The bodies of 13 migrants from sub-Saharan Africa were found washed up on Tunisia’s Mediterranean coast this week as authorities struggle to stem unauthorized boat crossings from North Africa to Europe.

Tunisia’s Coast Guard said the bodies were recovered on Wednesday near Mahdia, a coastal Tunisian town about 142 kilometers (88 miles) from the Italian island of Lampedusa, which is closer to North Africa than the Italian mainland.

Tunisia, along with neighboring Libya, have long been the key launching pads for Europe, and thousands of migrants reach Lampedusa in ramshackle boats every year, including many whose journeys are facilitated by smugglers.

According to local court spokesperson Ferid Ben Jha, the bodies were all of men from sub-Saharan Africa and an investigation is underway to determine where they came from.

Tens of thousands of people from as far away as Bangladesh attempt to make the dangerous journey across the Mediterranean Sea every year to reach the shores of Spain, Italy, Malta and Greece. Many are fleeing poverty, war, climate change or persecution.

Earlier in September, five bodies were recovered near Monastir, Tunisia, including that of a woman and a child.

Recently, Tunisia has ramped up efforts to patrol its territorial waters with European funding and help, leading to a drop in migrant crossings and deaths.

Tunisia’s National Guard said in June that from January through May, authorities recovered bodies of 462 migrants and intercepted more than 30,000 migrants off Tunisia’s coast, compared to the same period last year, when 714 bodies were recovered and nearly 22,000 migrants were intercepted.

Roughly 10,000 migrants arrived in Italy by boats from Tunisia in the first half of this year, less than a third of the total that arrived in the same period in 2023, according to Italian authorities.

“The decrease in the Central Mediterranean is largely due to preventive measures taken by the Tunisian, Libyan and Turkish authorities,” FRONTEX, the European Union’s border and coast guard agency said in a statement earlier this month.

The trend is consistent throughout the majority of routes to European Union countries, where unauthorized migration has dropped significantly this year. However, as border and maritime security has been tightened in the Mediterranean, there has been a spike in migrant arrivals to the Canary Islands, a Spanish archipelago close to the Africa’s Atlantic coast that is increasingly used as an alternate stepping stone to continental Europe.

The United Nations refugee agency estimates that at least 1,000 people die or go missing each year at sea.

A nongovernmental organization, the Tunisian Forum for Economic and Social Rights, said it counted more than 1,300 dead or missing off Tunisia in 2023.

As the number of migrants who reach Europe drops, the number stuck in transit along the Tunisian coastline has risen.

Thousands hoping to get on a boat to Europe, live in encampments on the outskirts of Tunisian cities and towns, where tensions have soared between migrants from sub-Saharan Africa, Tunisians and security forces.