Balloons on fish?

[salt n sage90]

I work above the Everett Marina and there are two green balloons about the size of grapefruit swimming around separately below my window. At first I thought they were just getting pushed around by the wind, but the more I look the more I think they are attached to fish.
We commonly see coho and pinks getting hammered by the seals in here but this is a first. Wonder if its some sort of study.

Just a PSA

[elkaholic123]

I knew a guy years ago who would attach a balloon to a dogfish with a hook and leader through the dorsal fin! After a day of fishing you might see half a dozen balloons out in the possession area swimming around 

[metlhead]

Do it with crappie. They swim back to the school and you can pick em off.

[Alchase]

I wonder if someone is using them as a bobber or Strike indicator?