2012 Fiscal Year Final Research Report

Evaluation of the stock enhancement of chum salmon inJapan using stable isotope retrospective analysis.

Research Project

Project/Area Number	22580209
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	General fisheries
Research Institution	Kitasato University
Principal Investigator	HAYASHIZAKI Ken-ichi 北里大学, 海洋生命科学部, 准教授 (80208636)
Project Period (FY)	2010 – 2012
Keywords	水産資源 / 資源変動 / 環境変動 / 安定同位体 / サケ
Research Abstract	Chum salmon population in Iwate prefecture has declined in catch for these years, although the numbers of juvenile release remained constant. To elucidate the cause of such decrease, stable isotope ratios of fish scales of chum salmon were measured. As results, carbon and nitrogen stable isotope ratiosof muscle and marginal parts of fish scales are positively correlated. This finding suggested fish scales remain stable isotopic signature of pray items. The carbon and nitrogen stable isotopic signatures of second year in oceanic life stage were lower for both Iwate and Hokkaido populations. This finding suggested Japanese chum salmon might have depended on lower level of food web as food items at relatively early stage in its life history.