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Abstract-Fish species of the Middle Atlantic Bight (MAB) continental shelf are well known; however, species occupying hard-bottom habitats, particularly on the outer shelf, are poorly documented. Reef-like habitats are relatively uncommon on the MAB shelf; therefore, shipwrecks may represent a significant habitat resource. During fall 2012 and spring 2013, 9 sites (depths: 42-126 m) near Norfolk Canyon were surveyed by using remotely operated vehicles. One site consisted of sand bottom, one consisted of predominantly natural hard bottom, and 7 sites included 8 large shipwrecks. Of 38 fish taxa identified, 33 occurred on hard bottom and 25 occurred on soft substrata. Fourteen fish taxa occurred almost exclusively on hard bottom, and 6 species were observed only on soft bottom. The most abundant taxa, especially on reef habitat, were the chain dogfish (Scyliorhinus retifer), a scorpionfish (Scorpaena sp.), the yellowfin bass (Anthias nicholsi), the red barbier (Baldwinella vivanus), the black sea bass (Centropristis striata), unidentified anthiine serranids, and the deepbody boarfish (Antigonia capros). Depth, location, and season did not significantly influence fish assemblages. Fish assemblages on natural and artificial hard-bottom habitat were similar but significantly different from soft-bottom assemblages. Deep-reef fishes of the southern MAB may be constrained by zoogeography, depth, and inadequate habitat-limitations that could increase their vulnerability.

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This paper describes a study that integrated geographic information system (GIS) habitat mapping, habitat sensitivity analysis, and direct observational data to develop an efficient means of locating shallow water seafloor features warranting environmental protection during seismic operations off northern Mozambique. Data collected during the study were then used to develop a mitigation plan to minimize potential impacts associated with proposed geophysical survey activities. This study combined proven survey techniques for rapid assessment and large-scale mapping of sensitive seafloor features. Preliminary seafloor habitat categorization and mapping of the project area was conducted using high-resolution satellite imagery and a review of relevant published scientific literature. An operation-specific environmental sensitivity index (ESI) was applied to habitat types, and selection criteria were developed for habitats warranting environmental protection (sensitive habitats) from proposed geophysical survey activities. Sensitive habitats were protected from potential impacts from the seismic sound source by mitigation buffers. A subsequent field survey, consisting of a combined side-scan sonar survey of selected geophysical survey lines and rapid assessment groundtruthing of selected seafloor features, was conducted over a 21-day period, surveying 250 km of seafloor in water depths between 2 and 15 m. The side-scan sonar data were reviewed during collection to identify seafloor features that potentially met sensitive habitat criteria. The locations of seafloor features of interest were obtained for subsequent examination by diver scientists utilizing rapid assessment methods for selection criteria verification. Seventy-nine targets were selected for examination during the field survey. The results of the field survey were used during the design of the geophysical survey, with protective areas placed around sensitive habitats. The study demonstrates an integration of survey techniques that collectively provide a time-efficient and cost-effective means to identify and map environmentally sensitive shallow-water seafloor features within a large and environmentally complex geographical area. This study additionally presents the application of an operational-specific ESI based on habitat characteristics which are sensitive to impact producing factors associated with offshore oil and gas exploration activities. This combined technical approach is a practical means to minimize environmental impact while meeting industry engineering and logistic constraints.