Are river protected areas sufficient for fish conservation? Implications from large-scale hydroacoustic surveys in the middle reach of the Yangtze River

Abstract

Background The Yangtze River is the third largest river in the world and suffers from extensive anthropogenic impacts. The fishes in the Yangtze River are essential for the sustainable development of freshwater fisheries and the conservation of aquatic biodiversity in China. However, the fishery resources in the Yangtze River Basin have shown rapid decline due to various human activities. In recent years, nature reserves and germplasm resource reserves have become important means to protect fishes in the Yangtze River. However, nature reserves and germplasm resource reserves that regard freshwater fishes as the main object of protection are not common and have been rarely studied in China. In this paper, a hydroacoustic method and systematic conservation planning tool (Marxan) were combined to evaluate the effectiveness of reserves based on the spatial and temporal patterns of mature fishes in the middle reach of the Yangtze River (MRYR) from 2010 to 2017. Results The hydroacoustic survey results indicated that in the longitudinal direction, low densities of mature fish species were observed in the Jingzhou (S2) and Jianli (S4, S5, S6) sections, whereas high densities of fish were observed in other sections, such as the Yichang (S1), Chenglingji to Huangsangkou (S7–S12), and Hukou (S15) sections. Among the regions preferred by fish, S7, S10 and S12 were non-reserves. No significant difference in mature fish density was observed between the non-reserves and nature reserves, and a similar result was obtained between the non-reserves and germplasm resource reserves. In Marxan, the optimal conservation sites selected for habitat restoration, such as the Chenglingji, Dengjiakou, Zhuankou, Hankou, Yangluo, and Huangsangkou sections, which are located in non-reserves, were identified in the MRYR. Conclusions The Chenglingji, Dengjiakou, Zhuankou, Hankou, Yangluo, and Huangsangkou sections, which are located in non-reserves, play equally important roles in the conservation of fish populations in the MRYR. Our results indicated that further optimization is urgently needed for the currently protected areas in this region. These areas should be designated as reserves, and classification protection mechanisms should be adopted to strengthen the effectiveness of fish conservation in the MRYR.

Comparing fish prey diversity for a critically endangered aquatic mammal in a reserve and the wild using eDNA metabarcoding

“…Our metabarcoding approach detected many fish species that have been documented using traditional sampling practices, implying greater fish species richness than traditional netting has suggested. The Chinese government once banned fishing during the spring fish spawning season in certain areas of the Yangtze River only 81 but now has implemented a complete 10-year fishing ban in key areas of the Yangtze River because of dramatic declines in diversity and abundance of aquatic taxa 82 . The Yangtze River is the largest river in East Asia, and the human population along its watershed exceeds 450 million people 83 .…”

Deep Pools: Ecological Sanctuaries for Steindachneridion melanodermatum, a Large Endemic and Endangered Pimelodid of the Iguaçu River

“…Protected areas are one of the main tools used for the biological conservation of aquatic habitats and species worldwide [48][49][50][51], positively affecting fish productivity in freshwater environments [48]. The higher abundance of S. melanodermatum in the protected area was different from the unprotected area downstream of the Salto Caxias Dam to the upper limit of the Iguaçu National Park.…”

A review of conservation status of freshwater fish diversity in China

“…Existing protected areas of China safeguard 25%–29% of freshwater fish habitats, 16%–23% of freshwater fishes, and 30%–31% of priority conservation areas (Tao et al, 2023). This implies that there is limited representation of existing protected areas for Chinese freshwater fishes (Tao et al, 2023; Xie et al, 2019; Zhou et al, 2016). In the Chang‐Jiang basin, the current protected area network cannot achieve fish protection objectives (Huang et al, 2016; Xie et al, 2019).…”