Coastal Seawater Temperature during Early Ocean Life of Chum Salmon Measured by Satellite Remote Sensing and Its Effect on Their Return Rates

• Main Authors: Yasuyuki Miyakoshi, Mitsuhiro Nagata, Makoto Fujiwara, In Eastern Hokkaido
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Satellite remote sensing; sea surface temperature; return rate; chum salmon All correspondence should be addressed to Y. Miyakoshi; Nagata; Okhotsk; okhotsk sea
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.522.9563; http://www.npafc.org/new/publications/Technical Report/TR7/Miyakoshi (Coastal).pdf

Many chum salmon populations are currently maintained by hatchery program in Japan. Egg-to-fry survival is improved by the hatchery technologies, and the early marine phase is thought as a critical period for hatchery-reared chum salmon when the mortality is highly variable. Recent researches in the Abashiri Bay, eastern Hokkaido, reported that the distribution of juvenile chum salmon shortly after ocean entry was strongly affected by coastal environmental conditions (Nagata et al. 2005; Miyakoshi et al. 2007), and ocean conditions greatly varied among years (Sawada et al. 2007). We hypothesized that coastal seawater temperature affected the distribution and survival of juvenile chum salmon in this region. The satellite remote sensing has been developed as an effective tool in oceanography research (Laurs and Polovina 2000). We began a study using the satellite remote sensing to analyze the relationship between coastal sea surface temperature (SST) and return rates of chum salmon stocked along the coast of the Okhotsk Sea, eastern Hokkaido. The AVHRR/NOAA data (spatial resolution: 9 km, eight-day composite) distributed by NASA JPL PO-DAAC PATHFINDER database were used to measure SST in the coastal areas. The maximum SST were extracted from 9 coastal boxes (0.5 ° × 0.5°), consecutively spaced at 0.5 ° latitudinal intervals between 41.5°N and 46.0°N in the coastal waters of the Sea of Japan and 6 boxes, consecutively spaced at 0.5 ° longitudinal intervals between 142°E and 145°E in the coastal waters of the Okhotsk Sea (Fig. 1). Each box covers an area within approximately 40 km