The use of an ROV in the study of juvenile flatfish

This study shows that some low cost remotely operated vehicles (ROV) can be used effectively to locate juvenile flatfish. Vehicles with cameras that are either close to the sediment or that can focus close to the sediment are necessary to see extremely small fish. Additionally a “tickler chain” or similar device which contacts the sediment and fish, causing the fish to move, is often necessary to see flatfish less than 100 mm in length. Identification to species is difficult for specimens less than 150 mm. Concurrent trawl samples in the area can be used to determine percent species composition. Estimates of juvenile flatfish densities by the ROV generally exceed the catch-per-unit-effort estimated from trawls. An ROV is also an excellent tool for observing small scale spatial variations in habitat type and their effects on flatfish distribution.