Non-commercial Shore-based Fishing Estimated Average Annual Catch of Reef Fish, 2004-2013 - Hawaii

Nearshore fisheries in the Main Hawaiian Islands encompass a diverse group of fishers using a wide array of gears and targeting many different species. Communities in Hawaii often rely on these fisheries for economic, social, and cultural services. However, the stress from overfishing can cause ecosystem degradation and long-term economic loss. This layer represents the average annual catch of reef fish by non-commercial shore-based fishing methods. Average annual catch at the island scale from 2004-2013 was estimated from Marine Recreational Information Program (MRIP) combined fisher intercept and phone survey data (McCoy et al., 2018). These island-scale estimates were spatially distributed offshore by combining two different proxies for shoreline accessibility (terrain steepness and presence of roads) while accounting for marine protected areas (MPAs) and de facto MPAs (e.g., military danger zones) where access is restricted. This layer's spatial footprint aligns with the inshore commercial reporting blocks for commercial fish catch reporting to the State of Hawaii Department of Aquatic Resources (DAR). This layer is the sum of the three final gear-specific non-commercial shore-based Ocean Tipping Points (OTP) rasters (line, net, and spear).

Slope of the shoreline was calculated in degrees using a USGS 10-m Digital Elevation Model (DEM). Topologically Integrated Geographic Encoding and Referencing (TIGER) road data from the US Census Bureau were used to classify the presence and type of roads. Attributes for slope and road accessibility were then combined into a single accessibility criterion. A weighting scheme was created that assumes easily accessible shorelines with flat slopes and paved public road access have the highest catch and that catch decreases incrementally with level of accessibility. Any combination that includes no accessibility due to steep slopes received a zero weight and therefore zero fishing. Weights sum to 1 for each island. These weights were then multiplied by the MRIP island-scale estimates of annual catch at each coastal point, for three shore-based gear types: line, net, and spear. For line fishing, catch was extended offshore 200 m. For net fishing, catch was extended offshore to the 20-ft depth contour with a maximum distance from shore of 1 km. For spear fishing, a logistic decay function was used so catch decreases with depth to 40 m or a maximum distance of 2 km from shore. Catch in full no-take MPAs were set to zero and other areas with restricted access were reduced according to expert input and local knowledge.

Final pixels values are in units of kg/ha such that the sum of all pixels for each island is equal to the estimates of average annual catch from McCoy et al. (2018). Units, pixel size, and grid alignment are consistent with all other OTP fishing layers so that they can be compared directly or added together for various uses.