Variations in early life history traits of Japanese anchovy Engraulis japonicus in the Yangtze River Estuary.

Chunlong Liu,Weiwei Xian,Shude Liu,Yifeng Chen

doi:10.7717/peerj.4789

Abstract

Resources of Japanese anchovy (Engraulis japonicus Temminck & Schlegel, 1846) are undergoing dramatic recessions in China as the consequence of intensifying anthropogenic activities. Elucidating the influences of local-scale environmental factors on early life history traits is of great importance to design strategies conserving and restoring the declining anchovy resources. In this research, we studied hatching date and early growth of anchovy in the Yangtze River Estuary (YRE) using information obtained from otolith microstructure. Onset of hatching season and growth rates of anchovy was compared to populations in Japan and Taiwan. In YRE, the hatching date of anchovy ranged from February 26th to April 6th and mean growth rate ranged from 0.27 to 0.77 mm/d. Anchovies hatching later had higher growth rates than individuals hatching earlier before the 25th day. Among populations, hatching onsets of anchovy from the higher latitude were later than populations in the lower latitude, and growth rates of anchovy in YRE were much lower than populations in Japan and Taiwan. Variations in hatching onsets and early growth patterns of anchovy thus provide important knowledge on understanding the adaptation of anchovy in YRE and designing management strategies on conserving China’s anchovy resources.

Highlights

Japanese anchovy (Engraulis japonicus Temminck & Schlegel, 1846) is a widespread fish in the northwest Pacific Ocean with great contributions to fishery resources and ecosystem functions (Zhao et al, 2003; Takasuka & Aoki, 2006; Wan & Bian, 2012)
No significant difference was found in the relationships of Standard length (SL) with D between two stations (p > 0.05), and the SL-D relationship were described by a common regression equation for two populations: SL = 0.386D + 4.87 (R2 = 0.55, p < 0.01)
Despite of the overall similar patterns of increasing growth rates for three groups before the 25th day, significant differences were found in growth trajectories between three groups at each station (Station 29, all p < 0.05; Station 30, all p < 0.05), with anchovy hatching later showing much faster growth (Fig. 3)

Summary

Introduction

Japanese anchovy (Engraulis japonicus Temminck & Schlegel, 1846) is a widespread fish in the northwest Pacific Ocean with great contributions to fishery resources and ecosystem functions (Zhao et al, 2003; Takasuka & Aoki, 2006; Wan & Bian, 2012). Despite of the profound impacts of climatic factors on anchovy resources (Kim & Lo, 2001; Hsieh et al, 2009), local-scale environmental factors (e.g., sea surface temperature and habitat quality) are the key determinants on dynamics of anchovy population, which has been well studied in Japan, Korea and Taiwan (Chen & Chiu, 2003; Takahashi & Watanabe, 2004; Takasuka, Oozeki & Aoki, 2007). In mainland China, the region owning the widest distributions and largest catches of anchovy (Fisheries and Aquaculture Department, FAO, Rome, Italy; available: http://www.fao.org/home/en/), little effort was paid to explore the influence of local environmental factors on anchovy populations (but see Zhu, Zhao & Li, 2007)

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