More than 5,000 people died or went missing in the entire Mediterranean sea in 2016 [IOM, 2017], mostly along the route from North Africa to Italy. The vessels carrying migrants and refugees are often small inflatable boats, which are sometimes filled up to ten times their capacity. Wooden boats of different sizes, and ranging from fewer than twenty people on board to over seven hundred, also make the sea journey, although their use is recorded to have declined since anti-smuggling operations in the Central Mediterranean started destroying them after rescue operations to prevent their re-use. Vessels are usually supplied with insufficient fuel for the journey to Lampedusa or Sicily: they merely have enough to reach international waters. Once this runs out, migrants and refugees are simply left drifting on the waves hoping for rescue.

In some cases, vessels are equipped with a Thuraya satellite phone, and the number of the Rome-based Maritime Rescue Coordination Centre (MRCC). This enables those on board to request a rescue once they reach international waters. The MRCC records the position the vessel, and shares its approximate GPS coordinates with other vessels in the area that can assist, often in the form of a public broadcast warning.

Broadcast warnings are produced by the World-Wide Navigational Warnings Service (WWNWS). They are used to warn ships of potential safety risks in a region. They contain a wide range of information, including alerts on vessels adrift at sea, cable laying operations, and debris in the water. They also notify ships of nearby emergencies, invoking a responsibility to respond, according to the 1974 International Convention for the Safety of Life at Sea (SOLAS). The convention states: “The master of a ship at sea, on receiving a signal from any source that a ship… is in distress, is bound to proceed with all speed to the assistance of the persons in distress…” [UN Treaty Collection, 1974]. The 1979 International Convention on Maritime Search and Rescue further requires that “assistance [is] provided to any person in distress at sea… regardless of the nationality or status of such a person or the circumstances in which that person is found” and that effort is made to “provide for their initial medical or other needs, and deliver them to a place of safety” [IMO, UNHCR, and ICS, 2015].

A diverse set of actors conduct rescues in the Central Mediterranean. From October 2013 to October 2014, the majority of rescue operations fell to the Italy’s Operation Mare Nostrum, which assisted over 130,000 migrants [Taylor, 2015]. More recently, the EU-led Operations Triton (which addresses border control) and Sophia (which tackles smuggling) have coordinated international assets in the region. NGOs have also played a far larger role in rescues, with the help of vessels deployed by organizations such as MOAS, SOS Mediterranee, MSF, Save the Children, and ProActiva Open Arms. These ships are equipped to transmit Automatic Identification System (AIS) data, thereby sharing their movements with other vessels and maritime authorities.

AIS is a maritime communications system through which passenger ships, cargo ships over 500 tons, and international ships over 300 tons regularly broadcast both static data, including their identifiers, their vessel type, and the flag under which they sail, and dynamic data, including their latitude and longitude, speed, course over ground, and destination [All about AIS].

3 October, 2016.

After almost two months on standby, the Bourbon Argos, a merchant vessel hired by Médecins Sans Frontières (MSF), was called back to the waters of North Libya. It encountered eight stranded vessels, and managed to take on board a total of 1,019 people [MSF, 2016-1]. MSF staff treated the patients on board for a variety of minor illnesses.

“In the absence of safe and legal alternatives to dangerous boat journeys, people continue to die by the hundreds in the Mediterranean Sea […] Although search and rescue operations continue to be an insufficient answer to this tragedy, today shows just how needed humanitarian and independent organisations like our own are in the Central Mediterranean. But let’s be clear, search and rescue is not enough. People urgently need safe and legal routes to reach Europe; it’s the only way to stop deaths at sea.” Tommaso Fabbri, MSF’s Head of Mission in Italy [MSF, 2016-1]

In only six months, MSF operated vessels (including the Bourbon Argos) have conducted more that one hundred different rescue operations, saving the lives of 14,547 people. MSF continues to stress that although search and rescue is lifesaving and essential, the only way to truly stop deaths at sea is to provide safe and legal alternatives to dangerous sea crossings.

“With the number of deaths continuing to dramatically increase and the deteriorating situation in Libya, we continue to consider the European focus on deterrence and security dangerously myopic and completely inadequate to respond to this crisis.” Stefano Argenziano, MSF's Operations Coordinator [MSF, 2016-2].

The Bourbon Argos’ intense journey was just one of many. In 2016, the MRCC recorded 1,424 search and rescue operations, recovering a total of 178,415 people. Most were assisted by NGOs (26%), followed by the Italian Navy (20%), and the Italian Coast Guard (20%). However, a substantial portion of migrants (almost 8%) continue to be recovered by merchant vessels, which are generally ill-equipped for such operations [MRCC, 2016].

To better understand how these different actors contribute to the rescue effort, the digital records of their vessels’ movements can be broken down into rescue and non-rescue patterns. The resulting rescue signatures provide concise summaries of the vessel's behaviour in specific rescue sequences. These can help profile rescue activities, and create data models of rescue operations.

A systematic analysis of rescue signatures can yield insights into exactly how many rescues vessels are conducting, where and how they happen, and how long they take. This could prove useful for coordinating the humanitarian response to the Mediterranean migrant and refugee crisis. As seen with the Bourbon Argos, rescue signatures can show how multiple migrant boats may be discovered in sequence by a single rescue vessel, forcing it to work continuously to bring people on board until it reaches full capacity. They can also reveal how multiple vessels coordinate to conduct a single rescue.

Rescue signatures might further highlight gaps in NGO-led rescue operations that may lead to vessels sinking undetected. This could help better target operations. The signatures could also help ensure that rescue vessels are successfully coordinating their presence in a given region. Further, they could reveal how much impromptu rescues are costing the commercial shipping industry, as well as how shipping routes have changed in response to the evolving situation. Finally, they might demonstrate how migration activity changes according to weather trends and sea currents.