academic Publishers. Printed in the Netherlands

Endemic sturgeons of the Amur River: kaluga, Husodauricus,and Amur

sturgeon,Acipenser schrenckii

Mikhail L. Krykhtin & Victor G. Svirskii
PacificResearch Institute of Fisheriesand Oceanography, 4 Shevchenko Alley, Vladivostok 690600, Russia

Received 2.8.1994 Accepted 8.3.I996

Key words: anadromy, population, hybridization, endangered species, poaching

Synopsis

General biological characteristics and the contemporary status of the kaluga,Huso dauricus,and Amur stur-

geon,Acipenser schrenekii, are described. Both inhabit the Amur River basin. Kaluga is the largest freshwater

fish in this river system reaching inore than 5.6 m in length and inore than 1000 kg in weight. We recognize four

populations of kaluga: the f'irst is from the estuary of the Amur River and coastal brackish waters of the Sea of

Okhotsk and Sea of Japan. the second is from the lower Amur River, the third is from the middle-Amur. and

the fourth occurs in lower reaches of the Zeya and Bureya rivers. Freshwater and brackish water morphs exist

in the estuary population, with the freshwater morph predominating in number. The number of individuals in

the lower Amur River population at age 2 or greater was recently estimated to be 40 000,and in the middle

Amur, 30 000.The population will continue to decline because of rampant overfishing. The Amur sturgeon is

represented in the Amur River basin by two morphs: brown and gray. Brown morphs occur in the middle and

lower parts of the Amur River: they grow more slowly than the gray ones, Today, the lower Amur River

population of Amur sturgeon is made up of 95 000 fish at age 2 or greater and is approximately half as large as

the population in the middle Amur River. Populations of kaluga and Amur sturgeon in the Zeya and Bureya

rivers are extremely small and on the verge of extinction.

Introduction

The Amur River in the Russian far east is home to

four species of the family Acipenseridae, kaluga

Huso dauricus,Amur sturgeonAcipenserschren-

ckiiSalihalin sturgeonA. mikadoi,and sterletA.

ruthenus. Only kaluga and Amur sturgeon are en-

demic to this river (Berg 1948, Nikolslkii 1956). Sak-

halin sturgeon was recorded in the Sea of Okhotsk

from the Amur River estuary to northern Japan and

the Korean Peninsular (Berg 1948, Artyukhin &

Andronov 1990, Shilin 1995). and five to ten Sak-

halin sturgeon are caught annually in the Amur

River estuary. Sterlet was introduced into the Amur

River from the Ob River in 1956–1959, and since

then only a few sexually mature individuals have

been caught in the Amur.

Historically, kaluga and Amur sturgeon were

commercial species. In 1891,595 metric tons of kalu-

ga and 607 metric tons of Amur sturgeon were

caught in the Amur River, constituting 42.5% of the

total catch of all fishes in the Amur River that year

(Kryukov 1894). Asin many other places, the sur-

vival of sturgeon populations in the Amur River be-

came problematic after the turn of the 20th century.

By 1909, the catch of kaluga decreased to less than

one third and that of the Amur sturgeon to about

one fifth of 1900 levels. From 1915 until 1917, Rus-