An Assessment of the potential for mapping fishing zones off the Coast of Ghana using ocean forecast data and vessel movement

Abstract

This research assessed the feasibility of mapping potential fishing grounds off the coast of Ghana using vessel trajectories and speeds as proxies for identifying migration patterns and fishing behaviour of inshore trawling vessels. The methods involved the extraction of data from Satellite Automatic Identification System comprising position and speed of the vessel from exactEarth Shipview. Daily oceanographic parameters i.e. sea surface temperature, sea surface height, sea surface salinity, and the current velocity between August 2015- January 2016 were obtained from Copernicus (www.marine.copernius.eu). Speed ranges and trajectories indicate that, the vessels steamed between 6.9 to 7.5 knots and fish aggregation mostly occurred closer to the shore predicated on favourable environmental ocean conditions. It was observed that the vessel depicted steaming behaviour in this study, characteristic of a recreational vessel with high speed, moving in straight paths rather than a trawling vessel whose movement occurs in slower and erratic trajectory patterns. The findings strongly suggest that the fishermen operating this trawl vessel have good knowledge of productive fishing grounds. The months with highest probability of catch aggregation were from October 2015 to December 2015, within the geographical locations of longitude -4o 2 ʹ E and latitude 3.5o 6 ʹ N. The highest probability of catch aggregation was observed in October 2015, probably due to upwelling that occurred during that month. It is concluded that, fishing efficiency of inshore trawling vessels in Ghana could be enhanced with maps indicative of probability of fish aggregation in the ocean.