Salvador Zarco-Perello

Rabbitfishes (Siganidae) are common members of coastal and estuarine fish assemblages throughout the tropical Indo-Pacific, where they contribute to key ecological processes and ecosystem goods and services. In this review, we summarise current knowledge of the phylogeny, biogeography, life history, habitat associations, feeding ecology, fisheries and aquaculture production of rabbitfishes (Siganidae). Rabbitfishes, which consist of 29-32 species within the single genus Siganus, display remarkable diversity of biological traits that make them unique from other families of herbivorous fishes. Their tolerances to environmental conditions and plastic life history characteristics have allowed them to colonise diverse ecosystems, expand their ranges to higher latitudes, emerge among the most important consumers of macroalgae and seagrass, sustain high intensity fisheries and be very promising for the aquaculture industry. While research on rabbitfishes has started to highlight their importance, further biological and ecological research is needed on more species across different spatial and temporal scales to better understand their relevance for ecosystem functions, their responses to disturbances and the sustainable harvesting of wild populations and aquaculture production.

Climate change is causing poleward expansions of species. Notably, the rabbitfishes (Siganidae) Siganus rivulatus, Siganus luridus and Siganus fuscescens are spearheading the range-expansion of tropical herbivorous fishes into the Mediterranean Sea, Western and Eastern Australia, and Japan. Their range-expansion success is likely due to their plastic biological traits, such as adjustments in phenology, fecundity, habitat associations, and diets, making them highly competitive under a diverse set of environments. Their expansion has led to increased consumption of temperate habitat-forming macrophytes (e.g. Ecklonia spp. and Cystoseira spp.). In Japan, aggregations of rabbitfishes exceeding 500 individuals have been linked to kelp deforestation. Transplantation experiments have shown that rabbitfishes can readily consume solitary adult and juvenile kelps, potentially maintaining canopy-free states. Despite these negative impacts, rabbitfishes have positively influenced local economies, becoming important catches in recreational and commercial fisheries, especially in the eastern Mediterranean Sea, where catches reach hundreds of tonnes valued at millions of euros annually. As climate change progresses, integrating tropical herbivorous fishes in management strategies will become crucial for temperate reefs. Future solutions should include cost-benefit analyses of the ecological and social impacts of range-expansions, particularly considering kelp forests resilience to thermal stress.