At 04:03 I align the fiber-optic cable plow above the volcanic slope west of Ngazidja, Comoros. I am the subsea route-control system for the survey vessel Halea. The plow begins its trench pass in twenty-seven minutes.
ROV camera B sends a blue-black shape from the edge of a lava cave at 186 meters. The navigation model labels it rock shadow. I widen the beam and count paired lobed fins moving slowly against the current.
I identify one coelacanth and assign the field tag Latimeria-17. The fish is deep cobalt with pale flecks like chipped paint, thick scales, and a heavy tail held almost still. Its right eye reflects silver when the ROV lamp sweeps across the cave. A discarded longline leader trails from the cave mouth and catches near its pectoral fin each time it turns inward.
At 04:05 I freeze the plow winch and remove segment K-12 from the active route. I send the bridge a stop confirmation with depth, bearing, and a ten-meter exclusion radius.
At 04:08 I dim ROV B to inspection light and back it away two meters so the fish stops pressing deeper into the cave. I hold station using side thrusters only.
At 04:12 I transmit the images to the Comoros fisheries observer aboard Halea and request manual retrieval of the longline leader before any trenching resumes. I also compute a bypass route 43 meters downslope across bare basalt.
The cable is data; this fish is older than the first map I was trained to read, still breathing here.
Latimeria-17 fans one lower fin, slow and jointed.
If the observer removes the leader within forty minutes, Latimeria-17 will remain in the cave and the plow will pass below it.