Reef Fish Fishing

Submitted by ellen on

Nearshore fisheries in the Main Hawaiian Islands encompass a diverse set of fisheries in which multiple gear types are used to harvest reef finfishes and invertebrates, estuarine species, and schooling coastal pelagic fishes. Communities in Hawaiʻi often rely on these fisheries for economic, social, and cultural services. Stress from over-fishing can cause ecosystem degradation and long-term economic loss.

We created a series of fisheries catch data layers for catch of reef finfishes, grouped into three categories of fishing platforms (non-commercial shore, non-commercial boat, and commercial) and three subcategories of fishing gear (line, net, and spear). For all fishing layers we accounted for marine protected areas (MPAs) where fishing is prohibited and de facto MPAs (e.g., military danger areas) where access is restricted. All fisheries catch layers represent average annual catch in units of kg ha-1 yr-1. 

Non-commercial Shore-based Fisheries Catch – We used estimates of average annual catch by platform and gear type at the island scale, from 2004-2013, derived from Marine Recreational Information Program (MRIP) survey data. These island-scale estimates were combined with measures of shoreline accessibility (terrain steepness and presence of roads) to spatially distribute catch offshore around each island. 

Line: Catch was extended 200 m offshore; 

Net: Catch was extended offshore to the 20-ft (6.1-m) depth contour or a maximum distance of 1 km from shore; 

Spear: Catch was extended offshore based on a decay function where catch decreases with depth to 40 m or a maximum distance of 2 km offshore, and assumes the vast majority of catch occurs shallower than 20 m. 

Non-commercial Boat-based Fisheries Catch – We used estimates of average annual catch by platform and gear type at the island scale, from 2004‑2013, derived from Marine Recreational Information Program (MRIP) survey data. In order to spatially distribute catch offshore around each island, we used a function that decays with distance to boat harbors and launch ramps, and weighted the amount of catch out of each ramp/harbor based on the human population within the surrounding 30 km. 

Commercial Fisheries Catch – We used average annual catch of reef fish by gear type over the years 2003-2013 as reported in commercial catch data collected by the State of Hawaiʻi Department of Aquatic Resources (DAR). Commercial catch is reported to DAR in large irregular reporting blocks, by gear and by species. Since it is not possible to distinguish between boat- and shore-based fishing activity with DAR’s gear categories, we assumed that catch is evenly distributed across each reporting block. 

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