Vessel Monitoring Research

The Northeast Passive Acoustic Research Group works with collaborators to examine the use of passive acoustic monitoring to remotely monitor vessel presence in protected, closed, or sensitive marine areas. Vessels produce distinctive underwater acoustic signatures. Changes to these signatures can represent a range of vessel behaviors such as transiting, maneuvering, or fishing. By analyzing passive acoustic recordings, we are able to find patterns in vessel presence. This can help managers more effectively understand the level of vessel activity and vessel behavior within a given area.

Six world maps and vessel traffic on each one, by category: all vessels, cargo, tanker, passenger, fishing, and other vessels. — Density maps showing the average number of vessel transits per square kilometer per month during the first half of 2020 (January–June). Vessel categories: a) all vessels, b) cargo, c) tanker, d) passenger, e) fishing and f) other vessels. Credit: Nature Communications

Vessel traffic is a significant contributor to underwater noise. As marine traffic is increasing in our world’s oceans, so is vessel noise. Vessel noise has become the most pervasive source of human-produced noise in our oceans.

Scientists are concerned about the impact noise pollution has on marine animals. Marine mammals are of particular concern, as many rely on acoustics for navigation, communication, locating food, and other survival skills. Sound travels much further and faster underwater than in air. Vessels emit noise at similar frequencies to many marine mammals and fish. This creates disruption for these species, such as masking important sounds or preventing their ability to communicate.

Spectrogram showing a vessel approaching the hydrophone, illustrating the Doppler Effect. — Spectrogram representing a vessel at its “Closest Point of Approach.” Credit: NOAA’s Passive Acoustic Research Group
Hear what vessels sound like in the ocean.

We Listen to Vessels

Our research group analyzes acoustic data in order to understand patterns in vessel presence and behavior. This information provides managers with a valuable tool for understanding the level of illegal activity within a protected or closed marine area. It can help managers target their efforts, such as on-the-water enforcement activities or aerial surveillance, by focusing on the time periods and locations identified by the data. Passive acoustic monitoring makes it relatively easy to collect information over long time periods in remote areas without being limited by environmental factors such as weather or daylight.

Australian Marine Parks

Map of Australia outlining the Australian Marine Park zones. — Australian Marine Park Zones AMP = Australian Marine Parks; NPZ = National Park Zone Credit: NOAA’s Passive Acoustic Research Group

The Australian Marine Parks project uses passive acoustic monitoring to understand vessel presence and behavior within marine parks.

Australian Marine Parks comprise more than 60 marine protected areas spanning more than 3 million square kilometers. Parks Australia contributes to the protection of biodiversity in these areas and the long-term viability of the marine environment. This includes habitat for endangered and critically endangered species such as blue whales and gray nurse sharks.

Within some Australian marine parks, certain areas are further designated as National Park Zones. This designation prohibits any unauthorized extractive activities, including recreational and commercial fishing. Since 2018, we have been working in collaboration with Parks Australia to deploy and analyze data from acoustic monitoring devices in National Park Zones. Scientists analyze these data for patterns of vessel presence and behavior within numerous Australian marine parks. Park managers and rangers use this information to understand the degree of compliance and to target their efforts to improve compliance within their respective parks.

NOAA's Office of Law Enforcement

Map showing the northern Pacific Ocean and the U.S. Exclusive Economic Zone that lies within this area. — Map of the U.S. Exclusive Economic Zone Credit: NOAA

NOAA’s Office of Law Enforcement is responsible for policing possible violations of our federal marine resource laws throughout U.S. waters. We work with NOAA’s Office of Law Enforcement to evaluate how we can use passive acoustic monitoring to develop innovative ways to evaluate illegal vessel activity in closed or protected areas. We analyze acoustic signatures of vessels engaged in fishing and non fishing activities. We hope to identify when illegal fishing activity is taking place in a closed or protected area.

Hong Kong Marine Protected Areas

Map of Hong Kong, showing marine protected areas. — Marine Protected Areas in Hong Kong waters. Credit: WWF Hong Kong

The geography and geology of Hong Kong’s harbor provide accessible passage to parts of the Eastern world. This makes the Port of Hong Kong one of the busiest seaports in the world for container vessel operation. In addition, the seas of Hong Kong are home to an extensive range of marine life and important habitats. These ecosystems are under threat by human activity, including illegal fishing within protected areas.

Marine Protected Areas are designated regions in which management efforts focus on ocean conservation and marine resource protection. These areas are essential for long-term viability of marine resources, yet in urban areas such as Hong Kong they can experience high levels of vessel traffic. We are collaborating with Southeast Asia Marine Mammal Research Ltd. to deploy passive acoustic recorders in several Marine Protected Areas. We are documenting vessel presence and movements for non-compliance or illegal incursions. SEAMAR is an organization focused on research of threatened marine mammals in Asia.

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Sleuthing with sound: Understanding vessel activity in marine protected areas using passive acoustic monitoring

Last updated by Northeast Fisheries Science Center on 03/21/2022

Acoustics