Sad reality of life at sea. I'd say all these observersers should be given Sat phones for their own personal safety. It is reckless to send them out on the high seas with hostile foreign crews without a life line.
Good thing I'm not in Donald Trumps shoes because I'd order some good old fashioned American gun boat diplomacy retaliation. Any American observer that went missing on the high seas, so would the boat that was responsible for the observers death. Submarine loses a torpedo, one less pirate fishing vessel. Pretty soon the observers would be feeling a lot safer doing their job and regulations might be taken more seriously. Extreme yes, but what justice will these murdered men ever see for simply performing their jobs of trying to protect the world's endangered fisheries. When the pirate fishing vessels have stripped the last of the remaining oceans bounty, and people are left with no seafood people will moan that someone should have done something sooner. Only it will be too late by then.