with a default ANG

src/main/java/analysis/AnalyseSpawnerFeatures.java

@@ -59,12 +59,16 @@ public class AnalyseSpawnerFeatures extends AquaNismsGroupProcess<DiadromousFish
 
 	private transient Map<RiverBasin, QueueMemory<Double>> primiparousMemories;
 
+	private transient DiadromousFishGroup defaultGroup;
+
 	protected static transient ObservablesHandler cobservable;
 
 	@Override
 	public void initTransientParameters(Pilot pilot) {
 		super.initTransientParameters(pilot);
 
+		defaultGroup = (DiadromousFishGroup) pilot.getAquaticWorld().getAquaNismsGroupsList().get(0);
+
 		// keep the river basins
 		riverBasins = ((RIOBasinNetwork) pilot.getAquaticWorld().getEnvironment()).getRiverBasins();
 
@@ -222,6 +226,11 @@ public class AnalyseSpawnerFeatures extends AquaNismsGroupProcess<DiadromousFish
 	}
 
 
+	public double getMeanLengthOfMatureFish() {
+		return getMeanLengthOfMatureFish(defaultGroup);
+	}
+
+
 	public double getMeanLengthOfMatureFish(DiadromousFishGroup group) {
 		double sumOfLength = 0.;
 		double numberOfMatureFish = 0.;