Relation of Fish Size and Growth Rate to Migration of Spring Chinook Salmon Smolts

Abstract

We examined the relation of size and growth rate to downstream migration in yearling spring chinook salmon Oncorhynchus tshawytscha. A group of juvenile chinook salmon was graded by size into small and large categories; half the fish in each category were reared at an elevated temperature beginning in mid‐February, resulting in four distinct treatment groups: large–warm, large–cool, small–warm, and small–cool. Fish from warmwater treatment groups displayed significantly higher growth rates through the spring than coolwater groups. Fish were released into a natural creek on two dates (25 March, release 1 and 12 April, release 2), and downstream movement was monitored. For each release, fish that migrated past a weir within the first 5 d postrelease had significantly higher spring growth rates than fish that did not migrate within that period. A similar comparison of release length to migration demonstrated significant differences only in release 2. Also for release 2, fish from the large–warm and small–warm treatment groups were recovered in higher proportions than fish from large–cool and small–cool groups. These results indicate that fish with relatively higher spring growth rates moved downstream sooner than fish with relatively lower growth rates. Furthermore, smolt size and migration were related with larger fish moving downstream sooner than smaller fish; however, this relation was weaker than that found between growth rate and migration.

The Influence of Hatchery Rearing Practices on Salmon Migratory Behavior: Is the Tendency of Chinook Salmon to Remain within Puget Sound Affected by Size and Date of Release?

“…Size at release may also affect migration behavior, as larger smolts tend to migrate earlier or faster than smaller ones in freshwater systems (Ewing et al 1984;Giorgi et al 1997;Beckman et al 1998 smolt size on early marine migration patterns. In the Baltic Sea, larger Atlantic salmon smolts migrated shorter distances than smaller smolts (Kallio-Nyberg et al 1999;Jutila et al 2003;Saloniemi et al 2004).…”

Wild chinook salmon survive better than hatchery salmon in a period of poor production

“…A number of studies (Bilton et al 1982;Bilton 1984;Ward and Slaney 1988;Martin and Wertheimer 1989;Ward et al 1989;Henderson and Cass 1991;Beckman et al 1998;Friedland et al 2009) have shown that larger juvenile Pacific salmon survive better in the early marine environment than smaller individuals. Throughout our study, hatchery fish were consistently larger than the better surviving wild chinook salmon.…”

Quantitative trait locus analysis of hatch timing, weight, length and growth rate in coho salmon, Oncorhynchus kisutch

“…However, when predation is density dependent, early development and corresponding high growth rates as fry may increase an individual's exposure to predation risk and result in lower fitness (Sundstrom et al, 2005). In chinook salmon, juvenile growth rates are also positively correlated with the age and timing of smoltification, the physiological process of adapting to salt water (Beckman and Larsen, 1998), and with increased marine survival during the first winter at sea in coho salmon (Beamish et al, 2004). In contrast to these findings, a study in Atlantic salmon showed a negative correlation between pre-smolt size and post-smolt size, suggesting that the adaptive benefit of size varies across ages and species (Einum et al, 2002).…”