North Pacific Anadromous Fish Commission

Technical Report 17

Table of Contents

Low Nutritional Status in the Freshwater Phase and Temperature at Seawater Entry Reduce Swimming Performance of Juvenile Chum Salmon

Authors: 
Mitsuru Torao, Yasuyuki Miyakoshi, and Munetaka Shimizu

Abstract Excerpt:
Chum salmon (Oncorhynchus keta) is an important commercial fish in Hokkaido and northeastern Japan, and its resources are maintained by stock enhancement programs (Nagata et al. 2012; Miyakoshi et al. 2013; Kitada 2014). Japanese chum salmon likely experience substantial mortality when entering the sea and reaching the Sea of Okhotsk; however, little is known about the causes of this early mortality. Following their release, juvenile chum salmon spend days to weeks in the river (Hasegawa and Takahashi 2013; Kasugai et al. 2013), and the nutritional condition of individuals decreases during this time (Shimizu et al. 2016). In the salmon of eastern Hokkaido, the adult return rate tends to be low when coastal water temperatures are low, during the early stages of marine life (Nagata et al. 2016). Thus, sea surface temperature (SST) has been implicated as a key factor in determining the distribution and outmigration of chum salmon along the coast. When juvenile chum salmon experience low water temperatures (≤ 5°C) in coastal waters, their movements are restricted and their growth ceases (Miyakoshi et al. 2007; Kasugai et al. 2012). However, it is unclear whether the nutritional conditions of freshwater and SST interact to affect the growth and swimming ability of juvenile chum salmon. The purpose of this study is to elucidate the combined effects of freshwater feeding status and seawater temperature on the swimming ability of juvenile chum salmon under laboratory conditions.

*This is the first paragraph of an extended abstract. Download the full abstract below.

DOI:
https://doi.org/10.23849/npafctr17/58.59.

Citation

Torao, M., Y. Miyakoshi, and M. Shimizu.  2021.  Low nutritional status in the freshwater phase and temperature at seawater entry reduce swimming performance of juvenile chum salmon.  N. Pac. Anadr. Fish Comm. Tech. Rep. 17: 58–59.  https://doi.org/10.23849/npafctr17/58.59.