In medieval times, seafood was less prestigious than other animal meats, and often seen as merely an alternative to meat on fast days. Still, seafood was the mainstay of many coastal populations. Kippers made from herring caught in the North Sea could be found in markets as far away as Constantinople. While large quantities of fish were eaten fresh, a large proportion was salted, dried, and, to a lesser extent, smoked. Stockfish, cod that was split down the middle, fixed to a pole and dried, was very common, though preparation could be time-consuming, and meant beating the dried fish with a mallet before soaking it in water. A wide range of mollusks including oysters, mussels and scallops were eaten by coastal and river-dwelling populations, and freshwater crayfish were seen as a desirable alternative to meat during fish days. Compared to meat, fish was much more expensive for inland populations, especially in Central Europe, and therefore not an option for most.