Am I missing something . . .
. . . or will it be fairly easy to build waterborne chaff to confuse the detectors?
Spam the shark, as it were.
The US Navy's plan to detect mines and other underwater objects by their electrical fields - in the same way as sharks and rays find prey - has moved closer to reality. Elasmobranch fish (rays, sharks and suchlike critters) have various senses, including relatively conventional vision and smell. But they also have slime-filled …
Sharks stay away from the electric lines because they indicate danger/headaches to them, which are neither here nor there for the shark-in-a-box --- it is controlled by humans or programmed to ignore such strong and recognizable signals.
The presence of chaff-like stuff would indicate something's up, or indeed make the sharks go on a wild-goose chase and waste time. Here again, roboticists can develop chaff-recognition tech or soft where sharks are just stumped.
I'd be pretty optimistic something useful comes out of it, if only a sole-vacuum to precision-fish large but not pregnant flat fish. I'm in favour of research with edible by-products; memory research should be done preferentially on lobsters etc (given the continual need for `naive', unused, individuals).