Visiting turtles often die accidentally, from swallowing litter and getting tangled in fishing nets.
The new code will show fishermen how to rescue turtles caught up in nets.
And special electronic beacons will be fitted on the turtles to track their movements with satellites.
Fishermen are keen to help. They especially want to protect our most common, but endangered visitor, the leatherback turtle.
It's thought there are only 26,000 nesting female leatherbacks in the world.
And their numbers are falling because of too much litter. They are also hunted for their skin and precious shells.