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 a re 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 s imilar device which contacts the sediment and fish, causing the fish to mov e, is often necessary to see flatfish less than 100 mm in length. Identific ation to Species is difficult for specimens less than 150 mm. Concurrent tr awl samples in the area can be used to determine percent species compositio n. Estimates of juvenile flatfish densities by the ROV generally exceed the catch-per-unit-effort estimated from trawls. An ROV is also an excellent t ool for observing small scale spatial variations in habitat type and their effects on flatfish distribution. (C) 1999 Elsevier Science B.V. All rights reserved.