A crowded ocean: Including biological monitoring results in marine spatial planning efforts

Abstract

We have conducted collaborative research projects in coastal mid-Atlantic waters, including summer aerial surveys, sea turtle telemetry studies, opportunistic whale sightings data collection, and a ship traffic characterization study. Additionally, we respond to live and dead strandings of cetacean and pinniped species for which there are no density or tagging data in the area, but where we have regular documentation of occurrence in the stranding record. Compiling these data into a single spatial analysis allows us to better: 1) understand human and wildlife use of areas, 2) plan for development, and 3) predict potential conflicts. Our tagging and sighting projects can be used to understand species habitat use. For the tagging data, we included a maximum of one location data point per day from five satellite-tagged loggerhead sea turtles (Caretta caretta) from July-October in 2011. From this analysis, we calculated that 71% (64 out of 118) of the data points were within 30 nm of one or more mid-Atlantic Wind Energy Areas (MAWEAs). During 2011, a total of 14,576 km of aerial survey transits resulted in 1,572 sea turtle sightings, with 1,122 animals (71%) located within 30 nm of the Virginia WEA. In addition, 49% (227 out of 648) of bottlenose dolphin (Tursiops truncatus) group sightings, representing 57% (1471 out of 2588) individual animals, were within 30nm of MAWEAs. Using photo identification techniques, we documented a minimum of 57 humpback whales (Megaptera novaeangliae) and 5 fin whales (Balaenoptera physalus) in near-shore Virginia ocean waters from December 2011 through February 2012. One major challenge to applying this biological monitoring data in marine spatial planning efforts is the lack of spatial density data for marine mammals and sea turtles, particularly on a regional and seasonal scale. In the U.S. mid-Atlantic region, relatively few survey efforts have occurred, and those that were conducted have been of such broad scale that few, if any, of the less common species were sighted. These results have led to calculated densities of zero or near zero for some species in a region where anecdotally we know that they regularly occur. When these densities are applied to management documents, inaccurate conclusions may be made regarding environmental impact assessments. For example, the 2012 Draft Programmatic Environmental Impact Statement (DPEIS) for the Atlantic OCS Proposed Geological and Geophysical Activities Mid-Atlantic and South Atlantic Planning Areas used marine mammal density calculations to model marine mammal takes from seismic surveys and assign an environmental impact measure to the action. Densities were reported for all marine mammal species with habitat ranges in the area. The DPEIS identifies Zone 20 extending across the continental shelf from Cape Lookout to the Delaware Bay, including Virginia waters. Many of the species have zero or near zero reported densities, but have regular presence in Virginia stranding and sighting records (Table 1). Humpback whales and bottlenose dolphins (Tursiops truncatus) are of particular interest, because both our sighting reports and our stranding data are inconsistent with these densities. A similar problem has occurred in analyses of vertical line and whale co-occurrence that was conducted for the NOAA Fisheries Atlantic Large Whale Take Reduction Team. Lack of formal survey data from the mid-Atlantic region resulted in a model with large areas of zero density, despite extensive anecdotal stranding and sighting records. We propose that a method for determining “minimum density” should be developed and utilized for species with verified anecdotal records, such as stranding data. Then we can better model animal presence, and potential impacts from human activities, for species with inadequate data from formal surveys. The monitoring of anthropogenic activity in marine habitats is also important to predict the cumulative impact of development to populations and species. During our 2008-2009 ship characterization study, we utilized AIS technology to record 323 vessels (18,473km of transits) traveling through the Virginia WEA, representing 30% of all AIS recorded large vessel traffic. Ship traffic rerouting as a result of wind energy development could increase the risk of interactions between wildlife and human activity by potentially displacing whales and ships into smaller, higher-density areas. Commercial fishing and Federal vessel activity are currently unrepresented in AIS datasets, and should be monitored and considered in spatial planning efforts in order to have a complete picture of how offshore development projects will affect all vessel activity. Marine spatial planning is an important tool to mitigate potential conflicts associated with ocean use issues, and both biological monitoring data and human use information are essential for the process to be successful. This analysis indicates that non-traditional sources of data, in addition to data from traditional density surveys, are being used to monitor endangered and protected species and should be included in the spatial planning process to inform management decisions.