In a broad sense, Mankind has always found a way to wet a line, so in that regard, fishing from a kayak is the same as fishing from any watercraft. However, the challenges associated with a particular craft, is what adds a touch of adventure to this sacred outdoor ritual.
From an historical perspective, kayaks have been used for fishing for several millennia. By the time the Russian fur hunters overran the western coastal areas of Alaska, courageous kayakers were running down and slewing whales with poison-tipped harpoons and arrows. Now there's a 'catch of the day'!
Russian Orthodox priests recorded much of what is known about Native history in the mid to late 18th Century Alaska. Their notes and drawings show kayakers fishing for the huge, barn door flatfish halibut - from kayaks lashed in tandem side by side. Once a huge fish was hooked and hauled to the surface, it was clubbed and probably tied alongside the kayak.
Fishing is possible from any kayak although narrower, sleeker boats and most surf skis are just too nimble for any serious attempts. The sit-on types have flaunted their use as stable fishing platforms since they were first introduced a few decades ago. Today, some come with fishing contraptions installed from bow to stern. These and the wider, more stable "recreational" kayaks actually tout fishing as one of their main uses clearly marketing to this popular activity. For those who fish from sit-on's, and to a lesser degree, the wider, big-cockpit designed rec' boats, fishing is similar to that undertaken from a canoe or small skiff. It's when you fish from a conventional sea kayak that the game gets a little more exciting.
The paddler's inherent ability to steady the kayak throughout the various activities associated with fishing underlies the entire process. You have to feel at one with your kayak as you cast, retrieve, release or keep fish usually with both hands busily attending to fishing instead of paddling.
Sitting right in the water, elbows only inches above the surface, requires a few minor adjustments to any casting prowess one has achieved on land. Even fly fisherpersons have adapted ways to accent their casts from a kayak. One big hazard that kayakers face is hooking the lure or fly onto the back deck or rudder. It is nearly impossible to remove a barbed hook from the tightly woven deck lines used on most kayaks today. It's either get an assist from a fellow paddler or head back to shore (the third option is to break the line and get a new lure!)
That brings up the issue of fishing rod length. Some suggest a short rod that is basically an extension of hand jigging (a form preferred by many). While the short rod keeps all the action within a few short feet of the cockpit, it is way too short if a larger catch decides to run - as is often the case with most game fish. Unless your rod tip can be swung completely around the kayak, beyond bow and stern, a fish cutting right angle escape routes under your cockpit will take your rod with it. Swinging a complete circle around your kayak assures you of being able to keep control of your catch no matter where it runs. I know some kayakers who are so good at 360 degree rod handling that they can even make pin-point casts backwards, over their head.
In some fisheries, creating complex lures from components is part of the overall experience. On the trail of ocean-run king salmon, for example, a savvy angler knows that a combination of divers, skirts and other components are sometimes needed to fashion just the right lure for ideal depth runs and current speed. It's usually a matter of bringing an assortment of tackle on board and creating that killer lure on the spot. It goes the same for kayakers, too, with a few minor restrictions.