Fishing for more than shellfish: a systematic review of fish community monitoring of shellfish reefs

Shellfish reefs, characterized by habitat-forming bivalves, are increasingly recognized as globally significant coastal ecosystems and valuable fish habitats. Shellfish reefs provide structural refugia, foraging grounds, and nurseries for diverse fish communities, including species with socioeconomic value. However, efforts to quantify the value of shellfish reefs as fish habitats are challenged by the limited and fragmented knowledge of published monitoring practices. Here, we systematically assess 116 peer-reviewed studies to provide a global overview of literature evaluating fishes in these ecosystems. Research was unevenly distributed, with 67% of the studies concentrated in the United States, 61% on restored reefs, and 83% focused on oyster reefs. Few studies have directly compared fish communities between natural versus restored, or intertidal versus subtidal shellfish reefs. Methods to quantify fishes varied based on research objectives, tidal zonation, and targeted subsets of the fish assemblages. Gill nets, substrate trays, and underwater video stations were the most common methods, with 44% of studies deploying more than two methods to survey fish communities. Differences in the monitoring methods, research designs, and variables reported were also synthesized and discussed. From this review, we identified knowledge gaps and monitoring trends in fish community assessments that can guide future shellfish reef research and conservation efforts.