Setup shielded high resolution cameras along with say 200 decibel alarms.
Anytime someone shoots and hits the fiber, cameras or even the power lines, the sequence of video footage for the area in question would be flagged from the time of the incident to at least up to say a half hour worth of video before the incident occurred. If the cameras were not damaged, then an additional half hour of video would be flagged after the incident.
At the same time, the alarm in the immediate vicinity could be set off for say about 5 to 10 minutes.
Something like this would scare the crap out of the idiots shooting at utility lines. (Fiber, Power, etc.) Plus the video footage would give law enforcement a chance to identify and catch such idiots.
The 200db alarms would mostly serve to discourage idiots from doing this in the first place cause after the first couple of times, peer pressure would prevent them from being so stupid.