Relationship between zooplankton abundance and the early marine life history of juvenile chum salmon Oncorhynchus keta in eastern Hokkaido,Japan |
| |
Authors: | Toshihiko Saito Ikutaro Shimizu Jiro Seki Kazuya Nagasawa |
| |
Affiliation: | (1) National Salmon Resources Center, Fisheries Research Agency, Sapporo Hokkaido, 062-0922, Japan;(2) Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima Hiroshima, 739-8528, Japan |
| |
Abstract: | Interannual variations in abundance, timing of outmigration from rivers, growth rate and condition of juvenile chum salmon (Oncorhynchus keta) were studied in the Nemuro Strait (eastern Hokkaido, Japan) during 1999–2002 to establish a possible relationship to zooplankton abundance. The otolith microstructure of juveniles was examined each year in late June to determine their time and size at sea entry (i.e., outmigration), and to estimate the early marine growth rates. Salmon outmigration peaked in mid- or late May, which coincided, in three of the four study years, with the peak release of juveniles into rivers within the study area. Abundance, growth rate and condition of fish were higher in 2001, when—compared to other years—smaller fish experienced higher growth rates, coinciding with greater zooplankton abundance for that year. Our results suggest that high zooplankton abundance positively influenced juvenile chum salmon growth and the condition of the fish during their early marine life despite their small size at sea entry. |
| |
Keywords: | Chum salmon Coastal residency Fish condition Growth rate Otolith Zooplankton |
本文献已被 SpringerLink 等数据库收录! |
|