Gaff  The gaff is one of your most useful tools when landing larger fish. Though rarely used, you shouldn't go fishing without at least bringing one along.  Using the gaff can sometimes be a judgment call.  You're not going to gaff a fish you intend on releasing. You sure don't need to gaff a 4lb bass either (overkill).  And you only want to gaff a fish  if you're absolutely sure the size of the fish falls within the guidelines of your local fish regulations.  With some practice you can learn to become quite effective at landing fish this way.  TipWhen you're ready to land a fish, lower the gaff into the water at a depth less than the fish (below the fish) .  With your other hand holding your rod, guide the fish over the gaff "trap" you've set.  When the fish gets over the gaff, pull the gaff straight up (vertically), sending the gaff hook  into the fish.  When possible, try gaffing the head and neck region (easier said than done).

Fish Stringer (aka-divers stringer, game clip) Without a doubt, this tool can save your fish from swimming back into the abyss more than any other.  Some fishermen like to use it just like the divers do, stringing their catch one by one on it.  When fishing from a kayak,  it's more useful tool to use as a landing aid.  Gaff your fish (keep the fish below the waterline), open your stringer up and run it up the gills and through the mouth, or down the mouth and out the gills.  Secure the stringer and the fish by latching it shut.  If you notice from the photo, the stringer has a clip on it.  That clip fits into a retractor that I fasten to one of the back straps in my tank well. As soon as the stringer is strung through the fish and closed, it is secure.  You can then extract the gaff hook from the fish and determine if the fish needs to be subdued by further action (see below).

Club (a.k.a. bat or billy) The club is only pulled out for certain situations.  Some game fish can range in between 20 to 80 pounds (excluding sharks), and even higher depending upon your local fishery.  Obviously bringing a large game fish on your kayak still flopping could create a serious dilemma, possibly  resulting in injury to the kayak angler.  Subduing the fish with the club can be your best option.  In ideal conditions, the fish would first be gaffed, the fish stringer attached, and then struck with the club as many times  necessary.  The  stringer can be gripped to maintain a secure hold on the fish.  Striking the fish with a club can be a very tricky process since maintaining balance from the kayak can become more difficult due to the shifting and jerking motion you experience from this action. Clubbing the fish on the head is usually the best target.  Though certain fish may respond better when struck in the belly.