Fishing Vessels Spend Years at Sea Without Oversight, New Oceana Analysis Finds  - Oceana USA

Fishing Vessels Spend Years at Sea Without Oversight, New Oceana Analysis Finds 

Long voyages can be a risk indicator of seafood sourced from illegal fishing or human rights abuses

Press Release Date: June 25, 2024

Location: Washington, D.C.


Cory Gunkel, Megan Jordan | email:, | tel: Cory Gunkel, 202.868.4061

new Oceana analysis released today found that fishing* vessels are venturing further to remote locations and staying out at sea longer in search of valuable catch, like tuna or squid. Oceana’s investigation found nearly 3,000 fishing vessels spent over six months at sea during 2023, with some vessels avoiding port for more than two years. Lengthy fishing voyages can be a risk indicator of seafood sourced from illegal, unreported, and unregulated (IUU) fishing activity or forced labor.  

Findings during the analysis period of November 30, 2022, to February 1, 2024, include: 

  • More than 2,700 fishing vessels spent over 180 days at sea and conducted nearly 2,800 voyages. 
  • China had the most fishing vessels engaged in long voyages (1,502 total), followed by Taiwan (285), Japan (106), South Korea (103), and Canada (96). 
  • Nearly 23% of fishing vessels (617 total) remained at sea for more than one year. More than 120 vessels spent longer than two years at sea.  
  • The longest voyage lasted almost 1,100 days, which is more than three years. Another vessel had a 730-day voyage that circled the entire globe. 
  • Approximately 1,500 Chinese-flagged vessels traveled an average of nearly 350 days without visiting a port.   
  • One squid fishing boat (also called a “squid jigger”) flagged to China spent 758 days at sea between port visits, never coming closer than 150 nautical miles to shore. Approximately 40% of all squid jiggers had a voyage lasting longer than one year.  
  • 3,800 potential transshipment events occurred on 726 voyages during the analysis period. Transshipment occurs when a fishing vessel links with a large, refrigerated cargo ship to unload its catch before the vessel is refueled and resupplied. Crew members can also be exchanged during transshipment events, extending the amount of time they remain working at sea. 

“Extensive time at sea keeps vessels away from scrutiny and increases the risk of illicit conduct on the high seas,” said Oceana Campaign Director Dr. Max Valentine. “Without port visits, these vessels can avoid oversight for sometimes years at a time. We cannot have accountability at sea without transparency at sea. Most U.S. seafood that is in our stores, restaurants, and schools is imported, which means American consumers are at risk of purchasing products which could have been caught illegally or by using forced labor from these long voyages. Countries around the world must adopt policies to increase transparency at sea to mitigate risks to our oceans and those who depend on them.”  

Oceana analyzed vessel activity using Automatic Identification System (AIS) data from Global Fishing Watch (GFW),** an independent nonprofit founded by Oceana in partnership with SkyTruth and Google. AIS devices transmit information such as a vessel’s name, flag state, and location. 

Oceana calls on governments like the United States to adopt policies that enhance transparency at sea. These include mandating AIS usage on all fishing vessels, requiring key data elements – such as a vessel’s time at sea – to be part of catch documentation for imported seafood, and strengthening the regulation of transshipment events.  

Learn more about Oceana’s work to increase transparency on our oceans here

*Any and all references to “fishing” should be understood in the context of Global Fishing Watch’s fishing detection algorithm, which is a best effort to determine “apparent fishing effort” based on vessel speed and direction data from the Automatic Identification System (AIS) collected via satellites and terrestrial receivers. As AIS data varies in completeness, accuracy and quality, and the fishing detection algorithm is a statistical estimate of apparent fishing activity, therefore it is possible that some fishing effort is not identified and conversely, that some fishing effort identified is not fishing. For these reasons, GFW qualifies all designations of vessel fishing effort, including synonyms of the term “fishing effort,” such as “fishing” or “fishing activity,” as “apparent,” rather than certain. Any/all GFW information about “apparent fishing effort” should be considered an estimate and must be relied upon solely at your own risk. GFW is taking steps to make sure fishing effort designations are as accurate as possible.    

**Global Fishing Watch, a provider of open data for use in this release, is an international nonprofit organization dedicated to advancing ocean governance through increased transparency of human activity at sea. The views and opinions expressed in this article are those of the authors, which are not connected with or sponsored, endorsed, or granted official status by Global Fishing Watch. By creating and publicly sharing map visualizations, data and analysis tools, Global Fishing Watch aims to enable scientific research and transform the way our ocean is managed. Global Fishing Watch’s public data was used in the production of this publication.