Fish population and behavior revealed by instantaneous continental-shelf scale imaging

Fish populations in continental shelf environments are instantaneously imaged over thousands of square kilometers and continuously monitored by a remote sensing technique in which the ocean acts as an acoustic waveguide [Science 311, 660–663 (2006)]. The technique, ocean acoustic waveguide remote sensing (OAWRS), has revealed the instantaneous horizontal structural characteristics and volatile short-term behavior of very large fish shoals, containing tens of millions of fish and stretching for many kilometers. The former follows a fractal or power-law spectral process, indicative of structural similarity at all scales. The latter features compressional waves of fish population density that travel roughly an order of magnitude faster than fish can swim. Here we present an overview of OAWRS imagery documenting fish activity over a 2-week period in the Spring of 2003 at the edge of the continental shelf, roughly 200 km south of Long Island, NY. Until now, continental shelf environments have been monitored with highly localized line-transect methods from slow-moving research vessels. These methods significantly undersample fish populations in time and space, leaving an incomplete and ambiguous record of abundance and behavior.