Overfishing and IUU fishing

In 2015, fish accounted for about 17% of animal protein consumed by the global population and provided about 3.2 billion people with almost 20% of their average per capita intake (FAO, 2018). People in developing countries have a larger share of fish protein in their diets, with the highest per capita fish consumption found in small island developing states (SIDS), particularly in Oceania.

In a world heading towards 10 billion people, seafood is critical to global food security, as a source of both dietary protein and micronutrients needed in aquaculture. But scientists warn that the joint threats of global heating and overfishing are reducing fisheries productivity and threatening stock health.

The 2019 Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES)  report on global biodiversity concludes that fishing has had the greatest impact on marine biodiversity in the past 50 years (IPBES, 2019). The percentage of stocks fished at biologically unsustainable levels increased from 10% in 1974 to 33.1% in 2015 (FAO, 2018). Industrial fishing now covers 55% of the ocean (Kroodsma, 2018), and overfishing is exacerbated by widespread illegal, unreported or unregulated (IUU) fishing.

Together, overfishing and IUU threaten both a global source of food and the entire ocean ecosystem.  


Overfishing is the removal of fish species faster than they can replenish themselves. It is defined by FAO as “stock abundance reduced by fishing to below the level that can produce maximum sustainable yield.”

According to the United Nations’ Food and Agriculture Organisation (FAO), 90%of fish stocks are now either fully fished (59.9%) or overfished at biologically unsustainable levels (33.1%) (FAO, 2018). That is the highest proportion ever recorded. By contrast, the number of underfished stocks have reached the lowest levels ever recorded, rapidly declining over the past decade from 24% to just 7%.

Catches from wild fisheries peaked in 1996 at around 130 million tonnes per year and have been declining by 1 million tonnes per year since then – not because we are choosing to catch fewer fish but because they simply aren’t there. According to FAO, world total marine catch was 81.2 million tonnes in 2015 and 79.3 million tonnes in 2016 (FAO, 2018).

In 2015, the Mediterranean and Black Sea had the highest percentage (62.2%) of unsustainable stocks, closely followed by the Southeast Pacific (61.5%) and Southwest Atlantic (58.8%) (FAO, 2018).

As well as driving negative impacts on biodiversity, overfishing also reduces fish production. Studies have estimated that rebuilding overfished stocks could increase fishery production by 16.5 million tonnes and boost the industry by US$32 billion, which would benefit the food security, economies and wellbeing of coastal communities (Ye et al., 2013).

Bycatch – the capture of sea life while fishing for a different species – is closely tied to overfishing. It is a serious marine threat that causes the needless loss of billions of fish, along with 300,000 whales and dolphins (WWF, n.d.-a) and tens of thousands of albatross (McVeigh, 2019), and is the biggest threat to endangered sea turtles (WWF, n.d.-b).

Waste is another big problem. Catching and processing fish generates a significant amount of waste from both discards at sea and in on-shore processing (Archer et al., 2001). According to FAO, recently there has been a slight decrease in losses between landing and consumption, but they still account for about 27% of landed fish (FAO, 2018).

Reasons for overfishing include: harmful subsidies (e.g. tax relief on fuel); poor fisheries science; poor decision-making mechanisms; lack of precautionary management; lack of transparency; absence of high seas governance; and IUU fishing.


Overfishing is driving serious species depletion.

About 80% of all the top predatory fish have gone from coastal areas of the North Pacific and North Atlantic (Tremblay-Boyer et al., 2011).  In the last 30 years, European eels have experienced up to 99% decline in some regions (Correia et al., 2018); Pacific bluefin tuna has declined by over 97% (Nickson, 2016); and Atlantic bigeye tuna populations are approaching collapse (Galland, 2018).

Salmon have disappeared from many rivers on both sides of the Atlantic, and global populations of wild Atlantic salmon have dropped from 8-10 million fish in the 1970s to 3-4 million today (Atlantic Salmon Trust, n.d.).

An estimated 100 million sharks are killed every year (Worm et al., 2012) and the IPBES report highlights that almost a third of shark species are threatened. Alarming recent findings by IUCN’s Shark Specialist Group classified 17 of the 58 shark species it evaluated as facing extinction (Hood, 2019).


IUU fishing is an international threat that massively undermines efforts to sustainably manage fisheries. It is estimated to produce seafood worth up to $23.5 billioneach year worldwide, the equivalent of up to 20% of all wild marine fish (Agnew et al., 2009). The IPBES report puts the IUU share of the global catch as up to 33%.

IUU robs poorer countries of rich natural resources, jobs and nutrition. It threatens food security, has links with international crime and puts further pressure on already endangered species.

Briefing prepared on behalf of the OneOcean initiative www.oceanprotect.org contact info@oceanprotect.org

Back to Resources