Native bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix populations in the Pearl River are threatened by Yangtze River introductions as revealed by mitochondrial DNA.

TLDR: To preserve the native genetic diversity, stocking of non-native fingerlings should cease immediately and native Pearl River bighead and silver carp fish farms should be established, as this research demonstrates the danger to native biodiversity across China.

Abstract: Bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix have been two economically important aquaculture species in China for centuries. In the past decades, bighead and silver carp have been introduced from the Yangtze River to many river systems in China, including the Pearl River, in annual, large-scale, stocking activities to enhance wild fisheries. Nonetheless, few studies have assessed the ecological or genetic impacts of such introductions on native conspecific fish populations. An mtDNA D-loop segment of 978 bp from 213 bighead carp samples from 9 populations and a 975 bp segment from 204 silver carp samples from 10 populations were obtained to evaluate genetic diversity and population integrity. Results from a haplotype network analysis revealed that most haplotypes of the Pearl River clustered with those of Yangtze River origin and only a small proportion were distinct, suggesting that both the native Pearl River bighead and silver carp populations are currently dominated by genetic material from the Yangtze River. The genetic diversity of Pearl River populations is high in both species because of this inter-population gene flow, but the diversity of native Pearl River populations is low. To preserve the native genetic diversity, stocking of non-native fingerlings should cease immediately and native Pearl River bighead and silver carp fish farms should be established. This research demonstrates the danger to native biodiversity across China because of the substantial, ongoing stock-enhancement activities without prior genetic assessment.

Figures

FIGURE 2 The haplotype network of bighead carp Hypophthalmichthys nobilis 718 based on D-loop sequences. The arabic numerals near the dash line mean number of 719 mutations. Clade II is the native Pearl River genetic signature. Samples from the 720 Yangtze River are coloured blue, samples from the Pearl River are coloured red. 721

FIGURE 1 Map showing the sampling sites of bighead carp Hypophthalmichthys 712 nobilis and silver carp Hypophthalmichthys molitrix in the Pearl River. Refer to Table 713 1 for the abbreviations of populations. The map at the top left corner shows the 714 relative location of the research area in China. 715

FIGURE 3 The haplotype network of silver carp Hypophthalmichthys molitrix based 724 on D-loop sequences. The arabic numerals near the dash line mean number of 725 mutations. Lineage II is the native Pearl River genetic signature. A, B are two 726 sublineages of lineage I. Samples from the Yangtze River are coloured blue, samples 727 from the Pearl River are coloured red. 728

Full text

Li, C., Wang, J., Chen, J., Schneider, K., Veettil, R. K., Elmer, K. R.
and Zhao, J. (2020) Native bighead carp Hypophthalmichthys nobilis
and silver carp Hypophthalmichthys molitrix populations in the Pearl
River are threatened by Yangtze River introductions as revealed by
mitochondrial DNA. Journal of Fish Biology, 96(3), pp. 651-662.
There may be differences between this version and the published
version. You are advised to consult the publisher’s version if you wish
to cite from it.
This is the peer reviewed version of the following article:
Li, C., Wang, J., Chen, J., Schneider, K., Veettil, R. K., Elmer, K. R.
and Zhao, J. (2020) Native bighead carp Hypophthalmichthys nobilis
and silver carp Hypophthalmichthys molitrix populations in the Pearl
River are threatened by Yangtze River introductions as revealed by
mitochondrial DNA. Journal of Fish Biology, 96(3), pp. 651-662. (doi:
10.1111/jfb.14253)
This article may be used for non-commercial purposes in accordance
with Wiley Terms and Conditions for Self-Archiving.
http://eprints.gla.ac.uk/109506/
Deposited on: 04 March 2020
Enlighten – Research publications by members of the University of Glasgow
http://eprints.gla.ac.uk/

1
Native bighead carp Hypophthalmichthys nobilis and silver 1
carp Hypophthalmichthys molitrix populations in the Pearl 2
River are threatened by Yangtze River introductions as 3
revealed by mitochondrial DNA 4
5
Chao Li
1,2
†| Junjie Wang
1
†
| Jiaqi Chen
1
| Kevin Schneider
2
| Radhakrishnan K. 6
Veettil
3
| Kathryn R. Elmer
2
| Jun Zhao
1
7
8
1
Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, 9
Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, Guangdong 10
Provincial Engineering Technology Research Center for Environmentally Friendly 11
Aquaculture, School of Life Science, South China Normal University, Guangzhou 12
510631, China 13
2
Institute of Biodiversity, Animal Health and Comparative Medicine, College of 14
Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, 15
Scotland, UK 16
3
College of Fisheries, Central Agricultural University, Agartala, India 17
18
Correspondence 19
Jun Zhao, Guangzhou Key Laboratory of Subtropical Biodiversity and 20
Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe 21
Aquaculture, Guangdong Provincial Engineering Technology Research Center for 22
Environmentally Friendly Aquaculture, School of Life Science, South China Normal 23
† Chao Li and Junjie Wang made an equal contribution to this work.

2
University. Guangzhou 510631, China 24
Email: zhaojun@scnu.edu.cn 25
26
Funding information 27
This work was supported financially by the Special Fund for Agro-scientific 28
Research in the Public Interest (No.201303048), Key Project of National Science and 29
Technology Basic Conditions Platform Work (No.2005DKA21402) and 30
China-ASEAN Maritime Cooperation Fund (No.CAMC-2018F). Chao Li was funded 31
by a visiting scholarship from South China Normal University, the Guangdong 32
Provincial Government (No. 2018010162) and China Scholarship Council (No. 33
201906750010). 34

3
Abstract 35
Bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys 36
molitrix have been two economically important aquaculture species in China for 37
centuries. In the past decades, bighead and silver carp have been introduced from 38
Yangtze River to many river systems in China, including Pearl River, in annual 39
large-scale stocking activities to enhance wild fisheries. However, few studies have 40
assessed the ecological or genetic impacts of such introductions on native conspecific 41
fish populations. We obtained a mtDNA D-loop segment of 978 bp from 213 bighead 42
carp samples from nine populations and a 975 bp segment from 204 silver carp 43
samples from ten populations to evaluate genetic diversity and population integrity. 44
Results from a haplotype network analysis found that most Pearl River haplotypes 45
clustered with haplotypes of Yangtze River origin and only a small proportion were 46
distinct, suggesting that native Pearl River bighead and silver carp populations are 47
both currently dominated by genetic material from Yangtze River. Genetic diversity 48
of Pearl River populations is high in both species because of this inter-population 49
gene flow, but native Pearl River diversity is low. We propose that, to preserve the 50
native genetic diversity, stocking of non-native fingerlings should cease immediately 51
and native Pearl River bighead and silver carp fish farms should be established. This 52
research demonstrates the danger to native biodiversity across China of the substantial 53
ongoing stock enhancement activities without prior genetic assessment. 54
55
KEYWORDS Bighead carp, Silver carp, Pearl River, Genetic diversity, Domestic 56

4
introduction, Stock enhancement 57

Frequently asked questions

Q1. What are the contributions in this paper?

Li et al. this paper showed that bighead and silver carp are two major commercial species in China, which now rank second and third, respectively, in Chinese freshwater aquaculture production using artificial propagation.