MICROCHEMISTRY ANALYSIS OF OTOLITHS OF COREGONUS USSURIENSIS FROM THE HEILONG RIVER BASIN

Coregonus ussuriensis, one coldwater fish, is an important economic fishery species in the Heilong River basin. The resources of Coregonus ussuriensis have been seriously impacted by anthropogenic influences such as pollution, habitat degradation and overfishing. Knowing the characteristics of life history at the important stage helps to better protect the Coregonus ussuriensis. Otolith element fingerprint could objectively and specifically reflect the character of the water which fish experienced. The element Sr and Ca microchemistry patterns have been used to reflect the water type which the fish lived in. To study the characteristics of life history for Coregonus ussuriensis, an electron probe microanalyzer (EMPA) was used to analyze the element Sr and Ca microchemistry patterns in otoliths for Coregonus ussuriensis collected from Suibin and Jiejinkou section of the Heilong River main stream and Tangyuan section of the Songhua River main stream from December 2013 to January 2014. Results of line transect analysis indicated the value of Sr/Ca significantly fluctuated including a low ration (<5) responded to freshwater life and some high rations (>10) responded to seawater life, revealing they had experienced an anadromous migration. The results of X-ray mapping analysis of EMPA reflected the same feature of anadromous migration. The annual ring of otolith characters analysis showed the bright and dark belt in the otolith match with the low and high Sr/Ca ratio areas well. It revealed that Coregonus ussuriensis migrate seasonally. Some species migrate to seawater in summer and return back to freshwater in winter regularly, and other species may not have significant regularity. The time of in fresh water and sea water is inconsistent. This study first reported the migratory characteristics of Coregonus ussuriensis, which can provide an important basis for further study on the life history.