I've spent a month or two of many summers kayak camping in Haida Gwaii, and relying mostly on fish for food. I've trolled and mooched up lots of spring, coho and pink salmon. Many were caught while we were in transit between camping spots 20-30 miles apart, or just while paddling to explore. I've never used a downrigger or flashers from a kayak, and never would, although I downrigger-troll with my power boat 6 months a year. Use the right tool for the job!
If you're going to fish with downriggers, cannonballs, and sounders, use a power boat and do it right. The advantage of the kayak is the ability to work shallow, in close to the kelp where the feed is and the feeders are. Instead of electronics, use your eyes. An eagle making a dive could be going for herring, or fish feeding on herring. Diving birds like auklets give you an idea how deep the feed is. They dive at about 3 feet per second, so if one goes down for 20 seconds and comes back up with bait in his beak, you can be sure the bait is no deeper than 30 feet. Seagulls working bait are another obvious sign.
I also don't see any need for a rod holder. Our technique is to have a heavy shock cord across the deck directly in front of the cockpit. We use a medium-action 7' rod with a spinning reel loaded with 10-lb. test line, with the rod tip pointed astern, the drag quite loose, and the handle of the spinning reel pointing up, and held in place by the shock cord. When a fish strikes, the shock cord gives, then recoils, setting the hook, and the fish runs freely against the loose drag until you ship your paddle, pick up the rod, and play the salmon as normal. It's the low-cost, low-tech way to go.
Lures depend on species. For pink salmon, nothing beats a 1/2 ounce nickel-plated Blue Fox Pixie spoon with the Flo Red insert. No other color pattern or size compares. It works best with a swivel, and late in the season, coho also like it. Troll it with no additional weight, and don't go too fast, because pinks are lazy. They also like a pink shrimp-pattern weighted streamer fished slowly near the surface.
For coho and springs, a 3.5" Coyote Spoon in a variety of colors, especially Cop Car and GloGreen, is a winner. A rubber core sinker weighing around 1/2 or 3/4 ounce set 5' from the spoon will get the lure down to 10-15 feet at Kayak speeds, and if you're trolling the edges of kelp beds along a drop-off where you should be, that's plenty deep. Unless you're strong enough to sustain high speeds, forget about hoochies and plugs.
Another good kayak method is casting and jigging a Buzz Bomb, with or without a herring strip on the hook. I personally like a Pink Pearl. You don't need a depth sounder, because again you'll be working the edges of kelp beds. If you're lucky, you'll see bait being driven to the surface. Just cast, let it sink, reel in a ways, let it flutter back, and reel again. Don't be in a hurry. Sometimes the Buzz Bomb is most effective if you let it hang below the boat with a piece of herring strip, and jig it gently every minute or so, just enough to produce the fish-attracting vibration.
A kayak is also ideal for mooching with herring, either whole or cut-plugs. In fact, I've caught lots of coho and springs just hanging a weighted hunk of belly strip cut from a rockfish 25-40 feet under the boat. Be sure to have a big-enough landing net or a gaff, and a stringer is also handy for the bleeding.
A kayak is big fun for bottom fish. I've jigged up lots of lingcod up to 62 pounds (which I always release unless they're under about about 15 pounds) from the kayak, and caught several halibut up to 45 pounds ( I've shaken some bigger ones, which is also quite exciting). A hali in a kayak is no joke!!! Carry the right equipment: a good club; a good gaff (no nets!!!); a stinger with a shielded, sharpened snap on the end of the rope; and a large, sharp knife. I use a heavy 6' rod with a star-drag Penn reel loaded with 60lb line. If you use a circle hook for halibut, you usually have the fish hooked solidly, so you can play him out as much as possible before bringing him to the boat.
You're way ahead of the game if you can roll a played-out halibut white-side up without lifting his head out of the water, clamp the rod between your knees, grab him by the tail, and run the smooth side of your gaff down the lateral line. For reasons unknown, this usually leaves halibut temporarily docile. Drive the stringer snap through the jaw, and snap it closed. If the fish is still docile, take the knife, and cut around the tail, then snap your wrist, breaking the spine. If he comes alive at this point, you have him on both the stringer and the line, and most of his power is gone.
Only at that point do I gaff them through the head, because lifting the head earlier reenergises them, and leaves you trying to fly an angry muscular kite on a sharp piece of metal at eye level or above. Take the club, and play your favorite drum solo for awhile on his head, then cut the gills, and let him bleed out. Realize that you don't want to hit him between the eyes, because you'll just be bashing his cheek. I fish from a double kayak, so I lift the bled-out fish into the open front cockpit, which is lined with a slime-resistant garbage bag.
Halibut are notorious for coming back to life like Dracula, so if it's a larger specimen, I take a few feet of 1/4 inch line, with a piece of straightened coat-hanger wire on one end and a loop tied in the other, lasso the tail, run the wire and rope through the gills and out the mouth, bend the fish in an arc, and tie off to the tail-loop. He might still come back to life, but he can't do much.
If you do decide to sit and jig or mooch, DON'T do it right in the middle of a busy trolling tack! The best thing about kayak fishing is working water that's a threat to propellers, being able to see, hear and smell what's going on around you, and having it all to yourself. It's minimalist fishing, but sometimes less is more.
