Should I Track Global Fishing Activity with VMS or AIS?

Posted by Nicole Schill on Aug 4, 2015 2:12:53 PM


The battle of the fishing boat monitoring acronyms rears its head yet again. Here at exactEarth we're asked often about how AIS compares to VMS and why to use one system over the other. We believe that although the systems are different, they can be quite complementary.

As the global illegal fishing crisis intensifies, it's important to look for the best tracking and monitoring system possible.


First it's good to understand a little bit about both of these systems.


Vessel Monitoring Systems (VMS) are used in commercial fishing to allow environmental and fisheries regulatory organizations to track and monitor the activities of participating fishing vessels and delivers position information in near real time

VMS offers a satellite based communication system that offers bi-directional guaranteed communications where every signal is transmitted and received, but at a cost. The costs per signal are shared between the user or fisherman and the authorities wishing to monitor them.

VERDICT: The upside to VMS is that every bit transmitted/received is guaranteed to be delivered but the costs associated prevent it from being a truly practical global solution


AIS is primarily intended as a situational awareness tool and as means to exchange pertinent navigation information in near real-time, via ship-to-ship or ashore. The SOLAS Convention from the IMO requires most vessels over 300 GT or 65’ to have AIS, as well as most commercial tugs and certain passenger vessels domestically.

AIS is used by ships and by vessel traffic services for identifying and locating vessels by electronically exchanging data with other nearby ships, AIS base stations and satellites.

VERDICT: A broadcast system where units are transmitting at all times to each other and to terrestrial AIS networks without a cost per message. AIS is a more economical solution in terms of deployment but with no guarantee of message reception.


Extending the Range

AIS signal transmission is limited to approximately 50 nautical miles and this range limitation can prevent maritime authorities from getting a complete picture of maritime traffic outside of their borders and on a bigger scale.

Satellite AIS (S-AIS) greatly extends the range of traditional AIS as signals are sent and received from many kilometers above land and sea, so the barrier of the horizon doesn’t limit these signals.

An increased need exists to get the complete picture of what’s happening in authorities’ territorial waters, including areas that are distant and isolated from ports and shorelines. S-AIS provides true global tracking of the world’s fishing vessels no matter their location.

The Best of Both Worlds

Where the real advantage lies for maritime authorities is in the correlation of the data from both AIS and VMS. VMS can be used to corroborate AIS data and as VMS outages are common, AIS can be used for additional monitoring such as building a snapshot of the fishing vessel track in open, global waters before reaching VMS range with the use of S-AIS. 

By correlating both data sources, authorities are able to collect as much unique data as possible to identify specific vessel activity. This is particularly useful when building a historical track of a ship to identify patterns and subsequently detect abnormal behaviour. 

Although AIS and VMS are different tracking systems that each have their own advantages, information from both is truly the most effective method for creating a common operating picture for Maritime Domain Awareness.

The introduction of Satellite AIS is a game changer for tracking fishing boats anywhere in the world with no line of sight limitations.

What about tracking all those small fishing boats?

AIS is a Very High Frequency (VHF) technology primarily optimised and designed for high intensity terrestrial-based tracking with reliable range typically limited to approximately 50 nautical miles.  High powered Class A type transceivers are able to be tracked globally by the existing exactEarth AIS satellite network, however due to a variety of complex reasons, transmissions from standard Class B and Identifier type devices that are commonly found on smaller fishing boats cannot currently be reliably tracked from space.

The reception of Class B units from space has been traditionally hindered because Class B units are designed to transmit less frequently at a lower power level.  As Class A populations increase within a satellite footprint, the Class B transmissions become indistinguishable from the general noise floor. In order to improve the detection of low powered devices from space, exactEarth put our patented Satellite AIS detection methods to work with quality AIS designs from our partners at SRT to develop ABSEA. Now reliable terrestrial and satellite tracking of these small vessels is available without requiring expensive equipment and per bit message charges for the ship owner.

When ABSEA is embedded within standard low-powered AIS transceivers, it enables their transmissions to be consistently received by exactEarth satellites. This allows for wide-area tracking of these smaller vessels like the millions currently being used in fishing operations. 

Now any boat, regardless of size, can be equipped with the proper tools for efficient long range tracking and monitoring.

Several decades of overfishing in most of the world's major fisheries has created large de-clines in many commercially important fish populations across the world. The United Nation’s Fisheries and Agricultural Organization (UN FAO) report that 53 percent of the world’s marine fishery resources are fully fished, or fished to the maximum sustainable level.

Today, Illegal, unreported and unregulated (IUU) fishing is recognized as a major threat to achieving sustainable fisheries. Maritime authorities can have a clearer understanding of the fishing activities in their waters now more than ever with enhanced small vessel tracking as well as correlated data from both AIS and VMS.

Click here to learn more about how S-AIS can play a role in sustaining our world's fisheries.


Or to get our S-AIS vessel monitoring application into your operations, fill out a quote today

Click for exactEarth  ShipView Quote

Topics: Satellite AIS, AIS, Satellite AIS data, Vessel Monitoring, Illegal Fishing, Satellite AIS Vessel Tracking, Satellite AIS Tracking, AIS Vessel Tracking,, VMS, tracking fishing boats, Vessel Monitoring System

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