Spatial distribution and reconstruction potential of Japanese anchovy (Engraulis japonicus) based on scale deposition records in recent anaerobic sediment of the Yellow Sea and East China Sea

Abstract

Many studies have revealed that anchovy has exhibited large variability in population size on decadal timescales. However, such works concerning anchovy population are mainly based on short historical catch records. In order to understand the causes of variability in fish stocks (natural and/or anthropogenic) and calibrate the error between catches and standing stocks, it is essential to develop long-term time series of fish stocks from the time when human impacts are minimal or negligible. Well preserved fish scales from sediment record are regarded as useful indicators revealing the history of fish population dynamics over the last centuries. Anchovy scales was first analyzed over the Yellow Sea and East China Sea and the largest abundance was found in the central South Yellow Sea where is regarded as the largest overwintering ground for Japanese anchovy (Engraulis japonicas). Thus in the central South Yellow Sea, two cores covering the last 150 years were collected for estimating fish scale flux. The scale deposition rate (SDR) records show that the decadal scale SDRs were obviously coherent between cores with independent chronologies. The calibration of downcore SDRs to the standing stocks of anchovy further validated that SDR is a reliable proxy to reconstruct the long-term anchovy population dynamic in the central South Yellow Sea where anoxic conditions prevail in the sediment. When assembled with other productivity proxies, it would be expected that SDR could be associated with changes in oceanic productivity and may make a contribution to determine the forcing factors and elucidate the mechanism of the process in future.