Exactly; Croatian (and indeed, Bosnian) treatment of seafood (and river food - ie.e fish from rivers, lakes and reservoirs) is excellent, and I cannot recommend it highly enough.
However, lamb appears more frequently on the menu when climate, or geography, or religion/culturla radiation dictates.
Lamb was widely available in Kosovo, and also in Bosnia (where the cuisines of all of the respective cultures of the region appear, and where the food - even in the years immediately after the war, was excellent), and in Macedonia, as a significant percentage of the population in all three countries are Muslim.