Conservation measures are essential for supporting biodiversity in areas impacted by human activities. Over the last decade, efforts to rehabilitate fish nursery habitats in ports through eco-engineering have gained attention. While these interventions show promise at a local level such as increased juvenile fish densities on artificial eco-engineered habitats compared to unmodified port environments there has been no comprehensive assessment of their contribution to coastal fish population recovery or their effectiveness relative to traditional conservation measures like fishing regulations. In this study, we employed the ISIS-Fish model, which integrates fish population dynamics with fisheries management, to examine the commercial coastal fish species, white seabream (Diplodus sargus), in the highly artificialized Bay of Toulon. By simulating different rehabilitation scenarios and fisheries management strategies, we provided the first quantitative evaluation of eco-engineered structure deployment in ports, covering 10% and 100% of the available port's linear extent. We compared these rehabilitation outcomes against the effects of enforcing strict minimum catch sizes.

Our findings indicate that while port nursery habitat rehabilitation can contribute to fish population renewal and increase catches, the benefits remain limited when project scales are small, especially when compared to the impacts of strict fishing regulations. However, a synergistic effect was observed when combining nursery rehabilitation with fishing control measures, leading to significant improvements in fish populations and catch yields. This study offers the first quantitative analysis of nursery habitat rehabilitation in ports, highlighting its potential as a supplementary strategy to fisheries management, though less effective on its own than robust regulatory measures.