Growling for food: acoustic emissions during competitive feeding of the streaked gurnard

The streaked gurnard Trigloporus lastoviza produced only one sound type, a growl, lasting up to 3 s and consisting of repeated groups of typically one to three pulses. The foraging fish followed two different strategies. In the first, the fish circled the feeding area, grasped a food item and fled, sometimes displaying aggressively to competitors. With this foraging strategy, fish usually made sounds as they circled, grasped and fled. Fish that growled while circling were more likely to grasp a food item subsequently than were silent fish. The second feeding strategy occurred when a fish had already ingested food or failed to get any. In this case, typically fish searched for food on the substratum or approached and touched other individuals that were feeding, sometimes grabbing food that was spat out during food handling by the other fish. Although payback experiments would be needed to draw firm conclusions on the communicative function of growling during competitive feeding in the streaked gurnard, the results suggest that sound production confers advantages Co individuals competing for limited food resources. (C) 2000 The Fisheries Society of the British Isles.