STOP USING nylon line as a wreck reel line, lift bag line or a deco line without recovering it. Divers that use nylon line without recovering it are creating a deadly environmental hazard.
I have been diving North Atlantic shipwrecks regularly since 1972. In the past five years I have witnessed two incidents where turtles have been tangled in nylon line and expired on the bottom. I know of two other incidents where turtles were cut free from this line and escaped with the help of divers. Besides turtles, I have witnessed numerous fish, crustaceans and even divers become entangled in this line.
This recent surge of problems can be directly attributed to a using permanent nylon line for diver uses. A diver that irresponsibly pays out nylon line and does not recover it is creating an entanglement that will kill for decades. Start navigating using your recognition techniques. Deploying line is a cave diving technique that disables the mental process of learning the wreck. The diver recognizes his line but does not have a clue where he is in relation to the wreck. If you do pay out nylon line make every effort to recover it. Give yourself adequate time to reel the line in. Better yet use biodegradable line (sisal or packing twine) This can be payed out and recovered too, but if it is left on the wreck it will disintegrate in less than six months.
More importantly do not use nylon as a deco line where you have to cut the line on the surface and leave it. The new diver con senses is that this line(sisal) is not strong enough and too bulky too handle. I can only relate my personal experience of using both. Nylon is strong, but cuts and chafes easily. A diver will be more likely to tangle himself up using this line and there is a greater risk that the line will cut on a sharp wreck. 1/4 sisal has more texture and is less likely to tangle, but needs to be changed seasonally to maintain integrity. In reality the upline is used only to maintain the diver or the artifact over the wreck and does not need to have more than a hundred pounds of strength. Sisal more than adequately handles these needs. I have used sisal for numerous decompression dives and for recovering hundreds of artifacts with out losses.
What ever your choice of line is, do recover all nylon line you deploy. Stop killing marine life and be a responsible wreck diver.
Good Wreck Diving!