I have to ask as a UK citizen living in BC , why do you feel you need to carry firearms on board,
Reasonable question. Speaking only for ourselves we do not carry a firearm in the plane or on the boat or in our vehicle on backcountry trips for protection against other humans. But because of where we live and the remoteness and ruggedness of some of the places we visit by air, water, or road, we carry a firearm for two reasons.
One, and this is particularly true wth the plane, is for bear protection. Not so much in the boat although if one dinghys ashore in remote areas, either to explore, beach comb, fly fish, or give the dog some excercise, an encounter with a bear is a very real possibility. And we have encountered plenty of them over the years in BC and SE Alaska.
Two, and more important, it is a part of our survival equipment. Again, much more of an issue with the plane than with the boat or vehicle.
In our case a shotgun fills the bill most effectively. Carrying a handgun for bear protection, besides being illegal in Canada, is an excercise in futility because a charging bear is so hopped up on adrenaline that a shot that would normally kill it may well have no effect at all, at least not until it reaches you and takes you apart. The one way a handgun is effective against a bear is if you can jam it between his jaws as he bites down on you.
So we do what we were advised many years ago by the Alaska Fish & Game folks and carry the shotgun pictured earlier in this thread which at very close range has tremendous stopping power when loaded with the right kind of shells. I know this from experience, unfortunately.
On the survival side, loaded with a much lighter shell, the shotgun is an effective way to gather small game--- squirrels and such--- in case you are so far out in the bush or out of contact that rescue will be awhile in coming.
And a shotgun is legal to possess in the two countries we frequent.
The two photos below were taken by my wife a few weeks ago when we were fishing up the north end of Vancouver Island. She did not use a big telephoto lens, by the way. In the lower shot the bear was about fifteen feet from her. Up there, bears are all over the place. These are black bears and as such are not so much a potential problem although a mother and cubs can be. Brown bears are a somewhat different story.