Sea surface temperature measured by satellite remote sensing and its effect on the return rate of chum salmon in the eastern region along the Okhotsk Sea
2007
Miyakoshi, Y.(Hokkaido. Fish Hatchery, Eniwa (Japan)) | Nagata, M. | Saitoh, S.
Chum salmon Oncorhynchus keta returning to Hokkaido is currently reproduced by intensive hatchery programs. Early marine life is thought to be a critical period when the mortality of the juvenile chum salmon is high, and the coastal environment, as well as the fish quality, is a factor affecting the success of the hatchery programs. This study examined the effects of a number of juveniles released, the mean weight of the juveniles at release, and the coastal sea surface temperature (SST) on return rate of chum salmon in the eastern region of the Okhotsk Sea coast, off eastern Hokkaido, from 1991 to 2001. Coastal SST was measured using satellite remote sensing (NOAA/AVHRR). The timing at which SST first reached 8 deg C and the mean SST from 25 May to 1 June had significant effects on the return rates of chum salmon; i.e., the higher the coastal SST in late May, the higher the return rate. This indicates that the coastal SST during the short period when hatchery-raised chum salmon migrate to the ocean would be a critical factor determining the survival of chum salmon released in the eastern region of the Okhotsk Sea coast. The effect of fish size was insignificant within the range from 0.92 to 1.17 g in this study, although the mean size of juvenile chum salmon released is gradually increasing because rearing facilities are bringing improvements.
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