First things first you should always consider your safety when packing to go kayaking and this means taking essential survival equipment with you. This is probably most important if you are going sea fishing because the weather can turn in a second and leave you hopeless against the elements; taking the correct kayak accessories with you may be the difference between a tiring slog home and not making it home at all.
A PFD is the most important of kayak accessories.
You should always wear a PFD without exception. A PFD is a Personal Floating Device and you can buy very comfortable ones now that even have storage pockets, so there is absolutely no excuse whatsoever to leave it lying around the bottom of your boat or, worse still, lying around in your garage.
A map and compass. Don