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Unselective fishing could reduce fish diversity and homogenize assemblage structure in lakes

Non-selective fishing can reduce fish diversity and homogenize the assembly structure in lakes

Non-metric multidimensional scaling of the relative abundance of species at sampling sites in studied lakes showed that the differences between lakes narrowed over the years. Credit: IHB

Freshwater fisheries are recognized as a major stressor to aquatic ecosystems, often leading to dramatic changes in the structure of natural populations. Freshwater fisheries generally take two forms: intensive fisheries for specific species and non-selective fisheries for whole collections.

Non-selective fishing involves activities that target the entire assemblage rather than specific fish species, size classes or trophic levels. This approach has been widely used in China’s inland waterways for decades, but the implications for biodiversity remain unclear.

Recently, a research team led by Prof. Chen Yushun of the Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences has shown that non-selective fishing can reduce fish diversity and homogenize the assemblage structure in lakes. The study was published online in Water biology and safety

To study the potential effects of non-selective fishing on fish diversity and assemblage structures, the researchers studied fish assemblages in freshwater lakes, including five fishing lakes, one reference lake, and a total of 51 sampling sites, between the time before and after fishing. periods in eastern China from 2017 to 2019. They found different trends in fish collection changes between fishing and reference lakes.

The researchers then assessed the effects of the lake, fishing period and their interactions on fish abundance, biomass and diversity indices. In fishing lakes, they observed fish species richness, abundance, biomass and all three life history strategies (opportunistic, equilibrium and periodic) significantly decreased after the fishing activities were implemented, while opposite trends were observed in the reference lake.

The researchers further tested the differences in fish collections between lakes and between fishing periods. The results showed that the compositional similarity of fish collections between fish lakes increased over the three-year monitoring period.

This study has important implications for the protection of fisheries and biodiversity in China’s inland waters, and may also be applicable to other countries or regions that depend on fish as an important food source, while dealing with overfishing and reduction of the biodiversity. In addition, the understanding of the ecosystem impacts associated with non-selective inland water fishing improved.

Removing planktivorous fish reduces cyanobacterial bloom in a large subtropical highland lake

More information:
Han Liu et al, Reduction of fish diversity and homogenization of assemblage structures in lakes: a case study on non-selective fisheries in China, Water biology and safety (2022). DOI: 10.116/j.watbs.2022.100055

Provided by the Chinese Academy of Sciences

Quote: Non-selective fishing can reduce fish diversity and homogenize assemblage structure in lakes (2022, June 22) retrieved June 22, 2022 from https://phys.org/news/2022-06-unselective-fishing-fish-diversity-homogenize .html

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