Illegal Fishing, Your Number's Up!

Aug 15, 2013


Unlike merchant vessels, automobiles, and even cellphones, fishing vessels are not required to have unique identifying numbers that stay with them from construction to scrapping. Although fishing vessels have names, call signs (the codes used during radio transmissions to identify themselves), and other identifiers, they are not permanent and can be changed by owners quickly and easily.

The lack of mandatory, unique identifying numbers makes it hard for authorities to distinguish specific vessels engaged in illegal fishing or to track misconduct to gather evidence of these activities. As a result, vessel owners can circumvent control measures and avoid being traced if they are blacklisted. They can operate for years without leaving a definitive paper trail of their activities, their operating condition, or their compliance status.

Such evasion enables illegal fishers to exceed or ignore catch quotas; fish without licences or with forged documents; use unapproved, destructive fishing gear; and otherwise flout rules intended to make fishing sustainable and environmentally sound.

A solution: mandatory, unique, and permanent ship numbers in accordance with the standards of the International Maritime Organization, or IMO. The value of these numbers extends beyond protection of the world’s fisheries and could provide a vital tool in improving safety and security at sea. Reports from United Nations bodies such as the Office on Drugs and Crime and the International Labour Organization lay out the implications of illegal activities at sea. Serious crimes such as tax evasion, drug smuggling, rights abuses, and human trafficking often involve the use of fishing vessels. Mandatory and permanent identification numbers would help authorities track fishers who try to conceal these shadowy operations.

The Pew Charitable Trusts is committed to a global effort to end illegal, unreported, and unregulated, or IUU, fishing. Crucial to that mission is transforming illegal fishing from a low-risk, high-reward endeavor into a high-risk, low-reward activity through improvements in the monitoring, control, and surveillance of fishing and the enforcement of fisheries laws and policies.

Mandatory use of IMO numbers would help solve problems with current vessel records, at the national level and on the high seas (both within regional fisheries management organizations, or RFMOs, and in those areas where there are no RFMOs). Research conducted by Pew found numerous inaccuracies and inconsistencies in fishing vessel data in the records of ships authorized to fish in RFMO management areas. For example, in an examination of records of authorized vessels from a single RFMO, Pew found:

  • Numerous instances of the same vessel listed under different reporting flags with different specifications on tonnage and length.
  • Vessels listed twice under different names and flags.
  • Multiple vessels listed with the same radio call sign.
  • Vessels that had sunk still listed as authorized to fish.

In addition, some vessels are recorded in more than one RMFO list, but with alternative names and identifying features.

The IMO ship numbering scheme

IMO numbers have successfully served for decades as unique identifiers for merchant ships. Originally designed and maintained by Lloyd’s Register, the scheme was adopted by the IMO in 1987 for merchant ships and is currently administered on behalf of the IMO by IHS Fairplay. Vessels engaged solely in fishing, however, are exempt from the numbering scheme, although owners may request the nine-digit IMO numbers. The information initially provided about the ship is continually updated and cross-checked by IHS Fairplay against multiple data sources.

The IMO ship numbering scheme is widely recognized by users and stakeholders as the best available global identification system. The scheme’s records can provide an independent audit trail of data on each vessel and its ownership.

Why having an IMO number helps

Research published in the journal Science in 2011 cited the lack of IMO numbers for fishing vessels as a prime factor in the failure of port officials to identify and act against illegal operators. That study looked at vessels that had been identified as being involved in IUU fishing activity by one or more RFMOs.

Requiring IMO numbers for fishing vessels would help improve the monitoring, control, surveillance, and enforcement of fishing operations in numerous ways. It would:

  • Allow flag states to more consistently and accurately manage vessels under their authority.
  • Give national authorities information to help them police their waters more effectively.
  • Bring clarity, consistency, and accuracy to RFMO vessel records to provide a better understanding of vessels authorized to fish in their waters.
  • Help port authorities ensure that they are accepting only legally caught fish.
  • Help fish and seafood retailers ensure that the fish they sell is caught legally.

Because of the sheer number of fishing vessels of all sizes, a positive first step would be to require mandatory IMO numbers for larger vessels, which are variously defined by RFMOs as greater than 20 meters in length.

Once IMO numbers are mandatory for fishing vessels, they could help to bring transparency and develop best practices in related areas. For example, seafood processors and retailers could refuse to buy or sell fish that were landed on vessels without IMO numbers. Banks and insurance companies could set policies for financing and insuring only vessels that have the numbers.

The International Maritime Organization is itself considering the use of IMO numbers to enhance three areas of the global governance of fishing vessels: vessel safety, operations, and crew conditions. Once adopted, these initiatives will further solidify IMO ship numbering as the system of record for ensuring that these ships are held to the same standards of operation as the merchant fleet.

International support is increasing for the IMO numbering system

International bodies that support the IMO number system for fishing vessels include the U.N. Food and Agriculture Organization; the Kobe meetings of the tuna RFMOs; and the Workshops on the Consolidated List of Authorized Vessels, or CLAV, of Tuna RFMOs. In 2011, the Commission for the Conservation of Antarctic Marine Living Resources, or CCAMLR, required that all vessels authorized to fish for toothfish in the Southern Ocean have IMO numbers. In June 2013, the Maritime Safety Committee of the IMO recommended that the organization remove the exemption for fishing vessels from its Resolution A600(15), which describes the number scheme and states what types of vessels may join.

Pew advocates a worldwide system of mandatory IMO numbers for fishing vessels and recommends the following actions:


  • The IMO General Assembly should adopt the recommendation of its Maritime Safety Committee and remove the exemption for fishing vessels.
  • Each RFMO should require that all vessels authorized to fish in its waters are required to have IMO numbers.
  • Coastal states should mandate that foreign-flagged ships have IMO numbers before they are permitted to fish in their waters.
  • States should promptly ratify the 2012 Cape Town Agreement, which establishes international rules on fishing vessel safety.
  • Port states should require that all foreign fishing vessels that come in to port have IMO numbers.
  • Banks financing the purchase or repair of larger fishing vessels should make sure that financing is conditional upon the vessels having IMO numbers.
  • Insurance companies that cover larger fishing vessels should make the issuance of policies conditional upon the vessels having IMO numbers, and the insurance coverage should be void for any vessels that are successfully prosecuted for illegal fishing.

For more information, please visit

To view the complete fact sheet, including citations, download the PDF below.

Fact Sheet File: Illegal Fishing, Your Number's Up! (PDF)  

More Work in Environment

(All Fields are required)