Here in Steveston plenty of commercial boats that harvest on the WCVI, etc sell their catches on the dock.
How long of a trip is it to get out to Barclay Sound? By boat it has to be, what, 100+ miles? That is going to take a loaded down seiner (as was the case in this point) a very long time, even assuming they could go full speed which they likely couldn't. What are we talking, 6, 7, 10 hours? Unless their entire hold is iced, that seems like quite a long time to wait, especially considering the first set of fish sat on the boat for most of the opening as well.
I could see them keeping out what they think they can sell on the dock, whatever that is. The entire boat load? No.
Also my guess would be if there is an opening on the WCVI, the commercial buyers in Steveston are not even open.
My guess is boats travel down the day before for an opening. If it is going to be a multi-day opening, they stay there. If not, then they offload a majority of their catch at a buyer in the area and only bring home what they expect to sell on the dock.
Granted, my experience is in the states but I know the seiners there would take the hour or two trip in to Blaine or Point Roberts to offload their catch if they were planning on travelling down to Bellingham and that isn't near as far as WCVI to Steveston.