Troling for Salmon but catch ling cod.

I have noticed that many seem to catch lings trolling for salmon. My question is in the water column, are you on the bottom and the by catch is a ling. or can it be quite away from the bottom. I hope to get some Ideas before the next salmon season. Most likely I'll have to get a guide. And I think I know one to ask. 

There's been a few times over the years where my friends and I were spearing fish way up in the water column like at 20-25ft when the bottom was down at 60-65. 

Occasionally lings would come in like a guided missle and grab a wounded fish on the end of our pole spears.  Once it worked perfectly the wounded fish had gotten off the spear and was doing it's death spiral when the ling grabbed it.  A pole spear can be cocked back in the blink of an eye, so that ling ended up on the dinner table.

I'm not sure if it's sight or sensing vibrations like trolled baits but lings can zero in on food from quite a distance.

And, reading some of Eric's reports over the years he mentions losing rigs from hitting the bottom, so I guess sometimes it's just being down near the bottom.

Lings will come all the way to the top if they're after something.  When fishing for them, I've watched them chase my swimbait right to the boat and grab it.  When I was salmon fishing this year I caught 3 or 4 lings, but I did have a lot of line out.  The salmon were near the bottom.  The thing about kayak fishing for salmon is that you don't keep up a constant speed, so your set-up sinks towards the bottom when you stop paddling for for a little while.

A few times this year we were catching lings while trolling in 80-100 ft of water and down riggers were only down 40 ft.  Happened more often when we caught a small rock fish and the ling would latch on and hitchhike up to the surface.

Catching lingcod and other "bottom fish" is definitely possible while trolling shallow.  Late this season I've been slow trolling near the bottom, but the early to mid season trolling is much higher up, and we catch lots of lings and blacks especially.  Even caught a usually-on-the-bottom vermillion while trolling at 20 pulls in July near the Bell at the Cove in 60' of water.  Also hooked and fought a big Pacific Halibut while trolling well off the bottom at the Cove...