Detecting Illegal Fishing Vessels

Illegal Fishing Detection expedition


Illegal, unreported and unregulated (IUU) fishing is an international problem that threatens the health of marine ecosystems globally. Marine Protected Areas (MPAs) create safe havens for fish stocks and wildlife, and provide strong socio-economic benefits for coastal communities around the world.

In 2010, the UK Government established a new MPA to halt commercial fishing across 640,000km2 of the Indian Ocean called the British Indian Ocean Territory (BIOT), which is 370 miles south of the Maldives and is home to the some of the most biodiverse waters on the planet. However pressure from illegal fishing still threatens the wildlife and fish stocks that reside there. 


Technical Solution

Since 2010, ZSL has worked closely with the BIOT administration (BIOTA) in the Foreign and Commonwealth Office and with the Bertarelli Foundation to develop an ambitious programme of research to support better management of the marine reserve.

In 2017, ZSL collaborated with the BIOTA to trial underwater acoustic sensors to detect illegal fishing vessels within the British Indian Ocean Territory. This formed part of a wider initiative to trial emerging technologies to boost enforcement efforts across the whole MPA.

ZSL, together with JASCO Applied Sciences, evaluated and tested readily available underwater acoustic sensors (or hydrophones) to be integrated with ZSL’s Instant Detect satellite communication solution; a real-time early warning system for protected areas

The solution uses hydrophones to listen around the clock in remote archipelagos and coral lagoons. JASCO’s intelligent algorithms are able to distinguish engine tones from large ships to even the smallest wooden vessels and ZSL’s Instant Detect system then transmits a real-time alert to a control room.

Because it is able to detect smaller vessels, the solution can complement large scale satellite technologies which are typically designed to monitor larger vessels, and by ensuring the technology is compatible with open analytics tools such as OceanMind, enforcement teams are able to have a suite of enforcement tools to enable them to better monitor MPAs and reduce illegal fishing.

An expedition took place to test underwater detection equipment



Whilst underwater acoustics are widely used to monitor ocean health and human impacts, their application to monitor illegal fishing vessels is fairly innovative. ZSL led a collaborative process with enforcement and technology specialists to ensure the solution was fit for purpose and cost effective. In 2017, ZSL and JASCO Applied Sciences attended the April 2017 expedition to BIOT to thoroughly test and validate the technology. Results:

  • Tested under water acoustic sensors and algorithms within coral lagoons.
  • Extensive modelling to validate the technology will provide BIOTA with ~90% coverage at two fishing hotspots, spanning a total of 500km2.  
  • Captured long term underwater noise recordings to understand noise patterns within a reef environment. 
  • In addition to listening to vessel detection events, the hydrophones can be used to study the presence and behavior of marine mammals by listening to their whistles and clicks. 
  • Completed the concept design for an autonomous vessel detection system that fulfills the needs of Marine Protected Area managers, specifically:
    - High and accurate detection rate 
    - Improves efficiency of patrol teams
    - Able to withstand harsh environments 
    - Can be left in situ for up to three months 
    - Can be moved to different hotspots within the MPA
    - Affordable and low ongoing costs


What’s Next?

ZSL seeks new funding to extend our research to new protected areas, trial the technology at different sites and share learnings. We have the blue print and partnerships in place to build a prototype system and we wish to continue our research and development to investigate new emerging sensors that can help detect illegal fishing vessels. If you have a trial site, relevant experience or new sensor you would like to speak to us about please contact 

Project Information

People Involved

  • Sophie Maxwell, Conservation Technology Lead
  • Emily Loving, Project Manager
  • Tom Letessier, IOZ Chagos Consortium Science Coordinator
  • Rachel Jones, Project Manager 

General enquiry: 

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