I have been watching long-lining for sword fish on U-tube. I have been trying to find out the diameter of the running line.
Is the running (the long line the drop lines are hooked to) monofilament or some other type of material? What is the test of this line? Very interesting! All hard work.

My father used to long line sword fish, tuna, marlin in the canyons off the mid Atlantic coast. I’ll ask him tomorrow and try to post a few pictures. He also clammed, and ran a dragger for fish and scallops. This is how he spent the bulk of his career until he remarried and moved inland.

I watched swords life on the line and it was interesting how those lines worked and the cussing when they got crossed with someone else’s line.

A quick text to dad revealed a few answers. The diameter of the main line varied from 3-4 mm. And the “branch lines “ were half that diameter. They were clipped onto the main line and baited mostly with whole squids , and a glow stick for an attractant in the deep water.

3 mm monofilament is 900 lb
4 mm is roughly 1300 lb

Monofilament was used for both the main line and branch lines

Joe:
Thank you for the information. I find it interesting that the glow stick would work. I tried them ice fishing in the winter, and they would not work. Thank your dad for me. Hard way to make a living!

I believe Santiago hauled in a giant Blue Marlin.

Did the mercury scare in the 60's stop your dad from fishing swordfish?

In my quest to catch all nine of the world’s billfish (still need a spearfish), the sword was the most boring - by far - fishing 1800 feet deep with a 14 lb weight. One bite in 20 hours of fishing.

WhiteCliffs
You were not fishing, you were working!! A 14 lb. weight at 1800 ft. If that is not work, I do not know what is.
When fishing salmon on Lake Michigan sometimes we would use lead line 200 ft. from the boat. Sometimes when someone would get a fish on, they would let someone else land the fish.