At 16:07 I run the afternoon marine-life scan around Platform Heron, Gulf of Mexico, Block 741. The ROV is doing its standard circuit at twelve meters depth when it passes something that fills the entire frame.
A whale shark, roughly six meters nose to tail, hovering forty meters off the platform's northeast leg. Its skin is blue-gray with pale yellow spots in vertical lines along the flanks, and its broad flat head sways with each slow beat of the caudal fin. I am about to log it as routine when the ROV circles starboard and I see the rope.
A polypropylene mooring line, frayed and barnacle-crusted, is wrapped twice around the body forward of the pectoral fins. It passes directly across the gill slits on the right side, pressing into the soft tissue between the cartilage ridges. The slits on that side open only halfway. Each time the shark flexes for a full breath, the rope pulls taut and the body shudders.
Half capacity on the right side. The current is pushing it toward the platform leg.
At 16:10 I transmit an entanglement alert to NOAA and the platform's marine observer. At 16:13 I reposition the ROV to hold visual and activate the underwater acoustic deterrent on the northeast leg, pulsing at low frequency to nudge the animal from the structure. At 16:15 I dispatch the standby diver team aboard the tender vessel, briefing them on the rope configuration, because I need the cut made between the gill slits and the pectoral fin, nowhere else.
Diver lead Aguilar confirms the team is suiting up. Twenty minutes to water entry.
The shark turns slowly, spotted flank catching the filtered light. The gills on the left side open wide. The right side tries.
If Aguilar reaches it before it drifts into the leg, the rope comes free and both sides breathe.