1. Distribution and growth rates of Japanese jack mackerel Trachurus japonicus larvae relative to oceanographic conditions in the northern Satsunan area, southern Japan.
- Author
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GEN KUME, KEI NAKAYA, TSUTOMU TAKEDA, MUTSUO ICHINOMIYA, TOMOHIRO KOMORITA, AKIMASA HABANO, FUMIHIRO MAKINO, MASAFUMI KODAMA, and TORU KOBARI
- Subjects
ALGAL blooms ,MACKERELS ,LARVAE ,PREY availability ,SPRING ,LOW temperatures ,APOSTICHOPUS japonicus - Abstract
The northern Satsunan area, comprising the mouth of Kagoshima Bay and Osumi Strait, is an important spawning and nursery ground for Japanese jack mackerel Trachurus japonicus in Japan. Upwellings frequently occur at the mouth of the bay during winter and spring, and the consequent nutrient supply promotes phytoplankton blooms. This study examined how T. japonicus utilizes upwelling (Kagoshima Bay) and non-upwelling areas (Osumi Strait) as larval nursery grounds. Densities and growth rates (measured as the average width of the last three otolith increments) of T. japonicus larvae in both areas were compared to determine the upwelling influence on nursery ground formation. The mouth of the bay had lower temperature and salinity but higher chlorophyll-a concentrations and prey density than that of the strait. Densities of larvae were consistently higher in the bay than in the strait, indicating that the main nursery of T. japonicus is formed in Kagoshima Bay. No significant differences were observed in the growth rates of larvae among areas, suggesting that lower temperatures and prey availability are growth limiting factors in the mouth of the bay and the strait, respectively, and the Osumi Strait could also provide a favorable nursery area. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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