Impacts of hatchery-reared mandarin fish Siniperca chuatsi stocking on wild fish community and water quality in a shallow Yangtze lake

David A Beauchamp,Mingli Lin,Brendan J Hicks,Chuanbo Guo,Zhongjie Li,Wei Li,Jiashou Liu,Tanglin Zhang

doi:10.1038/s41598-018-29758-z

Abstract

Mandarin fish Siniperca chuatsi, a valuable piscivorous fish, have been stocked into many lakes in China since the 1990s. This study did the first attempt to evaluate the ecological effects of hatchery-reared mandarin fish stocking in the Yangtze River basin lakes. Our study demonstrated a significant change in fish community composition after mandarin fish stocking, but no fish extinction was observed. No significant difference was observed in the total density of 13 forage fish before and after mandarin fish stocking, but the total biomass showed a significant decline after mandarin fish stocking. Significant differences in length-frequency distributions were observed for Carassius auratus, Pseudorasbora parva and Toxabramis swinhonis captured before and after stocking mandarin fish. No significant change in habitat distribution was detected before and after mandarin fish stocking. A marked decline in total nitrogen and a slight decline in total phosphorus were observed while a slight increasing trend for Secchi depth was found after stocking. Our findings suggested that mandarin fish stocking can increase predation pressure on forage fish and subsequently optimize the food web structure. Also, mandarin fish stocking has the potential to improve water quality and may be a feasible strategy to alleviate eutrophication of shallow Yangtze lakes.

Highlights

Stock enhancement is a fisheries management approach involving the release of cultured organisms to increase abundance and yield of natural fish or invertebrate stocks[1]
Our study in Biandantang Lake demonstrated a significant change in forage fish community composition from one with similar proportions of T. swinhonis, H. leucisculus, C. dabryi, C. auratus and P. parva prior to mandarin fish stocking to a community dominated by T. swinhonis after stocking
The observation of reduced species diversity following stocking with a top piscivore is consistent with previous studies for piscivorous fish in North American and European countries[10,11,20,34], but this is the first evidence that mandarin fish stocking exert strong effects on the community structure of wild forage fish in the shallow Yangtze lakes

Summary

Introduction

Stock enhancement is a fisheries management approach involving the release of cultured organisms to increase abundance and yield of natural fish or invertebrate stocks[1]. Direct predation on fish can change the species composition and size structure of the fish community at lower trophic levels and reduce population densities[13,14]. Predators may reduce benthivorous fish, leading to a decrease in suspended material in the water column, thereby increasing Secchi depth[21] Based on this evidence, stocking piscivorous fish in eutrophic lakes is commonly referred to as biomanipulation and is a possible strategy to alleviate eutrophication[19]. We compared the composition, abundance, size structure and spatial patterns of habitat use of wild forage fish before and after mandarin fish stocking in a shallow Yangtze lake, Central China.

Methods

Results

Conclusion