북태평양 연어 이석의 안정동위원소와 미량원소 분석을 통한 회유경로 추정

Abstract

To understand the migratory history of chum salmon in the North Pacific Ocean, we conducted chemical analyses of otoliths. We obtained salmon otoliths from 4 places along the Asian and North American coasts during the 1997-1999 spawning seasons. Stable isotopes (O and C) and trace elements (calcium, strontium, and zinc) were determined/compared with respect to region and life history. The O values of Asian salmon appeared higher than North American salmon, while the C isotope showed opposite patterns over three consecutive years. The high O and low C values of Asian salmon may represent a lower temperature and productivity of ocean habitat than North American salmon. Stable isotope values increased with age, showing a high correlation with salmon size. Such differences in stable isotope values indicate different migration routes and habitat distributions with respect to originations and life stages. Trace elements of otolith were examined by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Sr/Ca ratios, an indicator of salinity, were low during the freshwater stage, increased suddenly at a certain point, and oscillated periodically to a margin corresponding to the year rings. These oscillations might reflect the movement of fish within salinity gradients between onshore/offshore or north/south migrations during their ocean life period. Zinc profiles also oscillated and corresponded to the annual growth rings. However, the profiles of Sr and Zn oscillated oppositely after salmon migrated to saline water and the zinc uptake declined toward the rim of the otolith while strontium uptake increased.