Monitoring shallow benthic fish assemblages in the Lauentian Great Lakes using baited photoquadrats: enhancing traditional fisheries monitoring methods.

Photoquadrats and underwater video surveys are standard non-destructive monitoring methods in marine ecosystems and are becoming more common in freshwater systems. The high water clarity found in most of the Laurentian Great Lakes make them ideally suited for photoquadrat sampling. We compared the effectiveness of baited photoquadrats to monitor benthic fish communities of shallow, littoral habitats of northern Lake Michigan. We compared our results with baited minnow traps, a technique commonly used to monitor benthic fish communities in freshwater ecosystems. Photoquadrats baited with lake trout (Salvelinus namaycush) eggs, the most effective attractant, proved to be an efficient tool for sampling round goby (Neogobius melanostomus) relative abundance and resulted in higher round goby catches than in photoquadrats baited with a commercially available fish attractant or unbaited photoqudrats. This method allowed sites to be surveyed rapidly (requiring <1 h per site), and replicate samples produced data with low variability. In contrast, baited minnow traps produced highly variable catch per unit effort (CPUE) irrespective of soak time. Photoquadrat methods appear to be an improvement over traditional sampling with minnow traps for round goby and may also be better for other nearshore benthic fishes.