Fishing boats and some other parameters can be customized in the AI/Perta/config.js file
sample code
this.Economy = {
"popPhase2": 80, // How many units we want before aging to phase2.
"workPhase3": 160, // How many workers we want before aging to phase3.
"workPhase4": 300, // How many workers we want before aging to phase4 or higher.
"popForDock": 25,
"targetNumWorkers": 800, // dummy, will be changed later
"targetNumTraders": 40, // Target number of traders
"targetNumFishers": 30, // Target number of fishers per sea
"supportRatio": 0.35, // fraction of support workers among the workforce
"provisionFields": 4
};