Ecosystem management policy implications based on Tonga main tuna species catch data 2002–2018

From 2002 to 2018, the Tongan Long Line fishery collected and compiled catch data (limited to presence records) for Albacore, Bigeye, Skipjack, and Yellowfin. The Tonga Ministry of Fishery and the South Pacific Community (SPC) Office in New Caledonia provided this data. To ensure adherence to regulations, at least two fisheries offices cross-verified the entire fish catch. The data consists of daily fishing positions (latitude and longitude) and date (day, month, and year), organized in a 1^0 spatial grid. Our study utilized catch per unit effort (CPUE), a standardized metric indicating fishing efficiency and effort, calculated by dividing the weight of the catch in metric tons by the number of hooks deployed per fishing record. To align with the temporal scales of the predictor variables, we aggregated the CPUE data into monthly and annual datasets using Microsoft Excel.

Methods
The catch (presence records only) data for Albacore, Bigeye, Skipjack and Yellowfin were recorded and compiled by the Tongan Long Line fishery from 2002 to 2018 and provided by the Tonga Ministry of Fishery and the South Pacific Community (SPC) Office in New Caledonia. The entire fish catch is checked by a minimum of two fisheries offices to ensure compliance.