FWIW, the combine harvester already took all our jobs, changed the food supply chain such that only a small number of people were making any money off of what is now "big farming." 80% of humans were farmers before that machine was around. Now it's closer to 5 - 10% in countries where combine harvesters are available (they cost over $250k, so not accessible to poor farmers).

This talk about the fishing community losing their jobs... I mean... it's harsh in the short term, but in the long term, it's just like all those farming communities that went bust. Times change. The localization of labor changes.
This is at the core of ong's argument, so I'm confused why he'd to point to a short-term harsh adjustment as a negative. If the fishing industry doesn't support the scale at which Grimsby has become accustomed, then Griimsby needs to adjust and re-accustom itself to the changing times. The short-term adjustment as Grimsby moves away from being a fishing community is just the path of human progress.

The mere argument that a community is losing its industry is not necessarily a sign that the industry should be saved.

Maybe it is, maybe it isn't. Context matters.

If the issue is foreign fishers fishing the waters, so that UK fishers can't fish the amount of fish they could fish, which the market supports, then that's in line with ong's argument.
If the foreign fishing issue is a red herring (lol), as the quote from the House of FancyPants that Poopy shared indicates, then Grimsby is understandably upset that their industry is failing, but it's nothing to do with the EU or Brexit... it's just a changing world. Sorry Grimsby, but if you're clawing onto a failing industry that doesn't support the scale at which you've historically had it run, then that's on you to adjust your industry, create or invent new jobs and find prosperity in a new way.