From the "Game Updates FAQ - 19/05/09" on RSOF, Quick find code: 15-16-541-58855656:
"I really like the Soul Wars activity bar, will you be implementing something similar to the Fishing Trawler?"
As this is quite a new approach for us, we first wanted to see how successful it was in Soul Wars.
Now, due to feedback, we shall be applying the same method (with a few tweaks) to the Trawler.
In other words, Fishing Trawler is going to have a activity bar just like Soul Wars. That means Jagex is finally doing something about freeloaders. Took 'em long enough!