Recreational boat traffic effects on fish assemblages: First evidence of detrimental consequences at regulated mooring zones in sensitive marine areas detected by passive acoustics

We assess the impact of recreational boat traffic on sensitive habitats in the Western Mediterranean using passive acoustics. We compared underwater sounds in three regulated mooring locations vs a pristine location; and temporal differences in the pristine location vs the nearest mooring between high and low touristic seasons. We measured the number of pulses/minute, fish pulse patterns, and percentage of boat noise occurrence and its relative average power level. At the pristine location, the call rates and their complexity were significantly higher and the motorboat noise was significantly lower. The temporal trend of biophonic sounds decreased significantly in the pristine location. In contrast, in the mooring sites, the motorboat noise decreased significantly and the fish calls remained at low levels in both seasons. In conclusion, motorboat noise negatively affects the complexity of the fish assemblages but could be conditioned to their historic uses.