Apparent reduction of illegal trawler fishing effort in Ghana's Inshore Exclusive Zone 2012-2018 as revealed by publicly available AIS data

摘要

Automatic Information System (AIS) derived information on sampled trawler fishing effort (hours fished) within Ghana's Exclusive Economic Zone (EEZ) was analysed for the period 2012-2018. Publicly available data were obtained from Global Fishing Watch (GFW) for the period 2012-2016 and for 2017 and 2018 (until 30 June) through a license granted to the author by GFW. Trawler intrusions in the Inshore Exclusion Zone (IEZ), which is reserved for small semi-industrial vessels, canoes and recreational fishing vessels, were extracted and hours fished per month and year calculated. Sampled trawler fishing effort within the IEZ as a percentage of total sampled trawling fishing effort within the EEZ decreased fourfold from 15.6% in 2012 to 3.8% in 2015. From 2015 to 2018 it remained stable at 4-5%. Concurrently a fourfold increase in sampled trawler fishing effort was apparent in patches of less than 30 m depth on the continental shelf. There is ambiguity, however, if these patches are covered by the Fisheries Act 625 (2002) of Ghana. Trawler intrusions were highest during the main (July-October) and minor (January-February) upwelling periods. Activities of the Fisheries Enforcement Unit unlikely reduced trawler intrusions into the IEZ, as this process was already ongoing for two years preceding its inauguration. However, the abrupt shift away from trawler fishing activity in the Central Region in 2014 might well have been caused by FEU activities. Coastal fishing communities complaining about trawler intrusions in the IEZ can profitably use AIS data to substantiate their claims and push the government for law enforcement and sanctions.