Illegal fishing - where vessels operate in violation of the laws of a fishery. This includes fishing out of season; harvesting prohibited species; using banned fishing gear; catching more than the set quota; fishing without a licence.

Unreported fishing - fishing that has been unreported or misreported to the relevant national authority or regional fisheries management organisation.

Unregulated fishing - this applies to fishing conducted by vessels without nationality or flying a flag of convenience, or flying the flag of a State not party to the regional organization governing the particular fishing region or species. It also relates to fishing in areas or for fish stocks where there is a lack of detailed knowledge and therefore no conservation or management measures in place.

IUU fishing occurs worldwide, however as developed countries improve monitoring and decrease quotas, pirate fishing fleets are increasingly targeting developing nations that cannot afford to patrol their own waters and enforce fisheries laws.

Faced with dwindling fish stocks some governments have now woken up to the seriousness of the situation and put in place a range of management and conservation measures. Yet as the global demand for fish and seafood continues to grow, an incentive exists for fishermen to ignore such handicaps in an attempt to make lucrative short-term gains, albeit at the expense of longer-term environmental, economic and social objectives.

With a single bluefin tuna fish selling for in excess of US$100,000 on the Japanese sashimi market, operators are cashing in on the vast profits to be made.

IUU fishing substantially minimises the operating costs for vessel owners who can avoid paying for licences, onboard observers, vessel monitoring systems or catch documentation systems, and in many areas IUU fleets specifically target commercially valuable species, such as tuna, Patagonian toothfish, shrimp and lobster. However, IUU fishing can also decimate far less lucrative stocks, but ones that nonetheless provide very important food sources and employment opportunities for people in developing countries.

Alongside the obvious economic incentives, IUU activities are facilitated by a number of well-documented shortcomings in national and international controls, including Flags of Convenience; insufficient Monitoring, Control and Surveillance (MCS) in Exclusive Economic Zones (EEZs) and on the high seas; Ports of Convenience, and uncontrolled at-sea transshipment.

a) Flags of Convenience
A flag of convenience ship is one that flies the flag of a country other than the country of ownership - this makes it virtually impossible for unscrupulous ship owners to be caught and punished for illegal fishing. A major portion of IUU fishing could be eliminated if the loophole in international law that allows states to issue Flags of Convenience was closed.

b) Monitoring at sea
IUU fishing can thrive in areas where monitoring, control and surveillance activities (patrol boats, surveillance aircraft, satellite monitoring, onboard observers, etc) are insufficient. For example, in many developing states a lack of available resources, combined with large areas to police and the high costs of enforcement mean that fishing vessels can operate with impunity. Similarly, MCS on the high seas (the waters beyond 200 miles from the coast) is extremely difficult due to the huge areas and costs involved, and is therefore an environment in which IUU fishing can flourish.

c) At-sea transshipment
One of the main ways in which IUU fishing can remain undetected is by vessels trans-shipping their catch at sea. Large vessels remain at sea for months at a time, refueling, re-supplying and rotating their crews. By transferring their catches onto transport ships (reefers) IUU fishing vessels never need enter ports with their illegally caught fish. Moreover, the illegally caught fish is laundered by mixing with legally caught fish onboard transport vessels.

d) Ports of Convenience
All fishing vessels must at some point visit a port to land their catch, refuel and take on provisions, and IUU vessels are no exception. Regulating access to port facilities states can therefore be a highly effective way of controlling IUU fishing. However, certain ports fail to do so and the existence of such "Ports of Convenience" is seen as one of the major reasons that IUU fishing continues to occur. Las Palmas de Gran Canaria is a major Port of Convenience, providing services to IUU fleets operating off the coast of West Africa, and hosting a number of companies that operate IUU vessels. It also serves as a gateway through which illegally caught fish can enter onto the huge EU market: from Las Palmas it can be transported anywhere within the EU with virtually no further inspection as to its origin.

e) Penalties
Even in the unlikely event that a vessel is caught engaging in IUU activities the penalties faced by the crew, captain and vessel owner are often too small to act as an effective disincentive, and are therefore seen simply as a cost of doing business. To take the EU as an example: in 2003 more than 10% of vessels on the EU's fishing register (some 86,585 vessels) were fined for committing serious infringements of fisheries rules. However, EU vessel owners paid only 28.7 million Euros in penalties for breaking the law and over-fishing, fines that represent just 0.004% of the value of fish landed at EU ports in 2002.

Fines imposed on (EU) vessel owners not only need to be drastically increased, however, they are also in urgent need of harmonization. Currently, penalties vary hugely between member states with, for example, illegal fishing in Belgium incurring an average fine of just €375 as opposed to €19,255 in the UK.

IUU fishing is a global phenomenon, occurring in virtually all fisheries from shallow coastal waters to the deep oceans. Accurate data on the scope and scale of IUU fishing is hard to come by as it is in essence a clandestine activity. A recent report commissioned by the UK Department for International Development estimated that the total annual value of IUU fishing worldwide (for the years 2003-2005) is between US$2.4bn and US$9.5bn, thus accounting for a significant proportion of global catches.