North Pacific Anadromous Fish Commission

Technical Report 11

Table of Contents

Environmental Factors Affecting the Survival of Juveniles and Recent Returns of Chum Salmon in the Okhotsk Coast of Hokkaido

Authors:
Yasuyuki Miyakoshi, Hayato Saneyoshi, and Yousuke Koshino

Abstract Excerpt:
The Okhotsk coast of Hokkaido is the principal area of chum salmon, Oncorhynchus keta, production in Japan. In recent years, returns of chum salmon to the Okhotsk coast have been reaching historic highs, although decreases of chum salmon on the other coasts of Hokkaido have been remarkable since 2008 (Miyakoshi et al. 2013). The early marine phase is considered the critical period for the survival of chum salmon, that determines the subsequent number of fish returned. One of the likely causes for the regional difference in return rates is the recent changes in the coastal environment around the time that juvenile salmon migrate into the area (Nagata et al. 2016a). The recent high abundance of chum salmon in the Okhotsk coast should be due to the favorable ocean conditions and successful enhancement program. However, the returns of chum salmon to the Okhotsk coast of Hokkaido have decreased since 2014; with extreme low returns of the 2010, 2012, and 2013 brood year classes were observed.

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DOI:
https://doi.org/10.23849/npafctr11/44.45

Citation

Miyakoshi, Y., H. Saneyoshi, and Y. Koshino.  2018.  Environmental factors affecting the survival of juveniles and recent returns of chum salmon in the Okhotsk coast of Hokkaido.  N. Pac. Anadr. Fish Comm. Tech. Rep. 11: 44–45.  https://doi.org/10.23849/npafctr11/44.45