i just caught a blue set of plans (not in any trunk or lockbox) for mithril shield spike.  I was fishing next to Nat Pagle trying to get my fishing up to 225.  Then my friend showed up in Theramore, so i was about to leave in midcast, but decided to stay and caught those plans.  Since I'm a blacksmith, i used them.  My fishing was at 217/218  and i was using a 100+ bonus lure as well.  I had been fishing for probably about a total of 25-30 minutes total until i got them.