Supporting Evidence for the “Ten-Year Fishing Ban”: Different Modes of Fishing and Pollution Induce a Fish Diversity Decline between the Pearl River and Its Estuary

Abstract

To settle the emerging debate on whether a "ten-year fishing ban" is too long or an annual fishing moratorium is enough for fish resource restoration in the Yangtze River, a long-term comparison between the 1980s and the 2020s in the Pearl River was performed. Significant declines in fish biodiversity were determined among both the Pearl River and its estuary over the past decades. The trophic level increased from 4 to 5 in the estuary, whereas it remained at 4 in the Pearl River. Interestingly, an opposite trend in interspecies networks of fish was observed between the Pearl River and its estuary. A reduced density and increased links were detected in the Pearl River as its interspecies networks became complex, which was in contrast to that in the estuary. Furthermore, fishing and pollution were both confirmed to participate in the fish biodiversity decline in the Pearl River, whereas pollution was the dominant factor inducing the fish biodiversity decline in the estuary. Our case indicated that an annual fishing moratorium is not enough for fish resource restoration and supports the strategy of "ten-year fishing ban". Moreover, pollution should also be brought under control so that we can facilitate fish resource restoration.

Effects of a Fishing Ban on the Ecosystem Stability and Water Quality of a Plateau Lake: A Case Study of Caohai Lake, China

“…This phenomenon can be attributed to the relatively small size and shallow nature of Caohai Lake, where populations at higher trophic levels tend to exhibit relatively lower biomasses. This observation aligns with findings reported for the West River in the Pearl River Basin [13].…”

“…This phenomenon can be attributed to the relatively small size and shallow nature of Caohai Lake, where populations at higher trophic levels tend to exhibit relatively lower biomasses. This observation aligns with findings reported for the West River in the Pearl River Basin [13]. The transfer efficiencies among the trophic levels in the Caohai Lake ecosystem before and after the fishing ban are summarized in Table 5.…”

“…These findings are consistent with those of a study conducted in the Pearl River Basin, which documented a shift from submergedplant dominance to algal dominance in the ecosystem. This transition resulted in a significant increase in the calculated total net primary production [13]. Furthermore, in Er-…”

“…These bans serve not only to safeguard spawning populations and juvenile fish but also to promote a balanced ecological equilibrium among various fish species [12]. However, research in the Pearl River Basin has uncovered potential ecosystem shifts [13]. After the implementation of fishing bans, phytoplankton have emerged as the dominant primary productivity source, displacing submerged aquatic plants and impacting the West River's ecosystem [13].…”

“…However, research in the Pearl River Basin has uncovered potential ecosystem shifts [13]. After the implementation of fishing bans, phytoplankton have emerged as the dominant primary productivity source, displacing submerged aquatic plants and impacting the West River's ecosystem [13]. Consequently, the extent to which long-term fishing bans facilitate the recovery of the ecosystem structure and function remains to be elucidated.…”