It is rather common practice in the really industrial fleets (longline, pelagic gill net, trawl) to be secretive about where they fish. I know researchers who try to use high seas fishing data and it is hard because the narrowest may be a 5 degree by 5 degree box of lat-long. At that scale, there is some logic to not sharing the exact where.

At the other end of the scale, and probably the most accurate in WA, is reef net data as each netter fishes one site.