Effect of artificial fish nest placement on spawning site preference and reproductive efficiency in reservoir fish with adhesive and demersal eggs.

Artificial fish nests are common tools in fisheries management, providing spawning grounds to enhance the size and diversity of fish populations. This study aimed to explore the effects of deployment locations on the reproductive efficiency and preferences of fish with adhesive and demersal eggs using artificial nests. Floating artificial nests were deployed in three regions (upstream, midstream, and downstream) of a reservoir in Zhejiang, China, at locations with three topographical types: steep slope (reservoir shore, slopes > 60°), gentle slope (reservoir shore, slopes < 30°), and confluence (middle thread of channel). The quantity, viability and species of eggs in artificial nests were recorded throughout the fish reproductive cycle. The mean density of viable eggs in artificial nests in the midstream region (1176 ± 448 ind./m) was significantly higher than that in the downstream (477 ± 167 ind./m) and upstream regions (350 ± 148 ind./m). The survival rate of fish eggs in the gentle slope area (56.94 ± 11.97%) was significantly lower than that in the confluence (79.80 ± 6.20%) and steep slope areas (74.47 ± 11.40%). Different fish groups respond uniquely to environmental factors. We suggest that the construction and implementation of artificial nests should be based on the differences in upstream and downstream water bodies, as well as the specific ecological requirements of target fish species. Management practices should focus on site-specific environmental monitoring and adapt nest placement to optimize conditions for different species. Furthermore, future research should aim to develop predictive models that integrate environmental factors and species needs, providing a more robust basis for artificial nest placement and fisheries management.