Illegal, Unregulated and Unreported (IUU) fishing is a complex issue which encompasses different levels of activities involving both foreign and African actors. These activities include: unauthorised fishing in closed areas/seasons, illegal fishing by foreign vessels (distance water fleets, or DWFs), fishing with forged licenses or vessel registrations, unreported and misreported catches, discarding, catching undersized fish, taking fish in excess of quota, using prohibited gear and methods, performing illegal fish transhipments, landing in unauthorised ports, fishing without an observer on board and failing to operate a vessel monitoring system .
The economic impacts of IUU fishing are equally widespread. The most critical is the erosion of the fisheries resources of each sovereign state, thus directly threatening the long-term sustainability of its fisheries and jeopardising the jobs, livelihoods and food security of the country’s inhabitants. But IUU fishing impacts also include, for instance, increased harvest costs for legal operators; market sanctions for products from known locales affected by IUU activity; losses of taxation income for the state; invalidation of scientific fisheries data; lost port fees, port handling income, license fees, and fuel sales; price depression due to oversupply into certain markets; and downstream economic multiplier effects .
Several recent studies have shown discrepancies about how best to estimate the economic impacts of IUU fishing. For instance, a substantial portion of nearshore artisanal and subsistence IUU fishing already produces multiplier effects on the local economy. As a result, country-specific economic studies which do not take into account, or minimize, the IUU component of catches are bound to overestimate the economic benefits from fishing, compared to estimates that encompass IUU catches. An example can be found in the comparison between the Africa-wide ex-vessel value estimates reported by Pauly and Zeller (2015)  of about $ 7.1 billion, and the values assigned as ex-vessel in de Graaf and Garibaldi (2014) , about $ 9.8 billion. This difference is aligned with the general perception of IUU fishing to be in the order of 20%, as in MRAG 2005 . However, recent work points to a much larger problem. The data presented by Pauly and Zeller (2016)  suggest that IUU catch levels are far larger than suggested by earlier studies. They estimate that the continent-wide EEZ IUU catch is a staggering 4.7 million tons. This amount excludes discards and is about 80% of the officially reported tonnage of 5.9 million tons.
Moreover, Pauly and Zeller (2016) also estimate that the unit price per kg of this IUU catch is far larger; 2.2 $/kg ex-vessel, compared to the weighted average price of 1.2 $/kg ex-vessel for reported catches. Their estimate of the value of the IUU catch of $ 10 billion (excluding discards) is therefore about 40% larger than their estimate of the value of the reported catch itself ($ 7.1 billion). Part of a possible answer to how and where such a large IUU catch could occur is the Chinese DWF. These authors estimate that Chinese DWF catches are underreported by a factor of about 10, and that the Chinese DWF operating in the African EEZ catches 3.1 million tons, of which 2.8 million tons are IUU. These estimates present a challenge at many levels in dealing with IUU fishing. Of the five African regions, West Africa is hardest hit by IUU fishing, followed by Northern Africa and then Central Africa. 
If all IUU catch could enter the African value chain and stimulate economic activity, then this would add between $ 30 billion and $ 45 billion to the GDP of coastal states in Africa. This is an increase in the coastal African states GDP of between 1.1% and 1.7%. The reliability of this figure must be tempered by the fact that a percentage of this amount is already flowing through the domestic economies, and another portion is caught by foreign vessels whose legal activity is often based on resources that African states do not have the capacity to exploit optimally. Even so, it is clear from Pauly and Zeller’s work that IUU fishing is extremely harming to the economies of coastal African states, and that the previous estimates about the extent of IUU fishing in Africa were probably too conservative, thus failing to adequately reflect the extent of the problem .
IUU fishing impacts go well beyond the strictly economic sphere. There’s a wide array of socioeconomic impacts as well. Besides the already mentioned impacts on food security and nutrition, loss of existing jobs and potential employment opportunities, and impacts on local livelihoods, there are also deleterious effects at the level of safety and security, impacts on women and gender relations, as well as human rights abuses (including slavery) on board IUU vessels. The main social impacts are experienced by local communities that are dependent on coastal resources for food and livelihoods. For many medium- to low-income countries along the coast of Africa there are few alternatives to fishing and fishery-related activities. Thus ensuring the sustainable use and conservation of these marine systems, and enabling safe access to marine waters by coastal communities is of paramount importance. This is especially critical in countries on the eastern and western seaboard of the continent with a low development index and with a large percentage of their populations living in poverty .
Furthermore, there is also yet another aspect of IUU fishing: its impact upon the marine ecosystems. The environmental impacts of IUU fishing are multifaceted and can be classified into three areas: (a) stock status impacts, (b) habitat degradation, and (c) impact on ecosystem services and biodiversity. Some of the most productive and biodiverse marine habitats in Africa that are negatively impacted by IUU fishing are coral reefs. These are often accessible to the high human population density on the coast and are exploited by a range of destructive methods. Thus, the ecosystem service value of the coral reefs of Africa is being degraded and compromised. Other habitats severely impacted by IUU fishing are seagrass meadows and seamounts, which are being destroyed by industrial benthic trawling . This fishing method is worth highlighting not just because of its destructiveness to benthic habitats, but also because it produces a huge amount of discards as a result of its low selectivity. For instance, industrial bottom trawl fisheries for tropical shrimp have extremely high discard rates, in the order of 70% or larger.
By last, the analysis of factors which make Africa particularly vulnerable to IUU fishing highlights the quality of governance as a significant factor. The dimensions of “Control of Corruption”, “Government Effectiveness”, “Rule of Law” and “Regulatory Quality” from the World Bank’s governance index are all negatively related to the percentage of IUU fishing on a country by country basis (using Pauly and Zeller’s estimates of IUU). A further factor in Africa is the legacy of civil wars, social turmoil and other crises which has created fertile ground for IUU fishing to prosper. Other vulnerability factors that emerge are: weak and ineffective MCS, institutional corruption, inappropriate penalties for infractions in comparison to the value of the IUU catch, the availability of flags and ports of convenience, inadequate legal and justice systems, lack of political will to fight IUU, weak port inspections, absence of necessary diplomatic action to facilitate regional cooperation, inadequate data for MCS and inadequate regional sharing of such data, the absence of policies and legislation grounded in sustainability and precautionary principles, and lack of transparency and data sharing around foreign fishing arrangements .
It is therefore clear that taking urgent action to effectively deter IUU fishing in African countries is of the utmost importance, in order to safeguard the long-term sustainability of African fisheries upon which the livelihood and food security of coastal communities depend. One of the tools for creating awareness is to document the negative impacts of IUU Fishing as well as the best practices of monitoring, control and surveillance (MCS). The evidence obtained from such a work on IUU Fishing in Africa can then be used for advocacy work to galvanize African governments to take decisive action against this harmful practice.
 AU-IBAR. 2016. Economic, Social and Environmental impact of Illegal, Unreported and Unregulated Fishing in Africa. AU-IBAR Reports. 219 pp.
 Pauly, D., and D. Zeller, editors. 2015. Sea Around Us Concepts, Design and Data. www.seaaroundus.org.
 de Graaf, G., and L. Garibaldi. 2014. The value of African fisheries. FAO Fisheries and Aquaculture Circular. Rome, Italy.
 MRAG. 2005. IUU Fishing on the high seas: Impacts on ecosystems and future science needs. London, UK.
 Pauly, D., and D. Zeller. 2016. Catch reconstructions reveal that global marine fisheries catches are higher than reported and declining. Nature Communications 7:9.