47 Protected Species Hotspots
Description: Integrated persistent annual hotspots derived from at-sea observations of seabirds, cetaceans and sea turtles collected on systematic ship and aerial surveys
Found in: State of the Ecosystem - Mid-Atlantic (2022+), State of the Ecosystem - New England (2022+)
Indicator category: Extensive analysis, not yet published, Database pull with analysis
Contributor(s): Timothy P. White timothy.white@boem.gov
Data steward: Timothy P. White timothy.white@boem.gov
Point of contact: Timothy P. White timothy.white@boem.gov
Public availability statement: Source data are publicly available. Please contact Timothy White for more details.
47.1 Methods
Individual hotspot richness maps represent annual persistent hotspots of 71 species and also common taxa challenging to identify to the species level on at-sea surveys but whose abundance and spatial patterns significantly contribute to richness and diversity on the Atlantic EEZ (seabirds, n = 49; marine mammals, n=18, turtles, n= 4). The integrated maps represent very high densities and very high persistence; however, one or both parameters can be adjusted to identify other important locations, for example, to reveal areas of high density and moderate persistence. Individual species-specific hotspots were defined using the 75th percentile of the annual density distribution on gridded segmented transects. This density threshold identified locations of enhanced abundance on daily gridded transects. Persistence probabilities for each grid cell were quantified by summing the number of times a given cell was classified as a hotspot to produce a spatial organization of hotspots coupled with persistence probabilities ranging from 0 to 1. These probabilities were thresholded also using the 75th percentile to locate highly persistent areas of single-species hotspots and summing across each grid cell to resolve multi-species hotspots. The minimum survey effort for each cell in the grid was five days.
47.1.1 Data sources
The annual persistent hotspot maps presented here of seabirds, cetaceans, and sea turtles were derived from observations and survey effort archived in publically available databases such as the Bureau of Ocean Energy Management’s Northwest Atlantic Seabird Catalog; NOAA Northeast Fisheries Science Center’s (NEFSC) AMAPPS database; NEFSC’s Right Whale Aerial Survey database; and the MassCEC/NEAq database of cetacean and turtle surveys. Observer-based programs use two main survey methods to estimate densities at sea from ships and aircraft 1) the strip-width method (White and Veit (2020)) and 2) distance sampling Palka et al. (2017)).
47.1.2 Data analysis
All detailed data processing steps are not currently included in this document, but general steps are outlined. Species-specific persistent hotspots were computed with observations and survey effort collected on ship and aerial surveys from 1978-2020. Species-specific hotspots were derived with daily timesteps on 10 x 10 km grids covering the Atlantic EEZ. Hotspot probabilities (i.e., persistence) were derived by summing the number of daily hotspots divided by the number of time steps (Gende and Sigler (2006)), which produced a continuum of probabilistic hotspots ranging from 0 to 1 across a final species-specific grid. Annual hotspot richness maps were derived by summing the species-specific grid cells with high persistence.
47.1.3 Data processing
Persistent hotspots were computed with the sf and raster R packages.
catalog link https://noaa-edab.github.io/catalog/persistent_hotspots.html