In order to most efficiently get Pollack, you want to use Mackerel as bait. After your longlines are baited with Mackerel, change your map to show Pollack hotspots and find one with yellow or green in the center. I found that creating an "*" or "X" pattern across the hotspot will get you a pretty decent haul of mostly Pollack.
Remember to try and haul when the buoy map marker has a blue outline, which is about 18 or 19 hours after the second buoy on the longline drops.
Dont worry if you notice the hotspot disappear as you start hauling your lines, all of your lines will still have a decent haul. I used the Follabuen boat with 8 2000 hook lines, until the quota is full. Increasing your quota's are a waste of money, just buy a different boat and continue. I only have 3 boats, the Borge, Sharky and Follabuen, and that is more than enough for most 100 ton achievements.