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SONAR: Mapping Fish Under Pier Structures

Dr. Thomas M. Grothues and Dr. Kenneth W. Able of the Institute of Marine and Coastal Sciences, Rutgers University, are working in the lower Hudson to examine the effects of piers on fish populations. Prior efforts have focused on small benthic fishes but there has been little effort on larger pelagic fishes because of the difficulty of sampling for them in the complex habitats under and around piers. The development of new acoustic imaging technology (Dual Frequency Identification Sonar, DIDSON) has made dark and turbid environments available for visual-style census methods.

These examples show sonar footage recently taken at Pier 40. The first video displays a school of small fishes, possible Menidia mendia, in the second video you will see a school of large stripped bass, Morone saxatilis. The videos are sequential and both the striped bass and forage fish co-occur at this location under the peir.