Vessel Survey for Abundance and Distribution of Marine Mammals and Seabirds (VSAD)

Marine mammals and seabirds incurred significant injuries throughout the Gulf of Mexico (GOM) as a result of the Deepwater Horizon oil spill. In order to effectively monitor the outcomes of marine mammal and seabird restoration in the Gulf, we need reliable abundance and distribution reference points. One of the principal means by which Trustees document population trajectories of offshore marine mammals is through offshore vessel surveys, such as those conducted through the Gulf of Mexico Marine Assessment Program for Protected Species (GoMMAPPS). In the case of sperm whales, pantropical spotted dolphins, and other focal species (see the Strategic Framework for Marine Mammal Restoration Activities for details), there is a need for additional information to determine if the declines detected in previous GoMMAPPS surveys are continuing, establish reference abundance estimates, and better understand the spatial distribution of these animals to inform future restoration activities (DWH NRDA Trustees 2017a). For example, if the sperm whale population has moved further west as indicated by previous surveys, the Trustees might prioritize vessel strike reduction efforts in the western Gulf.

The last vessel survey conducted under GoMMAPPS ended in October 2018 and there are currently no large whale vessel surveys planned in the GOM. With just over a single year of data documenting the decline and shift, results are difficult to interpret without additional data to evaluate potential trends versus interannual variability. Updated data will help to verify and validate spatial models and will indicate whether or not the recently observed spatial distribution shifts persist through time. For restoration, confirming whether these declines are real will assist in establishing reference points and updating our understanding of spatial distribution, which will impact adaptive management of existing Open Ocean projects and planning for future restoration projects.

For marine mammals, the objective of this MAIP is to collect information on the distribution, density, and abundance of oceanic cetacean stocks and develop seasonally and spatially explicit maps of species density to incorporate into existing spatial density models. Outcomes to measure success will include development of updated seasonal/spatial density maps, updated spatial density models, and a summary report and recommendations for utilizing data to inform restoration

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