Authors: Seo, Hyunju¹; Kudo, Hideaki¹; Kaeriyama, Masahide²

Source: Environmental Biology of Fishes, Volume 90, Number 2, February 2011 , pp. 131-142(12)

Publisher: Springer

Abstract:

We used multiple regression and path analysis to examine the effects of regional and larger spatial scales of climatic/oceanic conditions on the growth, survival, and population dynamics of Hokkaido chum salmon (Oncorhynchus keta). Variability in the growth of chum salmon at ages 1 to 4 was estimated from scale analysis and the back-calculation method using scales of 4-year-old adults returning to the Ishikari River in Hokkaido, Japan, during 1943-2005. Growth of chum salmon at age 1 was less during the period from the 1940s to the mid-1970s compared to the period from the mid-1980s to the present. On the other hand, growth of chum salmon at ages 2, 3, and 4 has declined since the 1980s. Path analysis indicated that growth at age 1 in the Okhotsk Sea was directly affected by warmer sea surface temperatures associated with global warming. The increased growth at age 1 led directly to higher survival rates and indirectly to larger population sizes. Subsequently, in the Bering Sea, the larger population size was directly associated with decreased growth at age 3 and indirectly associated with shorter adult fork lengths despite the lack of relationships among sea surface temperature, zooplankton biomass, and growth at ages 2 to 4. Therefore, higher growth at age 1 related to global warming positively affected the survival rate of juvenile chum salmon in the Okhotsk Sea. The higher survival rates in turn appear to be causing a population density-dependent effect on growth at ages 2 to 4 and maturation in the Bering Sea due to limited carrying capacity.

Keywords: Chum salmon; Density dependence; Global warming; Growth; Scale analysis; Survival

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s10641-010-9725-7

Affiliations: 1: Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido, 041-8611, Japan 2: Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido, 041-8611, Japan, Email: salmon@fish.hokudai.ac.jp

Publication date: 2011-02-01

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