Marine mammal guidelines for mooring design

[buoy]

Can someone point me to a standard for mooring design that ensures that marine mammals do not become entangled? I am thinking specifically of a bridle or other "closed loop" in a mooring system, and want to know what loop diameter would be large enough that marine mammals cannot become entangled when passing through the loop. I am not certain that there is an official guideline, but if there is I would like to know about it.