Hudson Canyon: Multi-Species Habitat Complexes as a Geographic Priority

Hudson Canyon, ~185 km southeast of New York City, is the largest eastern U.S. submarine canyon and a fisheries “hot spot”.  Its vicinity yields commercial and recreational catches including squid, butterfish, monkfish, whiting, black sea bass, fluke, red hake, tilefish, lobster, deep sea red crab, tunas and billfishes. It also supports a biodiverse fauna and may, like other east coast canyons, harbor sensitive deepwater corals and sponges.  Oil and gas have been demonstrated there.  Anticipating interest in Marine Spatial Planning, spatial management of fisheries, and deep corals and sponges, we undertook a study of benthic habitats in Hudson Canyon that included assembly of existing data plus field work: acoustic mapping, visual ground-truthing, hydrographic, sedimentological, and trawl data collections.  Acoustic techniques included multibeam sonar mapping performed using the Autonomous Underwater Vehicle “Eagle Ray”, producing ultra-high resolution (~1 m) in all water depths.  Trawling was performed with 11 m otter and 2 m beam trawls to capture a wide variety of demersal nekton and benthic megafauna in every season.  Visual ground-truthing and sediment collection were accomplished with the USGS drift vehicle “SeaBOSS” with video and stills cameras and grab sampler.  Hydrographic sampling included Conductivity-Temperature-Depth casts and water sampling for dissolved methane analysis.  Products to date include bathymetric, backscatter, and slope maps for about two thirds of the shelf portion of the canyon on scales relevant to the distribution of fishes and megabenthos, and databases for catch, hydrographic, and visual data.  Analysis of data thus far has revealed a complex of geological structures and hydrological patterns that provide a wide range of physical habitats within a relatively small area.  Among unanticipated findings were marked asymmetries in bathymetric morphology and sediment distribution between opposing walls of the canyon as well as large differences up- and down-canyon.  There is evidence for a methane-based chemosynthetic contribution to energy production and to creation of hard bottom habitats, evidence of gravel beds and outcrops of semilithified clay and/or rock deep in the canyon that may serve as the basis for deepwater coral and sponge communities.  Work proceeds on the development of a habitat classification model based on the NOAA Coastal and Marine Ecological Classification Standard to extend physical habitat distributions beyond very limited visual coverage, development of habitat suitability models for fisheries species, and further field work to cover portions of the canyon not yet mapped or characterized.