Prey Fields and Habitat of Deep Divers: 3D Characterization and Modeling of Beaked and Sperm Whale Foraging Areas

The physical and biological characteristics of the areas inhabited by deep diving odontocetes are poorly understood. Our long term goals are: i) to measure and characterize the biomass in areas and at depths inhabited by beaked and sperm whales; ii) to measure and characterize the physics of these environments; iii) to assemble the characteristics measured (i) and (ii) into a depth integrated, 3- dimensional habitat model; the model will include other dependent and independent data, e.g., chlorophyll and depth, respectively. Our final long term goal is to then apply the habitat model produced to other geographic areas to assess their likelihood as beaked and sperm whale habitat. The primary scientific objective for this year's work was to measure the biological and physical environment in areas both frequently (i.e., "hot spots") and rarely (i.e., "cold spots") utilized by beaked whales in the Tongue of the Ocean (TOTO), particularly on the AUTEC range, Andros, Bahamas. These "hot" and "cold" spots were determined using data from the M3R program (DeMarzio REF). The AUTEC range work was completed in coordination with two other programs, the Behavioral Response Study (BRS) and the Marine Mammal Monitoring (M3R) at AUTEC. The R/V Roger Revelle possesses specialized sampling gear that provided a unique technical capabilities, specifically the Hydrographic Doppler Sonar System (HDSS), which is a one of a kind Doppler current profiling system capable of measure current directions and velocities to approx. 1000 meters depth. The technical objectives were: i) to measure the biomass in the TOTO in a representative way so that the biomass in areas not actually sampled could be accurately extrapolated by the habitat modeling; ii) to take physical oceanographic measurements integrated with biological sampling; iii) to compare the deep diving odontocete echolocation activity on the AUTEC range with our measurements of the biological and physical environment.