Improved quadrat method for fish survey in tide-pools of tidal flats

Accurately determining the species richness and/or abundance using quantitative sampling methods is important for understanding community structures. The quadrat method has been one of the most commonly used quantitative methods for estimating benthic animals in tidal flats. However, it is difficult to implement this method in biodiversity surveys of benthic fishes, as they can move across the quadrat, thus altering the observations. In the present study, we introduced the quantitative sampling method for benthic fishes in tide-pools located in tidal flats by employing an improved quadrat with a net and sinkers. This setup prevented the movement of fishes across quadrats, unlike the conventional quadrat method which allowed the easy movement of fishes. This improved quadrat method can be useful in surveying fish biodiversity in tide-pools in a wide range of tidal flats. The potential advantages of this method include 1) determining the accurate biodiversity of fishes in a tidal flat tide-pool, 2) easily comparing the biodiversity per unit area among multi-sampling sites, and 3) easily increasing the number of quadrats in field surveys. We believe that our improved quadrat method will simplify and promote the study of fishes in tidal flats.