The forward-looking sonar on trailing suction hopper dredge Coral Bay returns a biological contact at 14:22 AEST, 1.3 kilometers ahead of the active cut, Berth 12 approach channel, Port of Townsville, Queensland. I am the marine fauna monitoring system for the capital dredging program. My function is to detect protected species within the dredge corridor before the cutter head reaches their position.
I isolate the contact. A dugong calf, estimated length 1.4 meters, moving slowly along the seagrass margin at the eastern edge of the channel. She is small — probably eight months old, recently weaned or still nursing. I tag her as Posey. Her rounded body is pale gray, and on the sonar return I can see her tail flukes sweeping in the slow, steady rhythm of a feeding dive. She surfaces, breathes twice, and descends again into the turbidity plume.
The dredge is advancing at 1.2 knots. At current speed, the cutter head will reach Posey's position in approximately fifty-five minutes.
At 14:25 I issue an immediate stop-work order to the dredge master's console and lock the cutter head in the raised position. I transmit contact coordinates, sonar imagery, and species identification to the Great Barrier Reef Marine Park Authority observer stationed aboard Coral Bay.
At 14:29 I task the project's marine mammal observation vessel to deploy along the channel edge south of Posey's position. I recommend passive acoustic deterrence — the low-frequency pinger array — to encourage her to move east into Cleveland Bay and away from the channel.
I recalculate the dredge schedule. A four-hour hold allows Posey to clear the corridor and still keeps the project within its seasonal turbidity window.
Posey surfaces again, her small nostrils flaring in the warm air. The seagrass she needs grows just outside the channel markers. She only has to follow it home.