  The sea crossing from Libya to Italy is one of the world's most dangerous and
politically contentious migration routes, and yet over half a million people
have attempted the crossing since 2014. Leveraging data on aggregate migration
flows and individual migration incidents, we estimate how migrants and
smugglers have reacted to changes in border enforcement, namely the rise in
interceptions by the Libyan Coast Guard starting in 2017 and the corresponding
decrease in the probability of rescue at sea. We find support for a deterrence
effect in which attempted crossings along the Central Mediterranean route
declined, and a diversion effect in which some migrants substituted to the
Western Mediterranean route. At the same time, smugglers adapted their tactics.
Using a strategic model of the smuggler's choice of boat size, we estimate how
smugglers trade off between the short-run payoffs to launching overcrowded
boats and the long-run costs of making less successful crossing attempts under
different levels of enforcement. Taken together, these analyses shed light on
how the integration of incident- and flow-level datasets can inform ongoing
migration policy debates and identify potential consequences of changing
enforcement regimes.
