Chinese fishing companies are engaged in systematic pillaging of west African fisheries on a huge scale, according to a new report from Greenpeace, which also accuses the companies of taking advantage of weak and chaotic governance resulting from last year’s Ebola outbreak in the region.

A two-year investigation by the environmental group found that four Chinese fishing companies, including state-owned China National Fisheries Corporation, carried out persistent “illegal, unreported and unregulated fishing activities and gross tonnage fraud” in west Africa.

In just the latest cases, the Greenpeace ship MY Esperanza documented 16 illegal fishing activities by 12 Chinese vessels in Guinea’s exclusive economic zone in October and November last year, while the Ebola outbreak was raging and countries in the region were unable to monitor their waters.