If it's a matter of life and death, such as offshore fishing, you probably want a real commercial service.

Like Garmin (Iridium based texts back and forth) or Zoleo. These are physical units that may offer texts or just a simple "sos" button.

Prohibitively expensive, and also not available to 90% of the planet's commercial fishermen.

For them, an iPhone can be an entire year's profit.

The people in TFA aren't going to be featured on The Deadliest Crab.