One of Petri's hideouts was among the fishermen in a village near Catalca called Kalikratia (today's Mimarsinan) after his murder number 12.
The village of Mimarsinan is part of Buyukcekmece County of Istanbul. Travellers used to cross this area by using rafts pulled by ropes hence the names of the lakes called Buyukcekmece and Kucukcekmece. (cekmece meaning pull). Near the Sinan designed bridge there is place called Dalyani. Famous traveler Evliya Celebi does not mention any fishing activity but mentions yilan (eel) and pisi (Flounder/ Platichtys flesus) and this is where Petri must have found some work.
(1) DALYAN (FISH WEIR OR FISH TRAP) the fisherman may periodically check to see how many fish have been caught, in order to determine if it is time to harvest the catch. Traditionally, the fisherman would employ a "feeler" who drops a weighted wire into the weir and -- by observing how the fish bump into the wire--determines the volume of fish contained in the weir.