diff --git a/src/core/configuration/Config.ts b/src/core/configuration/Config.ts
index aac2822b0..96bf6052f 100644
--- a/src/core/configuration/Config.ts
+++ b/src/core/configuration/Config.ts
@@ -160,7 +160,7 @@ export interface Config {
   defaultDonationAmount(sender: Player): number;
   unitInfo(type: UnitType): UnitInfo;
   tradeShipGold(dist: number): Gold;
-  tradeShipSpawnRate(): number;
+  tradeShipSpawnRate(numberOfPorts: number): number;
   defensePostRange(): number;
   defensePostDefenseBonus(): number;
   falloutDefenseModifier(percentOfFallout: number): number;
diff --git a/src/core/configuration/DefaultConfig.ts b/src/core/configuration/DefaultConfig.ts
index 741577742..82b11b8f8 100644
--- a/src/core/configuration/DefaultConfig.ts
+++ b/src/core/configuration/DefaultConfig.ts
@@ -156,7 +156,12 @@ export class DefaultConfig implements Config {
   tradeShipGold(dist: number): Gold {
     return 10000 + 150 * Math.pow(dist, 1.1);
   }
-  tradeShipSpawnRate(): number {
+  tradeShipSpawnRate(numberOfPorts: number): number {
+    if (numberOfPorts <= 3) return 180;
+    if (numberOfPorts <= 5) return 250;
+    if (numberOfPorts <= 8) return 350;
+    if (numberOfPorts <= 10) return 400;
+    if (numberOfPorts <= 12) return 450;
     return 500;
   }
 
diff --git a/src/core/execution/PortExecution.ts b/src/core/execution/PortExecution.ts
index a6f85d89f..5aafe9cee 100644
--- a/src/core/execution/PortExecution.ts
+++ b/src/core/execution/PortExecution.ts
@@ -66,7 +66,10 @@ export class PortExecution implements Execution {
       return;
     }
 
-    if (!this.random.chance(this.mg.config().tradeShipSpawnRate())) {
+    const totalNbOfPorts = this.mg.units(UnitType.Port).length;
+    if (
+      !this.random.chance(this.mg.config().tradeShipSpawnRate(totalNbOfPorts))
+    ) {
       return;
     }