I'd check your area's Fish & Wildlife Service or Game Commission/Parks & Rec about the firearm laws or carry requirements.
I'd add that these sites are great gun law resources;
www.knifelawsonline.com www.gunlawguide.com www.mylegalheat.com www.nra.org www.handgunlaw.us .
As for a marine grade sidearm or carry pistol, Id buy a used, good quality Beretta M9, 92F, 92FS, 96/96D Brigader then get it treated with Robar NP3+, Bearcoat, Metalife SS C, Black-T or maybe CeraKote. You can get the spare magazines treated too with a price break,
.
www.bearcoat.com www.robarguns.com www.black-t.com
A Glock compact or duty size pistol(17, 22, 34, 35, 21, etc) could be smart pick.
I'd add a after market Glock plug with a lanyard loop. They can fit in the small gap in the Glock grip.
A Beretta 92/96 with a pistol leash or a Glock with a plug can do fine for canoes or small boats.
I'd also suggest the nylon Bianchi UM92II holster for either semi auto pistol.
This holster is based on the Bianchi milspec M12 rig(for the M9 9mmNATO).
You can tote your Glock or used 92F/96F regular carry, shoulder holster, tanker-chest, SAS/drop leg, cross-draw).
ClydeFrog
www.uscav.com www.blackhawk.com www.natchezss.com www.gunsamerica.com www.jgsales.com www.midwayusa.com www.brownells.com www.policehq.com www.glockstore.com www.glockbooks.com www.galls.com