Depending on the number of lines you intend to pull...you'll find the colored line will help show you where you need to cast after reeling in a fish. You'll need to "see" the other lines so you can make a decent cast between those lines to get your jig back out. Also, the colored line helps you bring in a fish without allowing it to tangle other lines because you can "see" which side the fish is pulling towards. All I have ever used for longlining is 6 lb test.
The fish dont mind that yellow line either.Thumbs Up