Illegal, unreported and unregulated (IUU) fishing is at the centre of a crisis of sustainability. Nowhere is that crisis more visible than in western Africa. Current rates of extraction are driving several species towards extinction while jeopardising the livelihoods of local fishing communities across Senegal, Ghana, Sierra Leone, Liberia and Mauritania.

Drawing on a unique satellite tracking database from FishSpektrum, this report by ODI and porCausa presents new evidence of the scale and pattern of IUU fishing. It focuses on 'reefers' - large-scale commercial vessels receiving and freezing fish at sea - and the use of containers. It provides evidence of practices that undermine multilateral governance rules aimed at curtailing IUU fishing and promoting sustainable, legal practices.

The report identifies pathways for countries in sub-Saharan Africa to move towards greater transparency and sustainable management of fisheries to prevent the irreversible depletion and possible extinction of species, and to preserve the marine ecosystems where the fishing activities take place.

Transferring fish between ships at sea makes it harder to tell which fish are caught legally and which are not.

This map developed by CartoDB tracks the movement of 35 reefers through western African waters in 2013. A high density of hotspots and an erratic track pattern highlight areas where transhipment (moving catches from small fishing boats to reefers) may be occurring.

Greater investment in regional patrols to detect and deter illegal fishing would allow western Africa's governments to follow up suspicious manoeuvres identified through 'hot spot' activity.

The report calls on western Africa's governments to follow the lead of Senegal and Cote d'Ivoire and ban transshipment in their waters. We recommend that ships caught engaging in IUU fishing should be blacklisted and prohibited from entering waters in the region.