2011 Fiscal Year Final Research Report

Examination a hypothesis "growth rate-dependent recruitment" using an archives of sardine otolith

Research Project

Project/Area Number	22780185
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Single-year Grants
Research Field	General fisheries
Research Institution	Fisheries Research Agency
Principal Investigator	TAKAHASHI Motomitsu 独立行政法人水産総合研究センター, 西海区水産研究所, 主任研究員 (80526989)
Project Period (FY)	2010 – 2011
Keywords	カリフォルニア海流域 / 湧昇 / マイワシ / カタクチイワシ / 資源量変動 / 成長速度 / 耳石
Research Abstract	Growth rate during the early life stages of Pacific sardine Sardinops sagax during 1980-2000s was examined based on widths of otolith growth increments as a proxy of daily somatic growth rate in relation to abundance of recruits and environmental factors. Growth rate during the early juvenile stage(60-90 days after hatching) positively correlated with abundance of recruits and sea surface temperature in summer. Previous studies on Japanese sardine S. melanostictus have demonstrated that abundance of recruits is a positive function of growth rate during the early juvenile stage, which is the growth rate-dependent recruitment hypothesis. The results in this study show that the same hypothesis could be applicable for S. sagax and suggest that increase in temperature during the early juvenile stage enhanced growth and survival rates and consequently increased recruitment of S. sagax in the 1990s.