The North Pacific/Bering Sea area has the most intense regulatory program out of the (if I remember right) five geographical areas that U.S. fisheries have been divided up into. The way they collect most of their data to regulate with is through observers onboard vessels and at the plants.
The observers go out on the trips and their main priorities are to collect data pertaining to catch (how much per haul/trip, where they're fishing at, target species data such as male/female, length, avg weight.); also record where the boat is fishing in regards to off-limits areas, etc.; any interaction with marine mammals/seabirds; then a whole list of lesser priorities. Basically while the crew is bringing fish onboard the observer is out on deck collecting random samples, for use in extrapolations to total haul weight and sex/length/weight data for the target species. They have no authority to make the crew do anything, that's reserved for NMFS enforcement, just observe and report. So it can put you in tough positions sometimes, for example when a captain suggests you not bother to go out on deck for actual measurements and instead just kick back in the galley and he'll tell you how much they caught. Or when you've found that a crew member has made a fillet of a protected species they aren't allowed to touch.
Crab species, herring, halibut, and salmon are regulated by the state of Alaska, so I didn't work on any of those boats - I worked strictly for the National Marine Fisheries Service (NMFS) on boats fishing for everything else (cod, pollock, flatfish, etc.)
I'm not going to say our job was anywhere near as tough as the fishermen, but an observer who actually does their job correctly puts up with alot of the same tough conditions and grind. I put in my share of 18-20 hour days in sub zero weather.