Could artificial reefs increase access to estuarine fishery resources? Insights from a long-term assessment

Abstract

Artificial reefs (ARs) have been used globally to increase fish stocks, especially for local fisheries, but few studies have addressed the seasonal changes in fish attracted to ARs over extended periods. Bottom gillnets were used twice a year (wet versus dry seasons) to investigate how the composition and structure of fishing resources change over seasons during 20 years in the oldest experimental AR complex deployed in Southeastern Brazil. In total, 74 fish species were caught, and Sciaenidae, Carangidae and Ariidae families were the most representative in both numbers and occurrence. Fish abundance, species richness and biomass varied significantly between AR and reference site (RS), with higher values being recorded in the artificial habitats. Generalized additive models and ANOVA showed a gradual transition over time for the fish assemblages associated with the reef complex, indicating an initial phase primarily dominated by estuarine species, followed by an extended period of attraction by reef-associated fish and many species of commercial interest. The season was identified as the most important factor for the development of fish assemblages in the AR complex. Fish abundance increased gradually towards the 14th year after AR deployment and became more variable thereafter, with the stabilization or a abundance decreasing for some species. Our findings reveal that AR might be locally important for commercial species such as Rhizhoprionodon porosus, Macrodon ancylondon and Isopisthus parvipinnis, and highlight the importance of structurally complex structures as a promising strategy to enhance the attraction of fishery resources.